Topical tetracycline compositions

[0002] Tetracyclines are broad-spectrum antibiotic, which are routinely used orally for the treatment of dermatological conditions, such as acne and rosacea. However, despite their high therapeutic value, tetracyclines are very unstable, and they are known to be incompatible with many formulation excipients, including water, various protic substances and oxidizing agents.

[0003] Topical tetracycline was the first topical antibiotic approved for the treatment of acne, its use has been limited because of the skin penetration problems of the active ingredient (Adi§en E et al, “Topical tetracycline in the treatment of acne vulgaris”, J Drugs Dermatol. 2008;7:953-5). The vehicle of this product is an ointment base, comprising petrolatum (which is greasy and unusable in the case of facial treatment of acne and rosacea). [0004] Tetracycline hydrophobic compositions intended to be mixed with an external source of protic liquid are known. They comprise a hydrophobic non-hygroscopic silicone thickening agent, preferably a silicone elastomer, in concentrations of more than 5%. This

US1DOCS 7672543vl mixing results in substantial solubilization of the tetracycline, thus rendering it “suitable for topical delivery. Such a product, which requires mixing two components prior to administration by the patient is cumbersome and has no or little practical or viable value; and furthermore, it would degrade and form degradation products if left for a while prior to treatment.

SUMMARY

[0005] The present application relates to oleaginous gel formulations, foamable formulations and foams comprising tetracycline, which are stable and their therapeutic uses. [0006] The application also relates to foamable formulations and foam without surfactants; and or without surfactants and polymeric agents. In one or more embodiments the hydrophobic solvents are provided as part of a drug carrier. For example certain drugs require hydrophobic solvents in order to solubilize them.

[0007] In one or more other embodiments, the hydrophobic solvents are provided to facilitate or enhance the intradermal penetration or delivery of a drug. In one or more additional cases, the hydrophobic solvents are provided to have an occlusive effect at the target site, for example where the site of treatment is a damaged skin and the occlusive effect of hydrophobic solvents is desirable. The present application further relates to compositions comprising hydrophobic solvents and their uses. The application further describes semi solid gel compositions that liquefy on application of mild shear force such as gentle rubbing.

[0008] In one or more embodiments there is provided topical therapeutic hydrophobic breakable composition comprising

a. a carrier comprising

i. about 60% to about 99% by weight of at least one hydrophobic oil ii. at least two viscosity-modifying agents selected from the group consisting of a fatty alcohol, a fatty acid and a wax

b. a tetracycline antibiotic characterized in that (i) at least part of the tetracycline antibiotic is suspended in the composition;

(ii) the viscosity of the composition is at least about 30% higher than the viscosity of the carrier without the tetracycline antibiotic; and is higher than the viscosity of the hydrophobic oil and the tetracycline antibiotic without the viscosity modifying agents;

(iii) the amount of viscosity modifying agents can optionally be reduced by at least an amount by weight that would have increased the viscosity of the carrier without the tetracycline antibiotic by at least 30%;

wherein the tetracycline is chemically stable in the composition for at least six months wherein more than about 90% of the tetracycline has not broken down;

wherein when packaged in an aerosol container to which is added a liquefied or compressed gas propellant the composition affords upon release from the container a breakable foam of at least good quality that breaks easily upon application of shear force.

[0009] It is known in the art that foams can easily be formulated based on high amounts of water, in combination with surface active agents, foam adjuvants and polymeric agents. As described in the literature, hydrophobic solvents can have a de-foaming effect which makes the formulation of foams based on hydrophobic solvents - challenging. To overcome this challenge, the prior art requires the use of substantial levels of surfactants that act as foaming agents. Surface active agents are known to be irritating, especially ionic surface active agents and repeated use can cause dry skin and so it is desirable to reduce their use in pharmaceutical compositions intended to treat skin or mucosa. The prior art further teaches the incorporation of foam adjuvants, such as fatty alcohols and fatty acids, as foam boosting agents and also the incorporation of polymeric agents (e.g. gelling agents) as foam stabilizers, which can prolong the collapse time of a foam. Waxes may also be introduced into these surfactant based formulations but as will be appreciated, waxes, which are solids at ambient temperature, can easily precipitate.

[0010] The technical problems to be overcome in formulating oleaginous earners and pharmaceutical compositions with hydrophobic solvent (a) without surfactants; and/or (b) without polymeric agents and/or (c) without water and/or (e) without short chain alcohols and/or (f) without polyols; are multifold and include finding a suitable substitute for surfactant which provides foam generating properties; finding a suitable replacement that preferably does not need to have a foam adjuvant present with the surfactant (substitute), which if present would inter alia help to boost the foam and as an aid to the surfactant and preferably does not need to have a polymeric agent present with the surfactant (substitute), which if present would inter alia help prolong stability of the foam.

[0011] It was surprisingly discovered in the present invention, that surface active agents can be advantageously eliminated and replaced by viscosity-modifying agents consisting of a fatty alcohol, a fatty acid and a wax in the context of hydrophobic solvent based-foams.

Waxes possess several advantages over other foaming agents such as excellent skin compatibility, almost no chemical reactivity which ensures active ingredients stability and efficient skin occlusion which helps reducing skin water loss and can enhance skin penetration of active agents. Albeit waxes introduce their own additional problems into formulating foamable compositions and foams, including their tendency to solidify and precipitate out from a formulation and to block canister valves, against which the formulations need to be designed so that the formulations are not negatively disturbed upon adding an effective amount of propellant and that the formulations are shakable and are homogenous and can readily reform at least upon mild or reasonable shaking prior to use. [0012] Another challenge is how to adjust the rheology as primarily expressed in the viscosity of the formulation before and after adding propellant so that before it can exhibit gel like properties and that after addition it is shakable in the canister, Additionally the composition should be capable of generating a foam that when applied to a target is neither a liquid nor very viscous but is comfortable an convenient for application. Further, costs of toxicology and trials may be substantially reduced where the gel and the foam are capable of showing equivalency for pharmaceutical purposes.

[0013] Incorporated in or added to the above is the aspect of how to provide formulations in which unstable active ingredients, such as tetracyclines, which readily degrade can nevertheless remain sufficiently chemically stable for prolonged periods of time such that allowing for a reasonable or acceptable amount of breakdown (for example as may be accepted by a regulatory drug authority) they remain capable of providing a therapeutic effect or prevention or remission of a disorder or disease (hereinafter “chemically stable”). A further challenge is providing and delivering a composition in which the active agent is homogenous, especially when the active agent is not dissolved. Additionally the formulations should avoid the use of substances, which can be irritating if applied to a sensitive target or can cause depletion or drying or soreness on repeated use.

[0014] Incorporated in or added to the above is the aspect of how to provide physically stable formulations which are at least short term stable upon release from the pressurized container and not break as a result of exposure to skin temperature. Foams which are structurally stable on the skin for at least one minute are termed “short term stable”. In another aspect of physically stability the foamable formulation including propellant remains homogenous and does not separate to any significant extent for at least one minute after being shaken (hereinafter “physically stable”).

[0015] In one aspect, a topical therapeutic hydrophobic breakable composition includes a carrier comprising about 60% to about 99% by weight of at least one hydrophobic oil and at least one viscosity-modifying agents selected from the group consisting of a fatty alcohol, a fatty acid and a wax; and a tetracycline antibiotic, characterized in that at least part of the tetracycline antibiotic is suspended in the composition and the viscosity of the composition is at least about 30% higher than the viscosity of the carrier without the tetracycline antibiotic; and is higher than the viscosity of the hydrophobic oil and the tetracycline antibiotic without the viscosity modifying agents; and wherein after storage at 25°C for at least two months the composition retains at least 90% of the tetracycline initially present in the composition; and wherein when packaged in an aerosol container to which is added a liquefied or compressed gas propellant the composition affords upon release from the container a breakable foam of at least good quality that breaks easily upon application of shear force.

[0016] In one or more embodiments, the tetracycline at least 95% or at least 97% of the tetracycline initially present is present after at least two months.

[0017] In one or more embodiments, the tetracycline at least 90% or at least 95% or at least 97% of the tetracycline initially present is present after at least three months.

[0018] In one or more embodiments, the tetracycline at least 90% or at least 95% or at least 97% of the tetracycline initially present is present after at least six months.

[0019] In one or more embodiments, the amount of tetracycline present is determined by HPLC.

[0020] In one or more embodiments, the increase in viscosity is a synergistic increase such that the combined viscosity of the carrier and the viscosity of the hydrophobic oil and the tetracycline antibiotic is less than the viscosity of the composition.

[0021] In one or more embodiments, the hydrophobic breakable vehicle is in the form of a gel prior to addition of propellant; wherein said gel liquefies and spreads easily upon application of mild shear force.

[0022] In one or more embodiments, the hydrophobic breakable vehicle is in the form of a foam; wherein said foam has a collapse time of greater than about 3 minutes .

[0023] In one or more embodiments, the ratio of composition other than propellant to propellant is from about 100:1 to about 100:25.

[0024] In one or more embodiments, the at least one hydrophobic oil is selected from the group consisting of a mineral oil, a hydrocarbon oil, an ester oil, an ester of a dicarboxylic acid, a triglyceride oil, an oil of plant origin, an oil from animal origin, an unsaturated or polyunsaturated oil, a diglyceride, a PPG alkyl ether, an essential oil, a silicone oil, liquid paraffin, an isoparaffin, a polyalphaolefin, a polyolefin, polyisobutylene, a synthetic isoalkane, isohexadecane, isododecane, alkyl benzoate, alkyl octanoate, C12-C15 alkyl benzoate, C12-C15 alkyl octanoate, arachidyl behenate, arachidyl propionate, benzyl laurate, benzyl myristate, benzyl palmitate, bis (octyldodecyl stearoyl) dimer dilinoleate, butyl myristate, butyl stearate, cetearyl ethylhexanoate, cetearyl isononanoate, cetyl acetate, cetyl ethylhexanoate, cetyl lactate, cetyl myristate, cetyl octanoate, cetyl palmitate, cetyl ricinoleate, decyl oleate, diethyleneglycol diethylhexanoate, diethyleneglycol dioctanoate, diethyleneglycol diisononanoate, diethyleneglycol diisononanoate, diethylhexanoate, diethylhexyl adipate, diethylhexyl malate, diethylhexyl succinate, diisopropyl adipate, diisopropyl dimerate, diisopropyl sebacate, diisosteary dimer dilinoleate, diisostearyl fumerate, dioctyl malate, dioctyl sebacate, dodecyl oleate, ethylhexyl palmitate, ester derivatives of lanolic acid, ethylhexyl cocoate, ethylhexyl ethylhexanoate, ethylhexyl hydroxystarate, ethylhexyl isononanoate, ethylhexyl palmytate, ethylhexyl pelargonate, ethylhexyl stearate, hexadecyl stearate, hexyl laurate, isoamyl laurate, isocetyl isocetyl behenate, isocetyl lanolate, isocetyl palmitate, isocetyl stearate, isocetyl salicylate, isocetyl stearate, isocetyl stearoyl stearate, isocetearyl octanoate, isodecyl ethylhexanoate, isodecyl isononanoate, isodecyl oleate, isononyl isononanoate, isodecyl oleate, isohexyl decanoate, isononyl octanoate, isopropyl isostearate, isopropyl lanolate, isopropyl laurate, isopropyl myristate, isopropyl palmitate, isopropyl stearate, isostearyl behenate, isosteary citrate, isostearyl erucate, isostearyl glycolate, isostearyl isononanoate, isostearyl isostearate, isostearyl lactate, isostearyl linoleate, isostearyl linolenate, isostearyl malate, isostearyl neopentanoate, isostearyl palmitate, isosteary salicylate, isosteary tartarate, isotridecyl isononanoate, isotridecyl isononanoate, lauryl lactate, myristyl lactate, myristyl myristate, myristyl neopentanoate, myristyl propionate, octyldodecyl myristate, neopentylglycol dicaprate, octyl dodecanol, octyl stearate, octyl palmitate, octyldodecyl behenate, octyldodecyl hydroxystearate, octyldodecyl myristate, octyldodecyl stearoyl stearate, oleyl erucate, oleyl lactate, oleyl oleate, propyl myristate, propylene glycol myristyl ether acetate, propylene glycol dicaprate, propylene glycol dicaprylate, propylene glycol dicaprylate, maleated soybean oil, stearyl caprate, stearyl heptanoate, stearyl propionate, tocopheryl acetate, tocopheryl linoleate, glyceryl oleate, tridecyl ethylhexanoate, tridecyl isononanoate, triisocetyl citrate, alexandria laurel tree oil, avocado oil, apricot stone oil, barley oil, borage seed oil, calendula oil, canelie nut tree oil, canola oil, caprylic/capric triglyceride castor oil, coconut oil, com oil, cotton oil, cottonseed oil, evening primrose oil, flaxseed oil, groundnut oil, hazelnut oil, glycereth triacetate, glycerol triheptanoate, glyceryl trioctanoate, glyceryl triundecanoate, hempseed oil, jojoba oil, lucerne oil, maize germ oil, marrow oil, millet oil, neopentylglycol dicaprylate/dicaprate, olive oil, palm oil, passionflower oil, pentaerythrityl tetrastearate, poppy oil, propylene glycol ricinoleate, rapeseed oil, rye oil, safflower oil, sesame oil, shea butter, soya oil, soybean oil, sweet almond oil, sunflower oil, sysymbrium oil, syzigium aromaticum oil, tea tree oil, walnut oil, wheat germ glycerides, wheat germ oil, PPG-2 butyl ether, PPG-4 butyl ether, PPG-5 butyl ether, PPG-9 butyl ether, PPG-12 butyl ether, PPG-14 butyl ether, PPG-15 butyl ether, PPG-15 stearyl ether, PPG-16 butyl ether, PPG-17 butyl ether, PPG-18 butyl ether, PPG-20 butyl ether, PPG-22 butyl ether, PPG-24 butyl ether, PPG-26 butyl ether, PPG-30 butyl ether, PPG-33 butyl ether, PPG-40 butyl ether, PPG-52 butyl ether, PPG-53 butyl ether, PPG-10 cetyl ether, PPG-28 cetyl ether, PPG-30 cetyl ether, PPG-50 cetyl ether, PPG-30 isocetyl ether, PPG-4 lauryl ether, PPG-7 lauryl ether, PPG-2 methyl ether, PPG-3 methyl ether, PPG-3 myristyl ether, PPG-4 myristyl ether, PPG-10 oleyl ether, PPG-20 oleyl ether, PPG-23 oleyl ether, PPG-30 oleyl ether, PPG-37 oleyl ether, PPG-40 butyl ether, PPG-50 oleyl ether, PPG-11 stearyl ether, herring oil, codliver oil, salmon oil, cyclomethicone, a dimethyl polysiloxane, dimethicone, an epoxymodified silicone oil, a fatty acid-modified silicone oil,, a fluoro group-modified silicone oil, a methylphenylpolysiloxane, phenyl trimethicone and a polyether group-modified silicone oil.

[0025] In one or more embodiments, the fatty alcohol has at least 12 carbon atoms in its carbon backbone; and wherein said fatty acid has at least 12 carbon atoms in its carbon backbone.

[0026] In one or more embodiments, the fatty alcohol and said fatty acid have a melting point of more than about 40°C.

[0027] In one or more embodiments, the fatty alcohol is selected from the group consisting of lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol, tetracosanol, hexacosanol, octacosanol, triacontanol, tetratriacontanol; and wherein said fatty acid is selected from the group consisting of dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, eicosanoic acid, docosanoic acid, tetracosanoic acid, hexacosanoic acid, heptacosanoic acid, octacosanoic acid, triacontanoic acid, dotriacontanoic acid, tritriacontanoic acid, tetratriacontanoic acid and pentatriacontanoic acid.

[0028] In one or more embodiments, the carbon chain of said fatty alcohol or said fatty acid is substituted with a hydroxyl group, and for example, the carbon chain of said fatty acid is 12-hydroxy stearic acid.

[0029] In one or more embodiments, wax is selected from the group consisting of a plant wax, carnauba wax, candelilla wax, ouricury wax, sugarcane wax, retamo wax, jojoba oil, an animal waxes, beeswax, a petroleum derived wax, a paraffin wax, polyethylene and derivatives thereof.

[0030] In one or more embodiments, the viscosity-modifying agent is a combination comprising (i) at least one fatty alcohol and at least one fatty acid; or (ii) at least one fatty alcohol and least one wax; or (iii) at least one fatty acid and at least one wax; or (iv) at least one fatty alcohol, at least one fatty acid and least one wax.

[0031] In one or more embodiments, the hydrophobic breakable vehicle is substantially free of surface active agents, protic solvents, polar aprotic solvents and silicone thickening agents.

[0032] In one or more embodiments, the hydrophobic breakable vehicle is substantially free of surface active agents, polymeric gelling agents, polyols, short chain alcohols and silicone thickening agents.

[0033] In one or more embodiments, the hydrophobic breakable vehicle contains less than about 0.4%; or less than about 0.2%; or less than about 0.1% of surface active agents, protic solvents, polar aprotic solvents and silicone thickening agents.

[0034] In one or more embodiments, the tetracycline antibiotic is selected from the group consisting of tetracycline, oxytetracycline, demeclocycline, doxycycline, lymecycline, meclocycline, methacycline, minocycline, rolitetracycline, chlorotetracycline and tigecycline, and for example, the tetracycline antibiotic is hydrophobic.

[0035] In one or more embodiments, the tetracycline antibiotic is present in a free base form a hydrate form, a salt form or a complex form, and for example, the Log of the distribution constant of the tetracycline antibiotic at pH 7.0 (buffer/chloroform) is equal to or less than about 0.2.

[0036] In one or more embodiments, the tetracycline antibiotic does not comprise any hydroxy group at Carbons 5, 6, and 7, and for example, the tetracycline antibiotic is selected from the group of minocycline and doxycycline; or is minocycline.

[0037] In one or more embodiments, the composition further comprises an additional active agent.

[0038] In one or more embodiments, the additional active agent is selected form the group consisting of an active herbal extract, an acaricides, an age spot and keratose removing agent, an allergen, an alpha hydroxyl acid, an analgesic agent, an androgen, an antiacne agent, an antiallergic agent, an antiaging agent, an antibacterial agent, an antibiotic, an antibum agent, an anticancer agent, an antidandruff agent, an antidepressant, an antidermatitis agent, an antiedemic anent, an antifungal agent, an antihistamine, an antihelminth agent, an anti-hyperkeratosis agent, an anti-infective agent, an antiinflammatory agent, an antiirritant, an antilipemic agent, an antimicrobial agent, an antimycotic agent, an antioxidant, an antiparasitic agent, an antiproliferative agent, an antipruritic agent, an antipsoriatic agent, an antirosacea agent, an antiseborrheic agent, an antiseptic agent, an antiswelling agent, an antiviral agent, an anti-wart agent, an anti-wrinkle agent, an antiyeast agents, an astringent, a beta-hydroxy acid, benzoyl peroxide, a topical cardiovascular agent, a chemotherapeutic agent, a corticosteroid, an immunogenic substance, a dicarboxylic acid, a disinfectant, an estrogen, a fungicide, a hair growth regulator, a haptene, a hormone, a hydroxy acid, an immunosuppressant, an immunoregulating agent, an immunomodulator, an immunostimulant, an insecticide, an insect repellent, a keratolytic agent, a lactam, a local anesthetic agent, a lubricating agent, a masking agent, a metals, a metal oxide, a mitocide, a neuropeptide, a non-steroidal anti-inflammatory agent, an oxidizing agent, a pediculicide, a peptide, a pesticide, a protein, a photodynamic therapy agent, a progesterone, a radical scavenger, a refatting agent, a retinoid, a sanative, a scabicide, a sedative, a self tanning agent, a skin protective agent, a skin whitening agent, a steroid, a steroid hormone, a vasoactive agent, a vasoconstrictor, a vasodilator, a vitamin, a vitamin A, a vitamin A derivative, a vitamin B, a vitamin B derivative, a vitamin C, a vitamin C derivative, a vitamin D, a vitamin D derivative, a vitamin D analog, a vitamin F, a vitamin F derivative, a vitamin K, a vitamin K derivative, a wound healing agent and a wart remover.

[0039] In one or more embodiments, wherein, when tested in the Franz-cell in vitro model using human or pig’s skin, affords an amount of the tetracycline in the skin which is higher than the respective amount transferred transdermally.

[0040] In one or more embodiments, wherein, when tested in the Franz-cell in vitro model using human or pig’s skin, the ratio between the amount of the tetracycline in the skin and the respective amount transferred transdermally is higher than about 100:1 ;or between about 100:1 and about 10:1; or between about 10:1 and about 2:1; or more than 1:1.

[0041] In one or more embodiments, wherein the concentration of the tetracycline in the hydrophobic breakable composition is higher than the lowest concentration which results in intradermal delivery of sufficient concentrations of the tetracycline to have a therapeutic effect when tested in the Franz-cell in vitro model, using human or pig’s skin.

[0042] In one or more embodiments, wherein the composition prevents the degradation of the tetracycline antibiotic upon application on the target site of treatment.

[0043] In another aspect, a method of preventing, treating or alleviating the symptoms of a dermatological, an ophthalmological, a gynecologic or mucosal disorder includes applying topically to the target area a hydrophobic therapeutic composition as described herein.

[0044] In one or more embodiments, the disorder includes bacterial infection, inflammation, oxidative stress, and neurodgeneration and/or apoptosis as one of it etiological factors.

[0045] In one or more embodiments, the disorder is selected from the group consisting of a dermatological condition abscess, acne, acne conglobata, acne fulminans, acne vulgaris, acne scars, acute febrile neutrophilic dermatosis, acute lymphangitis, allergic contact dermatitis, alopecia, athlete's foot, atopic dermatitis, bacterial skin infections, baldness, basal cell carcinoma, blisters, bromhidrosis, bullous pemphigoid, bum, calluses candidiasis, carbuncles, cellulitis, chemical bums, chicken pox, cholesteatoma, cholinergic urticaria, chronic effects of sunlight, cold sores, cold urticaria, comedones, coms, creeping eruption, cutaneous abscess, cutaneous larva migrans, cutaneous myiasis, dark spots, delusional parasitosis, Dercum disease, dermatitis, dermatitis herpetiformis, dermatological pain, dermatological inflammation, dermographism, dermatophytoses, drug eruptions and reactions, dyshidrotic eczema, ectodermal dysplasia, eczema, ecthyma, epidermoid cyst, epidermal necrolysis, erysipelas, erysipelas, erythrasma, exfoliative dermatitis, erythema multiforme, erythema nodosum, folliculitis, fungal nail infections, fungal skin infections, furuncles, gangrene, genital herpes, granuloma annulare, head lice, hidradenitis suppurativa, hives, folliculitis, hirsutism, hyperhidrosis, hypohidrosis, ichthyosis, impetigo, inflammatory acne, ingrown nails, intertrigo, irritant contact dermatitis, ischemic necrosis, itching, jock itch, Kaposi's sarcoma, keratosis pilaris, lichen simplex chronicus, lichen planus, lichen sclerosus, lymphadenitis, lymphadenitis, lymphangitis, malignant melanoma, mastocytosis, measles, melanoma, melanoma, miliaria, moles, molluscum contagiosum, MRSA, necrotizing subcutaneous infection, necrotizing fasciitis, necrotizing myositis, nodular papulopustular acne, non-inflammatory acne, nummular dermatitis, oral herpes, panniculitis, parapsoriasis paronychia, parasitic skin infections, pemphigus, photo-allergy, photo-damage, photo-irritation, photosensitivity, papules, pediculosis, perioral dermatitis, pimples, pityriasis rosea, pityriasis Lichenoides, pityriasis rosea, pityriasis rubra pilaris, poison ivy, postoperative or post-surgical skin conditions, pressure ulcers, pressure urticaria, pruritis, pseudo folliculitis barbae, psoriasis, PUPPP, purpura, pustules, pyogenic granuloma, rash, ringworm, rosacea, roseola, rubella, scabies, scalded skin syndrome, scarring, scleroderma, sebaceous cyst, seborrheic dermatitis, seborrheic keratosis, shingles, skin aging, skin cancer, skin neoplasia, skin neoplasms, skin rash, skin ulcers, squamous cell carcinoma, staphylococcal scalded skin syndrome, stasis dermatitis, Stevens-Johnson syndrome, sunburn, sun spots, thermal bums, tinea corporis, tinea cruris, tinea pedis, tinea versicolor, toxic epidermal necrolysis, trauma or injury to the skin, varicella zoster virus, vitamin D deficiency, viral skin infections, vitiligo, warts, water hives, wrinkles, xerosis, yeast skin infections and zoster; a disorder of a body cavity or mucosal surface, a disorder of the nose, mouth, eye, ear, respiratory system, vagina, urethra, or rectum, chlamydia infection, gonorrhea infection, hepatitis B, herpes, HIV/AIDS, human papillomavirus (HPV), genital warts, bacterial vaginosis, candidiasis, chancroid, granuloma Inguinale, lymphogranloma venereum, mucopurulent cervicitis (MPC), molluscum contagiosum, nongonococcal urethritis (NGU), trichomoniasis, vulvar disorders, vulvodynia, vulvar pain, yeast infection, vulvar dystrophy, vulvar intraepithelial neoplasia (VIN), contact dermatitis, pelvic inflammation, endometritis, salpingitis, oophoritis, genital cancer, cancer of the cervix, cancer of the vulva, cancer of the vagina, vaginal dryness, dyspareunia, anal and rectal disease, anal abscess/fistula, anal cancer, anal fissure, anal warts, Crohn's disease, hemorrhoids, anal itch, pruritus ani, fecal incontinence, constipation, polyps of the colon and rectum; an ophthalmic disorder, eye redness, eye pain or light sensitivity, blurred vision, loss of vision, visual disturbances - floaters, flashing, distortion, halos, etc., itching / burning, tearing / discharge, sensation of something in the eye, eyelid problems, double vision; ophtahlmic allergy, blepharitis, cataract, central serous chorioretinopathy, color vision problems, comeal abrasion, comeal edema, comeal ulcer, conjunctivitis, contact lens complications, dacryocystitis, blurred distance vision, dry eye, eale's disease, episcleritis, eyelid ectropion, eyelid entropion, eyelid cellulitis, eye strain, focusing spasm, glaucoma, acute glaucoma, iritis, keratoconus, lyme disease, macular degeneration, macular edema, macular hole, eye medication toxicity, myasthenia gravis, ocular cicatricial pemphigoid, ophthalmic migraine, presbyopia, obstructed tear duct, optic neuritis, optic nerve stroke, orbital fracture, orbital cellulitis, phlyctenulosis, pterygium, recurrent comeal erosion, retinal artery occlusion, retinal detachment, retinal tear, retinal vein occlusion, sarcoidosis, scleritis, sinus disease, strabismus (ocular misalignment), subconjunctival hemorrhage, temporal arteritis, thyroid eye disease, trichiasis, eyelid tumor, twitching of eyelid (eyelid myokymia), uveitis, vitreous detachment and vitreous hemorrhage.

[0046] In one or more embodiments, the disorder is selected from the group consisting of a skin infection, acne, rosacea, an eye infection, ocular rosacea, blepharitis, dry eye, trachoma and glaucoma.

[0047] In one or more other specific embodiments the drug carrier is formulated substantially free of elastomers. In one or more other specific embodiments the drug carrier is formulated essentially free of elastomers. In one or more other specific embodiments the drug carrier is formulated substantially free of silicones. In one or more other specific embodiments the drug carrier is formulated essentially free of silicones. In one or more other specific embodiments the drug carrier is formulated with less than about 30% silicone, or less than about 25% silicone, or less than about 20% silicone, or less than about 15% silicone, or less than about 10% silicone, or less than about 7.5% silicone, or less than about 5% silicone or less than about 2% silicone; or less than about 1% silicone; or less than about 0.5% silicone.

DETAILED DESCRIPTION

[0048] The present invention is directed to a hydrophobic breakable tetracycline formulation for topical administration, wherein the formulation is (i) in the form of an oil gel that liquefies and spreads easily upon application of mild shear force; or (ii) an oil foam; wherein said oil foam is stable upon dispensing from the aerosol can and breaks down and spreads easily upon application of mild shear force.

[0049] The formulation of the invention is suitable for topical administration to the skin and mucosal membranes, the eyes, nasal cavity, the ear canal and the vaginal cavity.

[0050] A feature of a product for medical use is long term stability. The compositions herein are surprisingly stable. Following accelerated stability studies, they demonstrate desirable texture, do not break immediately upon contact with a surface, spread easily on the treated area and absorb quickly.

[0051] In one or more embodiments the composition has an acceptable shelf-life of at least six months. In one or more embodiments the foam composition has an acceptable shelflife of at least one year, In one or more embodiments the foam composition has an acceptable shelf-life of at least 15 months, or at least 18 months or at least 21 months or at least two years at ambient temperature.

[0052] In one or embodiments stability is inter alia a product of extensive effort and research; eliminating surfactants; eliminating water; choice of components; testing each component individually with the active agent (compatibility studies); the combination of components, having an appropriate Aw value (e.g.<9), storage in an air and light tight container.

[0053] In one or more embodiments the active agent is considered chemically stable when more than about 90% of the active agent does not break down after a period of two months in the formulation at room temperature. In one or more embodiments the period is six months. In one or more embodiments more than about 88% of the active agent does not break down. In one or more embodiments the active agent is chemically stable in the composition at 40 °C.

[0054] In one or more embodiments the drug carrier is formulated substantially free of short chain alcohols, such as, ethanol, propanol or butanol. In one or more embodiments the drug carrier is formulated essentially free of short chain alcohols. In one or more specific embodiments the drug carrier is formulated essentially free of derivatives of fatty alcohols or fatty acids. In one or more other specific embodiments the drug carrier is formulated essentially free of polyols. In one or more other specific embodiments the drug carrier is formulated substantially free of surfactants and or short chain alcohols and or polyols. In one or more other specific embodiments the drug carrier is formulated essentially free of surfactants and or short chain alcohols and or polyols. In one or more embodiments there is provided a composition which is essentially waterless. In one or more embodiments there is provided a surfactant free composition that is also free of short chain alcohols and or polyolfree. In one or more embodiments there is provided a substantially polymer free composition. In other embodiments it is essentially polymer free. In still further embodiments the composition is free of polymeric agent. In one or more embodiments a polymeric agent has a Molecular weight of at least about 1000 Daltons.

[0055] In one or more embodiments the composition is essentially free of two or more of water; polymeric agent; surfactant; short chain alcohol; or polyol. In one or more embodiments the composition is essentially free of three or more of water; polymeric agent; surfactant; short chain alcohol; or polyol. In one or more embodiments the composition is essentially free of four or more of water; polymeric agent; surfactant; short chain alcohol; or polyol. In one or more embodiments the composition is essentially free of water; polymeric agent; surfactant; short chain alcohol; and polyol.

[0056] In one or more other specific embodiments the drug carrier is formulated substantially free of elastomers. In one or more other specific embodiments the drug carrier is formulated essentially free of elastomers. In one or more other specific embodiments the drug carrier is formulated substantially free of silicones. In one or more other specific embodiments the drug carrier is formulated essentially free of silicones. In one or more other specific embodiments the drug carrier is formulated with less than about 30% silicone, or less ΡϋΤ/ΓΒ2010/002617 than about 25% silicone, or less than about 20% silicone, or less than about 15% silicone, or less than about 10% silicone, or less than about 7.5% silicone, or less than about 5% silicone or less than about 2% silicone; or less than about 1% silicone; or less than about 0.5% silicone.

Definitions

[0057] All % values are provided on a weight (w/w) basis.

[0058] In one or more embodiments wherever a phrase is used to refer to a concentration of above X% or below X% it can also include X% or above about X% or below about X% it can also include about X%.

[0059] In one or more embodiments the term “about” has its usual meaning in the context of pharmaceutical and cosmetic formulations to allow for reasonable variations in amounts that can achieve the same effect. By the term “about” herein it is meant as indicated above and also that a figure or range of figures can vary in an embodiments plus or minus up to 30%. So in this embodiment if a figure of “about 1” is provided then the amount can be up to 1.3 or from 0.70. In other embodiments it can reflect a variation of plus or minus 20%. In still further embodiments it can describe a variation of plus or minus 10%. In still further embodiments it can describe a variation of plus or minus 5%. As will be appreciated by one of the art there is some reasonable flexibility in formulating compositions such that where one or more ingredients are varied successful formulations may still be made even if an amount falls slightly outside the range. Therefore, to allow for this possibility amounts are qualified by about. In one or more other embodiments the figures may be read without the prefix about.

[0060] The term “thixotropic,” as used herein, means that the formulation shows a significant decrease in viscosity upon application of shear force.

[0061] The term “waterless,” as used herein, means that the composition contains no, or substantially no, free or unassociated or absorbed water. Similarly, “waterless” or “substantially waterless” carriers contain at most incidental and trace amounts of water.

[0062] By the term “single phase” herein it is meant that the liquid components of the composition or carrier are fully miscible, and the solid components if any, are either dissolved or suspended in the composition. By substantially a single phase is meant that the composition or carrier is primarily or essentially a single phase as explained above, but may also have present a small amount of material which is capable of forming or may form a separate phase amounting to less than about 5% of the composition or carrier, preferably less than about 3%, and more preferably less than about 1%. By the term “single phase” or “substantially a single phase” in the context of a foamable composition the above meaning applies even after addition of propellant to the composition or carrier.

[0063] The term “unstable active agent” as used herein, means an active agent which is oxidized and/or degraded within less than a day, and in some cases, in less than an hour upon exposure to air, light, skin or water under ambient conditions.

[0064] The term “co-surfactant” as used herein, means a compound which on its own is not able to form and stabilize satisfactorily an oil in water emulsion, but when used in combination with a surfactant, such co-surfactant can boost the emulsifying power of surfactants to create a stable emulsion. For example, fatty alcohols, such as cetyl alcohol or a fatty acid such as stearic acid can function as co-surfactants. Cetyl alcohol and stearyl alcohol are waxy hydrophobic substances that can be emulsified with water using a surfactant. In certain circumstances a co-surfactant can itself be converted in to a surfactant or soap by, for example, adding a base, such as, triethanolamine to a fatty acid, resulting in a fatty acid salt, which is also termed “soap” (a strong anionic surfactant).

[0065] The identification of a “polyol”, as used herein, is an organic substance that contains at least two hydroxy groups in its molecular structure.

Gel and Foam Presentations

[0066] The topical therapeutic hydrophobic breakable composition of the present invention can be presented as a gel or as a foam. The term “breakable”, as used herein relates to a composition is stable as a gel or as a foam upon dispensing from a container, yet breaks and spreads easily upon application of mild shear force.

[0067] It was surprisingly discovered in the present invention, that certain compositions comprising a hydrophobic solvent, together with viscosity-modifying agents which may be at least one fatty alcohol and/or at least one fatty acid, and/or at least one wax and mixtures of two or more thereof; and a suspended active agent; without any surface active agents afford, upon packaging in an aerosol container and adding a propellant, a shakable and homogenous foamable composition, which releases a breakable foam with good to excellent quality (as defined herein.

[0068] The resulting foam is pharmaceutically equivalent to the respective gel (prior to adding the propellant), since immediately upon dispensing of the foam the propellant evaporates and the composition upon administration is similar to that of the gel. This is an important pragmatic advantage, because many drug development activities, including expensive and lengthy toxicology studies with numerous animals and clinical trials with thousands of patients can be saved by conducting such studies once for the gel and foam presentation instead of twice (for each presentation).

Gel

[0069] The primary essential components the gel of the present invention comprises (a) at least one hydrophobic oil, (b) at least one viscosity-modifying agent and (c) a tetracycline antibiotic. The concentration of the hydrophobic oil is between about 60% and about 99% by weight. In one or more other embodiments the concentration is between about 60% and about 95%, or is between about 65% and about 99%, or is between about 65% and about 95%, or is between about 70% and about 95%, or is between about 75% and about 95%, or is between about 80% and about 95%, or is between about 85% and about 99%, or is between about 85% and about 95%.

[0070] Surprisingly, we discovered that, while the addition of the viscosity-modifying agents to the hydrophobic oil increased the viscosity of such oil, even small amounts of a suspended tetracycline antibiotic increased the viscosity of the composition synergistically. The gel is stable and it retains its viscosity upon dispensing from a container, such as a tube, yet, it liquefies and spreads easily upon application of mild shear force. Further, whilst the gel is oily, it readily absorbs into the site of application such as the skin, and after a few minutes the surface looks and feels free of any oiliness or greasiness.

[0071] The combination of a tetracycline with a mixture of one or more hydrophobic oils, fatty alcohols, fatty acids and waxes has a strong synergistic effect and increases the formulation viscosity. For example, the viscosity of a formulation containing 0.50% minocycline HC1 is about three times higher than the viscosity of the same formulation without the tetracycline. The effect on the formulation viscosity is directly related to the concentration of the tetracycline: the higher the tetracycline concentration, the higher the viscosity of the formulation. In certain cases, it appeared that the viscosity increasing effect of minocycline HC1 reaches a plateau when the active ingredient is present at a concentration of about 0.50% or, in certain embodiments, when the viscosity of the carrier is in excess of about 25,000cps.

[0072] Thus, in one or more embodiments, there is provided a gel containing at least one hydrophobic oil and a tetracycline in a synergistic combination with a fatty alcohol, and/or a fatty acid and/or a wax, wherein the viscosity of the formulation is increased by the addition of the active ingredient by more than about 30%, or more than about 50%, or more than about

100%, or more than about 200%, or more than about 300%, or more than about 500%.

[0073] In one or more embodiments, the increase in the formulation viscosity is correlated with the concentration of the active agent.

[0074] In one or more embodiments, the viscosity of the formulation is directly proportional to the concentration of the active agent: the higher the concentration of the active ingredient, the higher the formulation viscosity.

[0075] In one or more embodiments, the viscosity increasing effect of the active ingredient reaches a plateau when the concentration of the active ingredient is increased. [0076] In one or more embodiments, the viscosity of the formulation containing the tetracycline is twice the viscosity of the sample formulation when the active ingredient is present at a concentration of less than about 10%, less than about 5%, less than about 1%, less than about 0.5%, less than about 0.1%, less than about 0.05%, less than about 0.01%. [0077] In one or more embodiments the viscosity of the gel is higher than about 10000 cPs; or between about 1000 cPs and about 100000 cPs; or between about 5000 cPs and about 50000 cPs; or between about 10000 cPs and about 30000 cPs.

[0078] In one or more embodiments the increase in viscosity of the composition is at least about 100% and viscosity of the carrier is less than about 12,000 cPs; or less than about 8,000 cPs; or less than about 2,000 cPs. In one or more embodiments the viscosity of the carrier is more than about 1,000 cPs; or more than about 1,300 cPs; or more than about 1,500 cPs. or more than about 1,800 cPs or more than about 2000 cPs. In one or more embodiments the viscosity of the carrier is more than about 150 cPs; or more than about 300 cPs, or more than about 500 cPs or more than about 800 cPs.

[0079] In one or more embodiments the change in viscosity is between about 50% and about 100%. In one or more embodiments the change in viscosity is between about 100% and about 500%. In one or more embodiments the change in viscosity is between about 500% and about 1000%. In one or more embodiments the change in viscosity is between about 1000% and about 1500%. In one or more embodiments the change in viscosity is between about 1500% and about 2000%. In one or more embodiments the change in viscosity is between about 2000% and about 2500%. In one or more embodiments the change in viscosity is between about 50% and about 3000%. In one or more embodiments the change in viscosity is in a range between about 150% and about 1000%. In one or more embodiments the change in viscosity is in a range between about 1000% and about 2500%In one or more embodiments the change in viscosity is between about 100% and about 2500%; about 100% and about

2000%; about 100% and about 1500%; or about 100% and about 1000%.

[0080] The gel composition has the unique property of stabilizing the tetracycline antibiotic and protecting it from degradation. For example, when a gel, containing about 83% hydrophobic oils, about 4.5% waxes, about 6% fatty alcohols and 5% fatty acid and about 1% micronized minocycline HC1 was applied to freshly retrieved and moist skin and stored on a Petri dish, with exposure to air and light for 6 hours the product remained substantially stable. Furthermore, even when a specimen of a hydrophobic gel with 1% minocycline was applied to a skin and exposed to direct sun light for two days, there was no apparent degradation, as shown by the conservation of the skin color. As tetracycline antibiotics, and especially minocycline are know to be susceptible to degradation by air, water and light, this protection effect is unique.

[0081] In an additional observation, while the minocycline was protected from the environmental factors (moisture light and air), it is not hindered or tightly encapsulated, as demonstrated by its efficient release into the skin in an in-vitro Franz cell model, an antibacterial test model and an anti-inflammation model, as further exemplified herein.

Foam

[0082] One skilled in the art would expect that a surfactant should be required in order to facilitate the production of foam.

[0083] However, surprisingly, when the gel composition described above, comprising (a) at least one hydrophobic oil, (b) at least one viscosity-modifying agent, and (c) a tetracycline antibiotic is introduced into an aerosol can, closed with an aerosol valve and pressurized with a propellant, it creates a breakable foam, i.e., a foam which is stable upon dispensing from a container, yet breaks and spreads easily upon application of mild shear force. As in the case of the gel, the foam it readily absorbs into the site of application such as the skin, and after a few minutes the surface looks and feels free of any oiliness or greasiness.

Foaming propellant

[0084] Examples of suitable propellants include compressed gases, volatile hydrocarbons such as butane, propane, isobutane and fluorocarbon gases, or mixtures thereof.

[0085] In an embodiment, the propellant is hydrophobic and it miscible with the oils in the composition.

[0086] In certain embodiments, fluoro-hydrocarbon propellants, other than chloro-fluoro carbons (CFCs) which are non-ozone-depleting propellants, are particularly useful in the production of a non-flammable foamable composition.

[0087] Such propellants include, but are not limited to hydrofluorocarbon (HFC) propellants, that contain no chlorine atoms, and as such, falls completely outside concerns about stratospheric ozone destruction by chlorofluorocarbons or other chlorinated hydrocarbons. Exemplary non-flammable propellants according to this aspect of the invention include propellants made by DuPont under the registered trademark Dymel, such as 1,1,1,2 tetrafluorethane (Dymel 134), and 1,1,1,2,3,3,3 heptafluoropropane (Dymel 227), 1,1, difluoro ethane (Dymel 152) and 1,1,1,3,3,3 hexafluoropropane. HFCs possess Ozone Depletion Potential of 0.00 and thus, they are allowed for use as propellant in aerosol products.

[0088] Yet, in additional embodiments, the propellant is a self-foaming propellant, i.e., a volatile liquid having a boiling point of less than the temperature of the target treatment site (such as the skin). An example of a post-foaming propellant is isopentane (bp=26°C) [0089] In an embodiment, the ratio of composition other than propellant to propellant is between about 100:1 to about 100:25, or is between about 100:3 to about 100:30, or is between about 100:5 to about 100:20 or is between about 100:8 to about 100:16, or between about 100:20 and about 100:50.

[0090] In one or more embodiments a foam formulation can be expelled or helped to be expelled by using propellant which is separate from the formulation using, for example, a bag on valve (BOV) or can in can aerosol system. A BOV system consists of the aerosol valve with a welded bag. With the BOV system compressed air or other propellants are introduced in the aerosol can on the outside of the bag and acts as a propellant on the product which is inside the bag. Using such a system makes it possible to reduce the amount of propellant within the formulation but still enable expulsion from the canister of a foam with desirable qualities. So by way of example, the concentration of the propellant in the bag is between about 1% to 3%; or between about 2% to 4%; between about 3% to 5% (ratio of formulation to propellant of 100:1 to 100:3; 100:2 to 100:4; 100: 3 to 5; respectively.

Foam properties

[0091] A foamable composition manufactured according to one or more embodiments herein is very easy to use. When applied onto the afflicted body surface of mammals, i.e., humans or animals, it is in a foam state, allowing free application without spillage. Upon further application of a mechanical force, e.g., by rubbing the composition onto the body surface, it freely spreads on the surface and is rapidly absorbed.

[0092] In one or more embodiments the foamable composition is a single phase solution. In one or more embodiments the foamable composition is substantially a single phase solution. In certain circumstances, where the active agent is insoluble and is presented as a homogenous suspension, the formulation is turbid or cloudy.

[0093] In one or more embodiments the foam composition has an acceptable shelf-life of at least one year, or at least two years at ambient temperature. A feature of a product for cosmetic or medical use is long term stability. Propellants, which are a mixture of low molecular weight hydrocarbons, or HFCs, tend to impair the stability. The foamable compositions herein are surprisingly stable, even in the absence of surfactants. Following accelerated stability studies, they demonstrate desirable texture; they form fine bubble structures that do not break immediately upon contact with a surface. They spread easily on the treated area and absorb quickly.

[0094] The composition should also be free flowing, to allow it to flow through the aperture of the container, e.g., and aerosol container, and create an acceptable foam. Compositions containing a substantial amount of semi-solid hydrophobic oils, e.g., white petrolatum, as the main ingredients of the oil phase of the emulsion, will likely exhibit high viscosity and poor flowability and can be inappropriate candidates for a foamable composition. Thus in one or more embodiments semi-solid hydrophobic oils are a subsidiary component in the composition, for example being present at less than about 25%, less than about 20%, less than about 15% , less than about 10%, or less than about 5% by weight of the foamable composition. In other embodiments they can be present in higher amounts due to the solvent effect of the propellant diluting the formulation and enabling flowability or where the formulation is presented as a gel or ointment or when solvents are added that reduce the viscosity such as alkyl benzoates.

Foam Quality

[0095] Foam quality can be graded as follows:

Grade E (excellent): very rich and creamy in appearance, does not show any bubble structure or shows a very fine (small) bubble structure; does not rapidly become dull; upon spreading on the skin, the foam retains the creaminess property and does not appear watery.

Grade G (good): rich and creamy in appearance, very small bubble size, dulls more rapidly than an excellent foam, retains creaminess upon spreading on the skin, and does not become watery.

Grade FG (fairly good): a moderate amount of creaminess noticeable, bubble structure is noticeable; upon spreading on the skin the product dulls rapidly and becomes somewhat lower in apparent viscosity.

Grade F (fair): very little creaminess noticeable, larger bubble structure than a fairly good foam, upon spreading on the skin it becomes thin in appearance and watery.

Grade P (poor): no creaminess noticeable, large bubble structure, and when spread on the skin it becomes very thin and watery in appearance.

Grade VP (very poor): dry foam, large very dull bubbles, difficult to spread on the skin.

[0096] Topically administrable foams are typically of quality grade E or G, when released from the aerosol container. Smaller bubbles are indicative of a more stable foam, which does not collapse spontaneously immediately upon discharge from the container. The finer foam structure looks and feels smoother, thus increasing its usability and appeal.

Foam Density

[0097] Another property of the foam is specific gravity or density, as measured upon release from the aerosol can. Typically, foams have specific gravity of less than 0.5 g/mL; or less than 0.3 g/mL; or less than 0.2 g/mL; or less than 0.1 g/mL, depending on their composition and on the propellant concentration. In one or more embodiments the foam density is about less than 0.3 g/mL.

Shakability

[0098] ‘Shakability’ means that the composition contains some or sufficient flow to allow the composition to be mixed or remixed on shaking. That is, it has fluid or semi fluid properties. Shakability is described further in the section on Tests. In one or more certain limited embodiments the formulation is poorly shakable but is nevertheless flowable.

Breakability / collapse time

[0099] A further aspect of the foam is breakability. The balance between stability and breakability of the foam coming out of the container is very delicate: on one hand the foam should preferably not be “quick breaking”, i.e., it should be stable upon release from the pressurized container and not break as a result of exposure to skin temperature; and on the other hand, it should be “breakable”, i.e., it should spread easily, break down and absorb into the skin or membrane upon application of mild shear force. The breakable foam is thermally stable, yet breaks under shear force. Shear-force breakability of the foam is clearly advantageous over thermally-induced breakability. Thermally sensitive foams can start to collapse immediately upon exposure to skin temperature and, therefore, cannot be applied on the hand and afterwards delivered to the afflicted area.

[0100] The collapse time of foam represents its tendency to be temperature-sensitive and its ability to be at least stable in the short term so as to allow a user sufficient time to comfortably handle and apply the foam to a target area without being rushed and or concerned that it may rapidly collapse, liquefy and or disappear. Collapse time, as an indicator of thermal sensitivity, is examined by dispensing a given quantity of foam and photographing sequentially its appearance with time during incubation at 36°C. Simple collapse time can be measured by applying a foam sample on a body surface like the fingers at normal body temperature of about 37°C

[0101] Oils may cause foam to be thennolabile and “quick breaking.” However, in certain embodiments herein, despite the presence of high oil content, quite unexpectedly the foam is substantially thermally stable. By “substantially thermally stable” it is meant that the foam upon application onto a warm skin or body surface at about 35-37°C does not collapse within about 30 seconds. Thus, in one or more embodiments the simple collapse time of the foam is more than about 30 seconds or more than about one minute or more than about two minutes. In one or more limited embodiments simple collapse time can be a little shorter than 30 seconds, but not less than about 20 seconds. In one or further or alternative embodiments the collapse time is measured by introducing a sample of foam into an incubator at 36°C and the collapse time of the foam is more than 30 seconds or more than about one minute or more than about two minutes.

Water activity

[0102] The term “water activity” as used herein, activity represents the hydroscopic nature of a substance; or the tendency of a substance that absorbs water from its surroundings. Microorganisms require water to grow and reproduce, and such water requirements are best defined in terms of water activity of the substrate. The water activity of a solution is expressed as Aw = P/Po, where P is the water vapor pressure of the solution and Po is the vapor pressure of pure water at the same temperature. Every microorganism has a limiting Aw, below which it will not grow; e.g., for Streptococci, Klebsiella spp, Escherichia coli, Clostridium perfringens, and Pseudomonas spp, the Aw value is 0.95. Staphylococcus aureus is most resistant and can proliferate with an Aw as low as 0.86, and fungi can survive at Aw of at least 0.7. In one or more embodiments, the concentration of the hydrophobic oil in the gel or foam composition is sufficient to provide an Aw value selected from the ranges of (1) about 0.8 and about 0.9; (2) about 0.7 and about 0.8; and (3) less than about 0.7. By delivering the formulation in a pressurized package does not allow for humidity to be absorbed by the preparation, and therefore, the water free character of the composition cannot be damaged.

Tetracycline

[0103] The primary active agent in accordance with the present invention is a tetracycline compound (herein “a tetracycline” or “tetracyclines”) or a pharmaceutically acceptable salt or hydrate thereof substantially stabilized in a base. The tetracyclines are characterized by a carbon skeleton composed of four linearly fused six-membered carbon rings (octahydrotetracene-2-carboxamide Skeleton). They are defined as a subclass of polyketides having an octahydrotetracene-2-carboxamide skeleton. They are collectively known as derivatives of polycyclic naphthacene carboxamide.

[0104] Non-limiting examples of tetracyclines, include the naturally-occurring Tetracycline, Chlortetracycline, Oxytetracycline and Demeclocycline, the semi-synthetic Doxycycline, Lymecycline, Meclocycline, Methacycline, Minocycline, Rolitetracycline, Chloro tetracycline and Tigecy cline.

[0105] The tetracyclines can be present in a free base form a hydrate form, a salt form or a complex form. For example, minocycline can be present as the base form, as well as a hydrate or a hydrochloride salt.

[0106] Notably, various tetracyclines have different hydrophilic/hydrophobic characters.

For example, the Log Kp (log of the of distribution constant at pH 7.0; buffer/CHC13) is 1.91, which means that it is highly hydrophilic. The Log Kp of Doxycycline is 0.2; and the Log Kp of Minocycline is -1.6, which stands for hydrophobic character of this compound (see Leive L et al, “Tetracyclines of various hydrophobicities as a probe for permeability of Escherichia coli outer membrane”, Antimicrobial Agents and Chemotherapy 1984:25, 539544). Whilst any tetracycline compound is suitable as an active agent according to the present invention, there is preference to tetracycline compounds which are more hydrophobic. Thus, in an embodiment of the present invention the active agent is selected as one that has Log Kp equal to, or lower than about 0.2.

[0107] In an embodiment, the tetracycline antibiotic is hydrophobic due to the fact that it does not comprise any hydroxy group at Carbons 5,6, and 7.

[0108] In certain embodiments, the tetracycline is selected from the group consisting of doxycycline and minocycline; and in a certain embodiment the tetracycline is minocycline. [0109] According to the present invention, the tetracycline is employed in an amount ranging from about 0.001% to about 10%; or in an amount ranging from about 0.025% to about 6%; or in an amount ranging from about 0.1% to about 3%, by weight of the foamable composition.

[0110] The tetracycline in accordance to the present invention is insoluble or is partially soluble in the whole composition and all or part thereof is suspended. It is known that every chemical compound has different solubility in different solvents or compositions, and therefore it is not possible to provide a general list compounds that are not soluble or partially soluble or suspended in the composition. However, any tetracycline active agent, as exemplified herein, is suitable as insoluble or partially soluble or suspended, if visual or microscopic observation demonstrates crystals or particles of such active agent in the oleaginous composition.

[0111] In additional embodiments, the concentration of the tetracycline is determined by its ability to inhibit the occurrence of apoptosis in an ex-vivo human skin model; or by its ability to inhibit the occurrence of pro-inflammatory cytokines in an ex-vivo human skin model. In alternate embodiments, the concentration of the tetracycline is higher than the lowest concentration which results in intradermal delivery of sufficient concentrations of the tetracycline when tested in the Franz-cell in vitro model, using human or pig’s skin.

Hydrophobic oil

[0112] The term “hydrophobic oil” relates to a material, having solubility in distilled water at ambient temperature of less than about 1 gm per 100 mL, or less than about 0.5 gm per 100 mL, or less than about 0.1 gm per 100 mL. The hydrophobic oil is a liquid at ambient (room) temperature, e.g., about 20-30°C.

[0113] In an embodiment, the topical therapeutic composition comprises at least one hydrophobic oil, selected from the group consisting of a mineral oil, a hydrocarbon oil, an ester oil, a triglyceride oil, an oil of plant origin, an oil from animal origin, an unsaturated or polyunsaturated oil, a diglyceride, a PPG alkyl ether and a silicone oil.

[0114] As exemplified herein, members of each of the above listed groups of hydrophobic oils have been found to be compatible with hydrophobic tetracyclines, such as minocycline and doxycycline.

[0115] Non-limiting examples of hydrocarbon oils include mineral oil, liquid paraffin, an isoparaffin, a polyalphaolefin, a polyolefin, polyisobutylene, a synthetic isoalkane, isohexadecane and isododecane.

[0116] Non-limiting examples of ester oils include alkyl benzoate, alkyl octanoate, Cl2C15 alkyl benzoate, C12-C15 alkyl octanoate, arachidyl behenate, arachidyl propionate, benzyl laurate, benzyl myristate, benzyl palmitate, bis (octyldodecyl stearoyl) dimer dilinoleate, butyl myristate, butyl stearate, cetearyl ethylhexanoate, cetearyl isononanoate, cetyl acetate, cetyl ethylhexanoate, cetyl lactate, cetyl myristate, cetyl octanoate, cetyl palmitate, cetyl ricinoleate, decyl oleate, diethyleneglycol diethylhexanoate, diethyleneglycol dioctanoate, diethyleneglycol diisononanoate, diethyleneglycol diisononanoate, diethylhexanoate, diethylhexyl adipate, diethylhexyl malate, diethylhexyl succinate, diisopropyl adipate, diisopropyl dimerate, diisopropyl sebacate, diisosteary dimer dilinoleate, diisostearyl fumerate, dioctyl malate, dioctyl sebacate, dodecyl oleate, ethylhexyl palmitate, ester derivatives of lanolic acid, ethylhexyl cocoate, ethylhexyl ethylhexanoate, ethylhexyl hydroxystarate, ethylhexyl isononanoate, ethylhexyl palmytate, ethylhexyl pelargonate, ethylhexyl stearate, hexadecyl stearate, hexyl laurate, isoamyl laurate, isocetyl isocetyl behenate, isocetyl lanolate, isocetyl palmitate, isocetyl stearate, isocetyl salicylate, isocetyl stearate, isocetyl stearoyl stearate, isocetearyl octanoate, isodecyl ethylhexanoate, isodecyl isononanoate, isodecyl oleate, isononyl isononanoate, isodecyl oleate, isohexyl decanoate, isononyl octanoate, isopropyl isostearate, isopropyl lanolate, isopropyl laurate, isopropyl myristate, isopropyl palmitate, isopropyl stearate, isostearyl behenate, isosteary citrate, isostearyl erucate, isostearyl glycolate, isostearyl isononanoate, isostearyl isostearate, isostearyl lactate, isostearyl linoleate, isostearyl linolenate, isostearyl malate, isostearyl neopentanoate, isostearyl palmitate, isosteary salicylate, isosteary tartarate, isotridecyl isononanoate, isotridecyl isononanoate, lauryl lactate, myristyl lactate, myristyl myristate, myristyl neopentanoate, myristyl propionate, octyldodecyl myristate, neopentylglycol dicaprate, octyl dodecanol, octyl stearate, octyl palmitate, octyldodecyl behenate, octyldodecyl hydroxystearate, octyldodecyl myristate, octyldodecyl stearoyl stearate, oleyl erucate, oleyl lactate, oleyl oleate, propyl myristate, propylene glycol myristyl ether acetate, propylene glycol dicaprate, propylene glycol dicaprylate, propylene glycol dicaprylate, maleated soybean oil, stearyl caprate, stearyl heptanoate, stearyl propionate, tocopheryl acetate, tocopheryl linoleate, glyceryl oleate, tridecyl ethylhexanoate, tridecyl isononanoate and triisocetyl citrate.

[0117] Non-limiting examples of triglycerides and oils of plant origin include alexandria laurel tree oil, avocado oil, apricot stone oil, barley oil, borage seed oil, calendula oil, canelie nut tree oil, canola oil, caprylic/capric triglyceride castor oil, coconut oil, com oil, cotton oil, cottonseed oil, evening primrose oil, flaxseed oil, groundnut oil, hazelnut oil, glycereth triacetate, glycerol triheptanoate, glyceryl trioctanoate, glyceryl triundecanoate, hempseed oil, jojoba oil, lucerne oil, maize germ oil, marrow oil, millet oil, neopentylglycol dicaprylate/dicaprate, olive oil, palm oil, passionflower oil, pentaerythrityl tetrastearate, poppy oil, propylene glycol ricinoleate, rapeseed oil, rye oil, safflower oil, sesame oil, shea butter, soya oil, soybean oil, sweet almond oil, sunflower oil, sysymbrium oil, syzigium aromaticum oil, tea tree oil, walnut oil, wheat germ glycerides and wheat germ oil.

[0118] Non-limiting examples of PPG alkyl ethers include PPG-2 butyl ether, PPG-4 butyl ether, PPG-5 butyl ether, PPG-9 butyl ether, PPG-12 butyl ether, PPG-14 butyl ether, PPG-15 butyl ether, PPG-15 stearyl ether, PPG-16 butyl ether, PPG-17 butyl ether, PPG-18 butyl ether, PPG-20 butyl ether, PPG-22 butyl ether, PPG-24 butyl ether, PPG-26 butyl ether, PPG-30 butyl ether, PPG-33 butyl ether, PPG-40 butyl ether, PPG-52 butyl ether, PPG-53 butyl ether, PPG-10 cetyl ether, PPG-28 cetyl ether, PPG-30 cetyl ether, PPG-50 cetyl ether, PPG-30 isocetyl ether, PPG-4 lauryl ether, PPG-7 lauryl ether, PPG-2 methyl ether, PPG-3 methyl ether, PPG-3 myristyl ether, PPG-4 myristyl ether, PPG-10 oleyl ether, PPG-20 oleyl ether, PPG-23 oleyl ether, PPG-30 oleyl ether, PPG-37 oleyl ether, PPG-40 butyl ether, PPG50 oleyl ether and PPG-11 stearyl ether. Preferred PPG alky ethers according to the present invention include PPG-15 stearyl ether, PPG-2 butyl ether and PPG-9-13 butyl ether.

[0119] Non-limiting examples of oils from animal origin include herring oil, cod-liver oil and salmon oil.

[0120] Non-limiting examples of silicone oils include cyclomethicone, a dimethyl polysiloxane, dimethicone, an epoxy-modified silicone oil, a fatty acid-modified silicone oil, a fluoro group-modified silicone oil, a methylphenylpolysiloxane, phenyl trimethicone and a polyether group-modified silicone oil.

Viscosity-modifying agent

[0121] A viscosity-modifying agent, in the context of the present invention is an agent which, when added to a hydrophobic oil, facilitates the creation of a hydrophobic breakable vehicle in the form of a breakable oil gel breakable oil foam. The term “breakable” refers to a unique property of the oil gel or the foam wherein said oil gel foam is stable upon dispensing from a container, yet breaks and spreads easily upon application of mild shear force.

[0122] The at least one viscosity-modifying agent is selected from the group consisting of a fatty alcohol, a fatty acid and a wax, wherein said fatty alcohols and/or fatty acids have at least 12 carbon atoms in their carbon backbone.

Fatty alcohols and fatty acids

[0123] Preferably, the fatty alcohol and/or fatty acid and/or wax are solid at ambient temperature. In certain embodiments, the fatty alcohol and/or the fatty acid and/or the wax or the mixture of them have a melting point of more than about 40°C.

[0124] In an embodiment of the present invention, the fatty alcohol is selected from the group consisting of lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol, tetracosanol, hexacosanol, octacosanol, triacontanol, tetratriacontanol. In an embodiment of the present invention, the fatty acid is selected from the group consisting of dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, eicosanoic acid, docosanoic acid, tetracosanoic acid, hexacosanoic acid, heptacosanoic acid, octacosanoic acid, triacontanoic acid, dotriacontanoic acid, tritriacontanoic acid, tetratriacontanoic acid and pentatriacontanoic acid.

[0125] In certain embodiments, the carbon chain of said fatty alcohol or said fatty acid is substituted with a hydroxyl group; and in an additional embodiment said fatty acid is 12hydroxy stearic acid.

Waxes

[0126] Waxes that can be used as part of the viscosity-modifying agent include plant waxes, such as carnauba wax, candelilla wax, ouricury wax, sugarcane wax, retamo wax and jojoba oil; animal waxes, such as beeswax; petroleum derived waxes, including paraffin waxes which are mixtures of saturated of n- and isoalkanes, naphthenes, and alkyl- and naphthene-substituted aromatic compounds; and polyethylene and related derivatives.

[0127] In an embodiment the wax is selected from the group consisting of vegetable wax, beeswax, Chinese wax, cotton wax, bayberry wax, candelilla wax, carnauba wax, castor wax, cuban palm wax, esparto wax, fir wax, flax wax, flower wax, fat wax, japan wax, sandy wax, lanolin wax, ouricury wax, palm waxes, rice bran wax, rice-oil wax, shellac wax, soy wax, sugar cane wax, ucuhuba wax, a hydrogenated oil, hydrogenated castor oil, hydrogenated cottonseed oil, or hydrogenated jojoba oil, mink wax, montan wax, ozokerite, PEG-6 beeswax, rezo wax, spent grain wax, stearyl dimethicone, a paraffin wax, paraffin 58-62°C wax, paraffin 51-53°C wax, paraffin 42-44°C wax, synthetic mineral wax, fischer-tropsch wax, duroxon wax, or polymekon wax, synthetic waxes, albacer wax, atlasene wax, BASF waxes, cardis waxes, ceramid, glyco waxes, flexo wax, or oxazoline waxes, as well as other waxes, as described in “The Complete Technology Book on Wax and Polishes, Publisher: Asia Pacific Business Press Inc., 2006”

Mixtures of fatty alcohols, fatty acids and waxes

[0128] It is to be understood that at least one viscosity-modifying agent is required, but that combinations of more than one viscosity-modifying agent are contemplated. In certain embodiments, a combination of two viscosity-modifying agents is preferred. In certain embodiments, the viscosity-modifying agent combination contains at least one fatty alcohol and at least one fatty acid; or at least one fatty alcohol and least one wax; or at least one fatty acid and at least one wax; or at least one fatty alcohol, at least one fatty acid and least one wax.

[0129] In one or more embodiments the range of ratio of fatty alcohol to fatty acid; or fatty alcohol to wax is about 100:1 to about 1:100; or about 90:1 to about 1:45; or about 80:1 to about 1:40; or about 70:1 to about 1:35; or about 60:1 to about 1:30; or about 50:1 to about 1:25; or about 40:1 to about 1:20; or about 30:1 to about 1:15; or about 20:1 to about 1:10; or about 15:1 to about 1:5; or about 10:1 to about 1:1; or any ranges in between such as 1:20 to 20:1, or preferably from 1:10 to 10:1, or 1:4 to 4:1, or 2:3 or 3:2.

[0130] In certain embodiments, the total concentration of viscosity-modifying agents can be about 0.1% to about 40% by weight; or about 0.4% to about 18% by weight; or about 1% to about 12% by weight.

[0131] In certain other embodiments, the composition comprises viscosity-modifying agents from two classes (e.g., at least one fatty alcohol and at least one fatty acid; or at least one fatty alcohol and at least one wax; or at least one fatty acid and at least one wax); and the concentration of each class respectively is within any one of the following ranges (i) between about 0.1% and about 1%, (ii) between about 1% and about 5%, (iii) between about 5% and about 10%, or (iv) between about 10% and about 20%.

Additional active agents

[0132] Since conditions that can be treated with a tetracycline are often associated with additional conditions, such as inflammation and infection by other microorganisms (other than bacteria), a combination of the tetracycline, and an additional active agent, suitable for the treatment of the underlying disorder or another disorder which substantially concurrently occurs in the same patient is useful for simultaneous therapy of the patient's condition.

[0133] Suitable active agents include but are not limited to an active herbal extract, an acaricides, an age spot and keratose removing agent, an allergen, an alpha hydroxyl acid, an analgesic agent, an androgen, an antiacne agent, an antiallergic agent, an antiaging agent, an antibacterial agent, an antibiotic, an antibum agent, an anticancer agent, an antidandruff agent, an antidepressant, an antidermatitis agent, an antiedemic anent, an antifungal agent, an antihistamine, an antihelminth agent, an anti-hyperkeratosis agent, an anti-infective agent, an antiinflammatory agent, an antiirritant, an antilipemic agent, an antimicrobial agent, an antimycotic agent, an antioxidant, an antiparasitic agent, an antiproliferative agent, an antipruritic agent, an antipsoriatic agent, an antirosacea agent, an antiseborrheic agent, an antiseptic agent, an antiswelling agent, an antiviral agent, an anti-wart agent, an anti-wrinkle agent, an antiyeast agents, an astringent, a beta-hydroxy acid, benzoyl peroxide, a topical cardiovascular agent, a chemotherapeutic agent, a corticosteroid, an immunogenic substance, a dicarboxylic acid, a disinfectant, an estrogen, a fungicide, a hair growth regulator, a haptene, a hormone, a hydroxy acid, an immunosuppressant, an immunoregulating agent, an immunomodulator, an immunostimulant, an insecticide, an insect repellent, a keratolytic agent, a lactam, a local anesthetic agent, a lubricating agent, a masking agent, a metals, a metal oxide, a mitocide, a neuropeptide, a non-steroidal anti-inflammatory agent, an oxidizing agent, a pediculicide, a peptide, a pesticide, a protein, a photodynamic therapy

I ______________________ agent, a progesterone, a radical scavenger, a refatting agent, a retinoid, a sanative, a scabicide, a sedative, a self tanning agent, a skin protective agent, a skin whitening agent, a steroid, a steroid hormone, a vasoactive agent, a vasoconstrictor, a vasodilator, a vitamin, a vitamin A, a vitamin A derivative, a vitamin B, a vitamin B derivative, a vitamin C, a vitamin C derivative, a vitamin D, a vitamin D derivative, a vitamin D analog, a vitamin F, a vitamin F derivative, a vitamin K, a vitamin K derivative, a wound healing agent and a wart remover.

Incompatible Excipients and Undesirable Excipients

[0134] In certain embodiments, the composition is free of petrolatum, surface active agents, protic solvents, certain polar aprotic solvents and silicone thickening agents; and in certain embodiments the foamable composition is substantially free of such excipients. In the context herein, the term “substantially-free” relates to a composition that contains a total of less than about 0.4% of petrolatum, surface active agents, protic solvents, certain polar aprotic solvents and silicone thickening agents cumulatively. Preferably, the composition comprises less than about 0.2% by weight of petrolatum, surface active agents, protic solvents, certain polar aprotic solvents and silicone thickening agents cumulatively and more preferably less than about 0.1%.

Surface active agents

[0135] Surfactants have been categorized in to various sub classes depending on there ionic characteristics, namely non-ionic surfactants, anionic, cationic, zwitterionic, amphoteric and amphiphilic surfactants. Surfactants of all kinds are undesirable in accordance with the present invention, as (i) they were found to cause degradation of the tetracycline antibiotic; and (ii) they are generally known to possess irritation potential.

[0136] Non-limiting examples of classes of non-ionic surfactants that are undesirable according to the present invention include: (i) polyoxyethylene sorbitan esters (polysorbates), such as polysorbate 20, polysorbate 40, polysorbate 60 and polysorbate 80; (ii) sorbitan esters, such as Sorbitan monolaurate and sorbitan monooleate; (iii) polyoxyethylene fatty acid esters, such as, PEG-8 Stearate, PEG-20 Stearate, PEG-40 Stearate, PEG-100 Stearate, PEG150 Distearate, PEG-8 laurate, PEG-10 laurate, PEG-12 laurate, PEG-20 laurate, PEG-8 oleate, PEG-9 oleate, PEG-10 oleate, PEG-12 oleate, PEG-15 oleate and PEG-20 oleate; (iv) PEG-fatty acid diesters; (v) polyethylene glycol (PEG) ethers of fatty alcohols; (vi) glycerol esters, such as glyceryl monostearate, glyceryl monolaurate, glyceryl monopalmitate and glyceryl monooleate; (vii) PEG-fatty acid mono- and di-ester mixtures; (viii) polyethylene glycol glycerol fatty acid esters; (ix) propylene glycol fatty acid esters; (x) mono- and diglycerides; (xi) sugar esters (mono-, di- and tri-esters of sucrose with fatty acids) and (xii) polyethylene glycol alkyl phenols.

[0137] In additional embodiments, the term “substantially surfactant-free” relates to a composition wherein the ratio between the viscosity-modifying agent and the surfactant is between 10:1 or 5:1; or between 20:1 and 10:1 or between 100:1 and 20:1.

[0138] In the context of the present invention, while fatty alcohols, fatty acids and certain waxes are amphiphatic, these substances are not effective as stand-alone surfactants in foamable emulsion compositions, because of their very weak emulsifying capacity and further due to their weak foaming capacity on their own. Hence, fatty alcohols, fatty acids and certain waxes, which constitute the viscosity-modifying agent of the present invention, are not undesirable.

Protic solvents

[0139] Protic solvents, such as short chain alcohols, glycols and glycerin are incompatible with tetracyclines and therefore they are undesirable.

Aprotic polar solvents

[0140] We discovered that certain polar aprotic solvents are incompatible with tetracycline antibiotics. Thus, aprotic polar solvents, such as dimethyl sulfoxide (DMSO), dimethylformamide (DMF), acetonitrile, acetone, methyl ethyl ketone, 1,4-Dioxane and tetrahydrofuran (THF), N-methylpyrrolidone, pyridine, piperidine, dimethylformanide, Nmethyl-2-pyrrolidone and l-methyl-2-pyrrolidinone) and azone (l-dodecylazacycloheptan-2one) are undesirable.

Silicone thickening agents

[0141] Silicone thickening agents comprise one or more polysiloxane-derived components. Such polysiloxanes are typically cross-linked and they have rubber-like characteristics, which require their solubilization in an oil, usually a silicone oil. An example of such a silicone thickening agent is ST-Elastomer 10 (Dow Corning), is a mixture of high molecular weight dimethicone crosspolymer (12%), in cyclopentasiloxane (cyclomethicone, silicone solvent). With reference to bioavailability of an active agent in the skin following topical application, it is conceivable that cross co-polymers will create a non permeable film which should block skin penetration and therefore, it is undesirable. Further, in the context of a breakable foam, cyclomethicone is know as a defoamer and therefore it presence in high concentrations in the breakable hydrophobic composition is undesirable.

[0142] In one or more other specific embodiments the drug carrier is formulated substantially free of elastomers. In one or more other specific embodiments the drug carrier is formulated essentially free of elastomers. In one or more other specific embodiments the drug carrier is formulated substantially free of silicones. In one or more other specific embodiments the drug carrier is formulated essentially free of silicones. In one or more other specific embodiments the drug carrier is formulated with less than about 30% silicone, or less than about 25% silicone, or less than about 20% silicone, or less than about 15% silicone, or less than about 10% silicone, or less than about 7.5% silicone, or less than about 5% silicone or less than about 2% silicone; or less than about 1% silicone; or less than about 0.5% silicone.

Petrolatum

[0143] Petrolatum, also termed “Vaseline”, can be disadvantageous, due to its greasy nature. It is known to leave greasy and sticky feeling after application and occasionally stain cloths. Thus, white petrolatum and other semi-solid oils are not a preferred hydrophobic oil according to the present invention. Additionally, compositions containing a substantial amount of semi-solid hydrophobic oils, e.g., white petrolatum, as the main ingredients of the oil phase of the emulsion, will likely exhibit high viscosity and poor flowability and can be inappropriate candidates for a foamable composition. Thus in one or more embodiments semi-solid hydrophobic oils are a subsidiary component in the composition, for example being present at less than about 25%, less than about 20%, less than about 15% , less than about 10%, or less than about 5% by weight of the hydrophobic breakable composition. In other embodiments formulations with more than 50% petrolatum have been made which produce foam of excellent quality, a collapse time of in excess of three minutes.

Skin Penetration

[0144] Surprisingly, despite the fact that said tetracyclines are hydrophobic at neutral pH (especially minocycline), they do not dissolve in the hydrophobic oils, even at a concentration of 0.05%. So, it arises that at any concentration of more than 0.1% the majority of the tetracycline is suspended, rather than dissolved. However, whilst intuitively the bioavailability of the drug in the skin following topical application is expected to be low, substantial amounts of the tetracycline are found in the skin following one application, as ___________________________________________________________. J shown in in-vitro skin penetration tests. The amounts found in the skin following one application of a hydrophobic breakable composition comprising 1% minocycline and 4% minocycline for 24 hours was 9.49 and 43.12 pg/cm2 respectively. The weight of skin at the delivery area is about 100 mg, which implies that the concentration of minocycline in the skin following 24 hours of exposure is about 90 pg/gr of skin for the 1% formulation and about 430 pg/gr for the 4% formulation. According to the literature, the minimum inhibitory concentration (MIC) for minocycline is less than 4 pg/mL, and therefore, it can be concluded that the concentrations found in the skin are sufficient, or even higher than required to treat bacterial skin infections.

[0145] Even more surprisingly, whilst the tetracycline penetrates well into the skin, the tetracycline does not permeate through the skin. This is a very important feature of the composition of the present invention, as it minimizes the probability of systemic side effects, when topical application is carried out. In one or more embodiments there is no or negligible transdermal delivery. In one or more embodiments the ratio of intradermal to transdermal delivery is about or more than 100:1.

[0146] This means that the current hydrophobic vehicle of minocycline is unique in targeting the delivery of the drug intra-dermally, rather than transdermally.

[0147] In an embodiment, the concentration of the tetracycline in the hydrophobic breakable composition, when tested in the Franz-cell in vitro model, using human or pig’s skin is higher than the lowest intradermal concentration of the tetracycline that is required to kill skin bacteria, such as staphylococcus and streptococcus strains.

[0148] Thus, in an embodiment, the composition, wherein, when tested in the Franz-cell in vitro model using human or pig’s skin, affords an amount of the tetracycline in the skin which is higher than the respective amount transferred transdermally. In certain embodiments, when tested in the Franz-cell in vitro model using human or pig’s skin, the ratio between the amount of the tetracycline in the skin and the respective amount transferred transdermally is higher than about 100; or between 100 and 10; or between 10 and 2; or more than 1.

Anti-microbial effect

[0149] In an in-vitro study, it was revealed that the hydrophobic breakable composition comprising 1% minocycline and 4% minocycline inhibited the growth of streptococcus pyogenes, pseudomonas aeruginosa, staphylococcus aureus, as well as a methicillin-resistant strain of staphylococcus aureus (MRSA). The formulation was also effective against propionbacterium acnes, the causative microorganism in acne.

[0150] This result was unexpected, as the minocycline was primarily suspended in the composition, thus minimizing its expected availability for the antibacterial effect.

Anti-inflammatory and anti-apoptosis effect of the composition comprising a tetracycline

[0151] This effect of minocycline, when treated after the induction of inflammation is surprising, as the literature teaches that “pre-treatment, but not post-treatment, with minocycline markedly attenuated increased pro-inflammatory cytokines release and oxidative and nitrosative stress in mononeuropathic rats.” (see for example, Padi SS, Kulkarni SK, “Minocycline prevents the development of neuropathic pain, but not acute pain: possible antiinflammatory and antioxidant mechanisms”, Eur J Pharmacol. 2008;601:79-87). By contrast, when minocycline was included in the hydrophobic breakable composition of the present invention and applied to skin specimens after induction of UV damage, it significantly decreased apoptosis, as measured by caspase 3 activity; and to elevate skin cell viability.

[0152] In an embodiment, the concentration of the tetracycline is determined by its ability to inhibit the occurrence of apoptosis; or by its ability to decrease caspase 3 activity or by its ability to decrease the occurrence of pro-inflammatory cytokines in an ex-vivo human skin model.

Fields of Applications

[0153] The hydrophobic breakable tetracycline gel and foam compositions of the present disclosure are suitable for treating any inflicted surface. In one or more embodiments, foamable carrier is suitable for administration to the skin, a body surface, a body cavity or mucosal surface, e.g., the cavity and/or the mucosa of the nose, mouth, eye, respiratory system, vagina, urethra or rectum and the ear canal (severally and interchangeably termed herein target site).

[0154] Many conditions can be contemplated based on the antimicrobial properties of the tetracyclines, plus the anti-inflammatory, anti-oxidative and neuroprotective effects of certain tetracycline compound (such as minocycline and doxycycline).

[0155] By selecting a suitable tetracycline compound, or a combination of a tetracycline with at least one additional active agent, the composition of the present disclosure is useful in treating an animal or a human patient having any one of a variety of dermatological disorders, including, but not limited to the list, provided here in an alphabetical manner: abscess, acne, acne conglobata, acne fulminans, acne vulgaris, acne scars, acute febrile neutrophilic dermatosis, acute lymphangitis, allergic contact dermatitis, alopecia, athlete's foot, atopic dermatitis, bacterial skin infections, baldness, basal cell carcinoma, blisters, bromhidrosis, bullous pemphigoid, bum, calluses candidiasis, carbuncles, cellulitis, chemical bums, chicken pox, cholesteatoma, cholinergic urticaria, chronic effects of sunlight, cold sores, cold urticaria, comedones, coms, creeping eruption, cutaneous abscess, cutaneous larva migrans, cutaneous myiasis, dark spots, delusional parasitosis, Dercum disease, dermatitis, dermatitis herpetiformis, dermatological pain, dermatological inflammation, dermographism, dermatophytoses, drug eruptions and reactions, dyshidrotic eczema, ectodermal dysplasia, eczema, ecthyma, epidermoid cyst, epidermal necrolysis, erysipelas, erysipelas, erythrasma, exfoliative dermatitis, erythema multiforme, erythema nodosum, folliculitis, fungal nail infections, fungal skin infections, furuncles, gangrene, genital herpes, granuloma annulare, head lice, hidradenitis suppurativa, hives, folliculitis, hirsutism, hyperhidrosis, hypohidrosis, ichthyosis, impetigo, inflammatory acne, ingrown nails, intertrigo, irritant contact dermatitis, ischemic necrosis, itching, jock itch, Kaposi's sarcoma, keratosis pilaris, lichen simplex chronicus, lichen planus, lichen sclerosus, lymphadenitis, lymphadenitis, lymphangitis, malignant melanoma, mastocytosis, measles, melanoma, melanoma, miliaria, moles, molluscum contagiosum, MRSA, necrotizing subcutaneous infection, necrotizing fasciitis, necrotizing myositis, nodular papulopustular acne, non-inflammatory acne, nummular dermatitis, oral herpes, panniculitis, parapsoriasis paronychia, parasitic skin infections, pemphigus, photo-allergy, photo-damage, photo-irritation, photosensitivity, papules, pediculosis, perioral dermatitis, pimples, pityriasis rosea, pityriasis Lichenoides, pityriasis rosea, pityriasis rubra pilaris, poison ivy, post-operative or post-surgical skin conditions, pressure ulcers, pressure urticaria, pruritis, pseudofolliculitis barbae, psoriasis, PUPPP, purpura, pustules, pyogenic granuloma, rash, ringworm, rosacea, roseola, rubella, scabies, scalded skin syndrome, scarring, scleroderma, sebaceous cyst, seborrheic dermatitis, seborrheic keratosis, shingles, skin aging, skin cancer, skin neoplasia, skin neoplasms, skin rash, skin ulcers, squamous cell carcinoma, staphylococcal scalded skin syndrome, stasis dermatitis, Stevens-Johnson syndrome, sunburn, sun spots, thermal bums, tinea corporis, tinea cruris, tinea pedis, tinea versicolor, toxic epidermal necrolysis, trauma or injury to the skin, varicella zoster virus, vitamin D deficiency, viral skin infections, vitiligo, warts, water hives, wrinkles, xerosis, yeast skin infections and zoster.

[0156] Likewise, the gel or foam composition of the present disclosure are suitable for treating a disorder of a body cavity or mucosal surface, e.g., the surface and/or mucosa of the nose, mouth, eye, ear, respiratory system, vagina, urethra, or rectum. Non limiting examples of such conditions include chlamydia infection, gonorrhea infection, hepatitis B, herpes, HIV/AIDS, human papillomavirus (HPV), genital warts, bacterial vaginosis, candidiasis, chancroid, granuloma Inguinale, lymphogranloma venereum, mucopurulent cervicitis (MPC), molluscum contagiosum, nongonococcal urethritis (NGU), trichomoniasis, vulvar disorders, vulvodynia, vulvar pain, yeast infection, vulvar dystrophy, vulvar intraepithelial neoplasia (VIN), contact dermatitis, pelvic inflammation, endometritis, salpingitis, oophoritis, genital cancer, cancer of the cervix, cancer of the vulva, cancer of the vagina, vaginal dryness, dyspareunia, anal and rectal disease, anal abscess/fistula, anal cancer, anal fissure, anal warts, Crohn's disease, hemorrhoids, anal itch, pruritus ani, fecal incontinence, constipation, polyps of the colon and rectum.

[0157] In one or more embodiments, the hydrophobic breakable gel is specifically useful for ophthalmic administration. Unlike customary ophthalmic ointments, which create a greasy film on the eye and blur the vision, the gel liquefies upon first eye blink and will spread on the eye surface.

[0158] Eye conditions that can be contemplated based on the antimicrobial properties of the tetracycline, plus the anti-inflammatory, anti-oxidative and neuroprotective effects of certain tetracycline compound (such as minocycline and doxycycline) can be categorized, in a non limiting fashion by their symptoms as follows: eye redness, eye pain or light sensitivity, blurred vision, loss of vision, visual disturbances - floaters, flashing, distortion, halos, etc., itching / burning, tearing I discharge, sensation of something in the eye, eyelid problems, double vision.

[0159] Examples of relevant conditions include macular degeneration, age-related macular degeneration, dry macular degeneration and wet macular degeneration, which are associated with photodamage and apoptosis, cataract, which is associated with apoptosis, glaucoma, open-angle glaucoma, closed-angle glaucoma (associated with optical nerve death and apoptosis), retinopathy, proliferative diabetic retinopathy (apoptosis), macular Edema (inflammation), conjunctivitis, uveitis and trachoma (infection).

[0160] Non-limiting examples of ophthalmic conditions that can be treated by a hydrophobic breakable tetracycline composition of the present invention; or such conditions whose complications can be treated by said composition; are provided herewith in their alphabetical order: allergy, blepharitis, cataract, central serous chorioretinopathy, color vision problems, comeal abrasion, corneal edema, corneal ulcer, conjunctivitis, contact lens complications, dacryocystitis, blurred distance vision, dry eye, eale's disease, episcleritis, eyelid ectropion, eyelid entropion, eyelid cellulitis, eye strain, focusing spasm, glaucoma, acute glaucoma, iritis, keratoconus, lyme disease, macular degeneration, macular edema, macular hole, eye medication toxicity, myasthenia gravis, ocular cicatricial pemphigoid, ophthalmic migraine, presbyopia, obstructed tear duct, optic neuritis, optic nerve stroke, orbital fracture, orbital cellulitis, phlyctenulosis, pterygium, recurrent corneal erosion, retinal artery occlusion, retinal detachment, retinal tear, retinal vein occlusion, sarcoidosis, scleritis, sinus disease, strabismus (ocular misalignment), subconjunctival hemorrhage, temporal arteritis, thyroid eye disease, trichiasis, eyelid tumor, twitching of eyelid (eyelid myokymia), uveitis, vitreous detachment and vitreous hemorrhage.

[0161] In light of the hygroscopic nature of the composition, it is further suitable for the treatment and prevention of post-surgical adhesions. Adhesions are scars that form abnormal connections between tissue surfaces. Post-surgical adhesion formation is a natural consequence of surgery, resulting when tissue repairs itself following incision, cauterization, suturing, or other means of trauma. When comprising appropriate protective agents, the foam is suitable for the treatment or prevention of post surgical adhesions. The use of foam is particularly advantageous because foam can expand in the body cavity and penetrate into hidden areas that cannot be reached by any other alternative means of administration.

[0162] In one or more embodiments, there is provided a composition for use in preventing or ameliorating or treating photodamage or radiation damage or photoaging or reducing oxidative stress or inflammation in skin pathologies which are known to be accompanied by apoptic cell death or any two or more thereof.

[0163] In one or more embodiments, there is provided a composition for use in preventing or ameliorating or treating a disorder, the tetracyline composition having at least one property or activity selected from a list including regenerative, anti-apoptotic, antiinflammatory, anti-photodamaging anti-radiation damage and anti-photoaging.

[0164] In one or more embodiments, there is provided a composition comprising a tetracycline for use in preventing protecting from or ameliorating or treating UVB-induced skin damage.

[0165] In one or more embodiments, there is provided a composition comprising a tetracycline for use in preventing, protecting from or ameliorating or treating a disorder with symptoms including increased apoptosis and or decreased cell viability, where the formulation acts to decrease apoptosis and or increase cell viability. In one or more embodiments there is provided a composition for use in decreasing apoptosis and or increasing cell viability.

[0166] In one or more embodiments, there is provided a composition comprising a tetracycline for use in preventing or ameliorating or treating disorders by reducing oxidative stress and inflammation in skin pathologies which are known to be accompanied by apoptotic cell death including rosacea and impetigo.

[0167] In one or more embodiments there is provided a tetracycline composition having regenerative, or anti-apoptotic, or anti-inflammatory, or anti-photodamaging, or antiphotoaging activity, or protective and or therapeutic properties in the case of UVB-induced skin damage, or which decreases apoptosis and or increases cell viability, or in reducing oxidative stress and inflammation in skin pathologies accompanied by apoptotic cell death including rosacea and impetigo, or antibacterial activity, or any two or more thereof.

Cosmetic use

[0168] In one or more embodiments, the composition may be used for cosmetic use. For example it may be used as part of a cosmetic formulation to prevent a cosmetic disorder or to improve the skin.

Administration

[0169] The compositions disclosed herein can be applied to the target site as a gel or a foam. Application can be hourly, 2 hourly, 3 hourly, four hourly, six hourly or eight hourly, twelve hourly, daily, alternate-day or intermittent, as necessary. For reasons of compliance less frequent applications, where possible are preferable such as twice -daily or daily single applications. In cases where prolonged or long term treatment is required a higher initial dose is provided followed by a gradual reduction to a lower maintenance dose, which can be increased if further outbreaks occur.

EXAMPLES

[0170] The invention is described with reference to the following examples, in a nonlimiting manner. The following examples exemplify the foamable compositions and methods described herein. The examples are for the purposes of illustration only and are not intended to be limiting. Many variations will suggest themselves and are within the full intended scope.

Materials

[0171] Exemplary possible ingredients suitable for the production of foamable compositions disclosed herein. Equivalent materials from other manufacturers can also be used satisfactorily.

<td> Chemical Name</td><td> Function</td><td> Commercial Name</td><td> Supplier</td>

<td> Beeswax white</td><td> Foam adjuvant</td><td> Beeswax white</td><td> Henry Lamotte</td>

<td> Behenyl alcohol</td><td> Foam adjuvant</td><td> Lanette 22</td><td> Cognis</td>

<td> Cetostearyl alcohol</td><td> Foam adjuvant</td><td> Speziol Cl6-C18</td><td> Cognis</td>

<td> Cetyl alcohol</td><td> Foam adjuvant</td><td> Speziol C16</td><td> Cognis</td>

<td> Coconut oil</td><td> Solvent</td><td> Coconut oil</td><td> Henry Lamotte</td>

<td> Cyclomethicone-5</td><td> Solvent</td><td> ST-cyclomethicone-5</td><td> Dow</td>

<td> Heavy Mineral Oil</td><td> Solvent</td><td> Paraffin oil liquid heavy</td><td> Gadot</td>

<td> Hydrogenated castor oil</td><td> Foam adjuvant</td><td> Cutina HR</td><td> Cognis</td>

<td> Isostearic acid</td><td> Foam adjuvant</td><td> Isostearic acid</td><td> Stearinerie Dubois</td>

<td> Lanolin</td><td> Foam adjuvant</td><td> Lanolin</td><td> Spectrum</td>

<td> Light Mineral Oil</td><td> Solvent</td><td> Pioner 2076P</td><td> Hansen &amp; Rosenthal</td>

<td> MCT Oil</td><td> Solvent</td><td> Captex 355</td><td> Abitec</td>

<td> Minocycline HC1</td><td> Active agent</td><td> Minocycline HC1</td><td> Hovione</td>

<td> Myristyl alcohol</td><td> Foam adjuvant</td><td> Speziol C14</td><td> Cognis</td>

<td> Octyldodec anol</td><td> Solvent</td><td> Eutanol G</td><td> Cognis</td>

<td> Paraffin wax 51-53</td><td> Wax</td><td> Paraffin 51-53</td><td> Merck</td>

<td> PPG 15 stearyl ether</td><td> Solvent</td><td> Arlamol E</td><td> Uniqema</td>

<td> Propane/Isobutane/Butane (20:78:2)</td><td> Propellant</td><td> A-46</td><td> Aeropres</td>

<td> Propane/Isobutane/Butane (55:18:27)</td><td> Propellant</td><td> AP-70</td><td> Aeropres</td>

<td> Silicon dioxide</td><td> Dispersant</td><td> Aerosil R 972 PH</td><td> Evonik-Goldschmidt GmbH</td>

<td> Soybean oil</td><td> Solvent</td><td> Soybean oil</td><td> Spectrum</td>

<td> Stearic acid</td><td> Foam adjuvant</td><td> Edenol ST IM</td><td> Cognis</td>

<td> Stearyl Alcohol</td><td> Foam adjuvant</td><td> Speziol Cl8</td><td> Cognis</td>

PART A - Gel Formulations

Example 1 - General manufacturing procedures for a gel

[0172] The following procedures are used to produce gel samples described in the examples below, in which only the steps relevant to each formulation are performed depending on the type and nature of ingredients used.

[0173] Step 1: Hydrophobic oil are heated to 60-70°C.

[0174] Step 2: Fatty alcohols if present, fatty acids if present, wax if present, are added to the hydrophobic oil and the formulation is mixed until complete melting.

[0175] Step 3: The formulation is cooled down to 30-40°C, the tetracycline antibiotic is added and the formulation is mixed until homogeneity is obtained.

[0176] Step 4: The formulation is cooled down to room temperature under mixing and packaged into suitable containers.

[0177] By way of non-limiting example, tests are briefly set out below as would be appreciated by a person of the art.

[0178] Viscosity is measured with Brookfield LVDV-II + PRO with spindle SC4-25 at ambient temperature and 20, 10, 5 and 1 RPM. Viscosity is usually measured at 10RPM. However, at the apparent upper limit for the spindle of about 50,000CP, the viscosity at 1RPM may be measured, although the figures are of a higher magnitude.

[0179] Chemical Stability: the amount of the tetracycline antibiotic is analyzed chromatographically. Analysis is carried out after formulation preparation and at appropriate time intervals thereafter. The samples are typically stored in controlled temperature incubators at one or more of 5°C, 25°C and 40°C for several weeks or months. At appropriate time intervals samples are removed from the incubators and the concentration of active agent is measured.

Example 2 - Gel formulations with low viscosity

[0180] The different hydrophobic oils suitable for use in topical pharmaceutical compositions are generally liquid oils have a low viscosity. When these oils are used as-is for active agents topical delivery, they have inter alia two non desirable properties: (1) because of their low viscosity, they tend to drop and to be runny and therefore not easy for the patient to apply onto the skin, (2) they have poor suspending properties leading to the rapid sedimentation of non-dissolved active ingredients (APIs), as described in Table 2.

Table 2 - Low viscosity oleaginous preparations

<td> Formulations</td><td> 001P</td><td> 001</td><td> 002P</td><td> 002</td>

<td> Ingredients</td><td> %w/w</td><td> %w/w</td><td> %w/w</td><td> %w/w</td>

<td> Heavy mineral oil</td><td> 75.00</td><td> 75.00</td><td> -</td><td> -</td>

<td> Light mineral oil</td><td> 25.00</td><td> 25.00</td><td> -</td><td> -</td>

<td> Soybean oil</td><td> -</td><td> -</td><td> 100</td><td> 100</td>

<td> Total</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td>

<td> Minocycline HC1</td><td> -</td><td> 0.1</td><td> -</td><td> 0.1</td>

<td colspan="5"></td>

<td colspan="5"> Results</td>

<td> Viscosity at lOrpm (cP)</td><td> 96</td><td> 92</td><td> 47</td><td> 49</td>

[0181] As shown in formulations 001P and 002P, mixtures of mineral oils and soybean oil have a low viscosity. Formulations 001 and 002, show that after the addition of Minocycline HC1, the viscosity of the formulation remains unchanged and that the active ingredient sediments.

Example 3 - Mineral oil-based formulations with improved viscosity

[0182] The influence of the combination of a tetracycline with fatty alcohols, fatty acids and waxes on formulation viscosity was assessed, as described in Table 3a. Formulations containing a mixture of mineral oils with fatty alcohols, fatty acids or waxes were prepared, and their viscosity was measured before and after the addition of a tetracycline, namely minocycline HCL Table 3a below presents the results of formulation viscosity before and after the addition of a tetracycline, as well as the percentage of viscosity increase due to the addition of the active ingredient.

Table 3a - Combination of a tetracycline with fatty alcohols, fatty acid and waxes

<td> Formulations</td><td> 003</td><td> 004</td><td> 005</td><td> 005B</td>

<td> Ingredients</td><td> %w/w</td><td> %w/w</td><td> %w/w</td><td> %w/w</td>

<td> Heavy mineral oil</td><td> 65</td><td> 65</td><td> 65</td><td> 65</td>

<td> Light mineral oil</td><td> 25</td><td> 25</td><td> 25</td><td> 30</td>

<td> Stearyl alcohol</td><td> 10</td><td> -</td><td> -</td><td> -</td>

<td> Stearic acid</td><td> -</td><td> 10</td><td> -</td><td> -</td>

<td> Beeswax</td><td> -</td><td> -</td><td> 10</td><td> -</td>

<td> Hydrogenated Castor oil</td><td> -</td><td> -</td><td> -</td><td> 5</td>

<td> Total</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td>

Results

<td colspan="5"> Viscosity Results at 10 rpm (cP)</td>

<td> Without Minocycline HC1</td><td> 951</td><td> 1858</td><td> 942</td><td> 848</td>

<td> With 0.1% Minocycline HC1</td><td> 2652</td><td> 8142</td><td> 1695</td><td> 6223</td>

<td> % Viscosity Increase</td><td> +179%</td><td> +338%</td><td> +80%</td><td> +634%</td>

[0183] Very surprisingly, it was discovered that the addition of minocycline HC1 to mineral oil-based formulations 003 to 005B led to a very substantial increase in viscosity, despite the very low amount of minocycline HCL used, namely 0.1%. This totally unexpected results show that the combination of a tetracycline, even at very low concentrations, with fatty alcohols, fatty acids or waxes has a strong synergistic effect on oleaginous formulation viscosity.

[0184] The influence of the addition of different concentrations of a tetracycline on a mineral oils-based formulation was then studied when the active ingredient is combined with a mixture of mineral oils, fatty alcohols, fatty acids and waxes, as described in Table 3b and 3c.

Table 3b - Oleaginous preparations

<td> Formulations</td><td> 238P</td>

<td> Ingredients</td><td> %w/w</td>

<td> Heavy mineral oil</td><td> 59.25</td>

<td> Light mineral oil</td><td> 25.00</td>

<td> Cyclomethicone</td><td> 5.00</td>

<td> Stearyl alcohol</td><td> 1.50</td>

<td> Beeswax</td><td> 2.00</td>

<td> Stearic acid</td><td> 2.00</td>

<td> Hydrogenated castor oil</td><td> 1.50</td>

<td> Behenyl alcohol</td><td> 1.00</td>

<td> Cetostearyl alcohol</td><td> 2.50</td>

<td> Silicon dioxide</td><td> 0.25</td>

<td> Total</td><td> 100.00</td>

<td> Minocycline HC1</td><td> -</td>

<td colspan="2"></td>

<td colspan="2"> Results</td>

<td> Viscosity Results at 10 rpm (cP)</td><td> 6639</td>

% Viscosity Increase

Table 3c - Oleaginous preparations

<td> Formulations</td><td> 238P</td><td> 238A</td><td> 238B</td><td> 238C</td><td> 238D</td>

<td> Ingredients</td><td> %w/w</td><td> %w/w</td><td> %w/w</td><td> %w/w</td><td> %w/w</td>

<td> Formulation 238P</td><td> 100.00</td><td> 99.90</td><td> 99.80</td><td> 99.50</td><td> 99.00</td>

<td> Minocycline HC1</td><td> -</td><td> 0.10</td><td> 0.20</td><td> 0.50</td><td> 1.00</td>

<td colspan="6"></td>

<td colspan="6"> Results</td>

<td> Viscosity Results at 10 rpm (cP)</td><td> 6639</td><td> 15789</td><td> 18476</td><td> 20876</td><td> 20748</td>

<td> % Viscosity Increase</td><td> -</td><td> +138%</td><td> +178%</td><td> +214%</td><td> +213%</td>

[0185] The combination of a tetracycline with a mixture of mineral oils, fatty alcohols, fatty acids and waxes has a strong synergistic effect and increases the formulation viscosity. The viscosity of a formulation containing 0.50% minocycline HC1 is about three times higher than the viscosity of the placebo formulation. The effect on the formulation viscosity is directly related to the concentration of the tetracycline: the higher the tetracycline concentration, the higher the viscosity of the formulation. In formulation 238, it appears that the viscosity increasing effect of minocycline HC1 reaches a plateau when the active ingredient is present at a concentration of about 0.50%.

[0186] In one or more embodiments, there is provided an oleaginous formulation containing mineral oils and a tetracycline in synergistic combination with a fatty alcohol, and/or a fatty acid and/or a wax, wherein the viscosity of the formulation is increased by the addition of the active ingredient by more than about 50%, more than about 100%, more than about 200%, more than about 300%, more than about 500%.

[0187] In one or more embodiments, there is provided an oleaginous formulation containing hydrophobic oils, an active ingredient in synergistic combination with a solidifying agent, wherein the viscosity of the formulation is increased by the addition of the active ingredient by more than about 50%, more than about 100%, more than about 200%, more than about 300%, more than about 500%.

[0188] In one or more embodiments, there increase in the formulation viscosity is related to the concentration of the active agent.

[0189] In one or more embodiments, the viscosity of the formulation is directly proportional to the concentration of the active agent: the higher the concentration of the active ingredient, the higher the formulation viscosity.

[0190] In one or more embodiments, the viscosity increasing effect of the active ingredient reaches a plateau when the concentration of the active ingredient is increased. [0191] In one or more embodiments, the viscosity of the formulation containing the active ingredient is twice the viscosity of the sample formulation when the active ingredient is present at a concentration of less than about 10%, less than about 5%, less than about 1%, less than about 0.5%, less than about 0.1%, less than about 0.05%, less than about 0.01%.

Example 4 - Vegetable oils-based formulations with improved viscosity

[0192] Formulation with different vegetable oils, such as soybean oil and coconut oil were prepared as described in Table 4a, to study the influence of the combination of a tetracycline with a fatty alcohol on formulation viscosity.

Table 4a - Formulation based on vegetable oils

<td> Formulations</td><td> 006</td><td> 007</td>

<td> Ingredients</td><td> %w/w</td><td> %w/w</td>

<td> Soybean oil</td><td> 90</td><td> -</td>

<td> Coconut oil</td><td> -</td><td> 90</td>

<td> Stearyl alcohol</td><td> 10</td><td> 10</td>

<td> Total</td><td> 100.00</td><td> 100.00</td>

<td> Minocycline HC1</td><td> -</td><td> 1.15</td>

<td colspan="3"></td>

<td colspan="3"> Results</td>

<td colspan="3"> Viscosity Results at 10 rpm (cP)</td>

<td> Without Minocycline HC1</td><td> 2771</td><td> 24571</td>

<td> With 0.1% Minocycline HC1</td><td> 1826</td><td> 22459</td>

<td> % Viscosity Increase</td><td>%</td><td>%</td>

[0193] In contrast with the phenomenon observed with mineral oil-based formulations, no increase in the viscosity was observed with the vegetable oils-based formulation when a tetracycline is combined with a fatty alcohol.

[0194] The influence of the addition of a tetracycline on vegetable oils-based formulations was then studied when the active ingredient is combined with a mixture of vegetable oils, fatty alcohols, fatty acids and waxes, as described in Table 4b.

Table 4b - Formulation based on vegetable oils with improved viscosity

<td> Formulations</td><td> 244P</td><td> 244B</td><td> 244A</td>

<td> Ingredients</td><td> %w/w</td><td> %w/w</td><td> %w/w</td>

<td> Soybean oil</td><td> 50.00</td><td> 50.00</td><td> 50.00</td>

<td> Coconut oil</td><td> 23.60</td><td> 23.60</td><td> 23.60</td>

<td> Light Mineral oil</td><td> 5.55</td><td> 4.40</td><td> 0.95</td>

<td> Cyclomethicone</td><td> 5.00</td><td> 5.00</td><td> 5.00</td>

<td> Cetostearyl alcohol</td><td> 3.50</td><td> 3.50</td><td> 3.50</td>

<td> Stearic acid</td><td> 3.00</td><td> 3.00</td><td> 3.00</td>

<td> Myristyl alcohol</td><td> 2.50</td><td> 2.50</td><td> 2.50</td>

<td> Hydrogenated castor oil</td><td> 2.00</td><td> 2.00</td><td> 2.00</td>

<td> Beeswax</td><td> 2.00</td><td> 2.00</td><td> 2.00</td>

<td> Stearyl alcohol</td><td> 1.50</td><td> 1.50</td><td> 1.50</td>

<td> Behenyl alcohol</td><td> 1.10</td><td> 1.10</td><td> 1.10</td>

<td> Silicon dioxide</td><td> 0.25</td><td> 0.25</td><td> 0.25</td>

<td> Total</td><td> 100.00</td><td> 100.00</td><td> 100.00</td>

<td> Minocycline HC1</td><td> -</td><td> 1.15</td><td> 4.60</td>

<td colspan="4"></td>

<td colspan="4"> Results</td>

<td> Viscosity Results at 10 rpm (cP)</td><td> 7214</td><td> 14429</td><td> 17084</td>

<td> % Viscosity Increase</td><td> -</td><td> +100%</td><td> +137%</td>

[0195] As shown in Table 4b, unexpectedly, the combination of a tetracycline with a mixture of hydrophobic oils, fatty alcohols, fatty acids and waxes has a strong synergistic thickening effect and increases the formulation viscosity. The viscosity of a formulation containing 1.15% Minocycline HC1 was about twice higher than the viscosity of the placebo formulation. Moreover, the effect on the formulation viscosity was directly related to the concentration of the tetracycline: the higher the tetracycline concentration, the higher the viscosity of the formulation.

[0196] Thus, in one or more embodiments, there is provided an oleaginous formulation containing vegetable oils and a tetracycline in synergistic combination with a fatty alcohol, a fatty acid and a wax, wherein the viscosity of the formulation is increased by the addition of the active ingredient by more than about 50%, more than about 100%, more than about 200%, more than about 300%, more than about 500%.

[0197] In another experiment, a sample of formulation 244B gel was stored during 6 months at 40°C and tested for minocycline content uniformity. It was found that minocycline was homogeneously dispersed in the formulation, and remained so even after prolonged incubation at 40°C. Additionally, the assay of minocycline in the formulation did not change after 6 months of storage at 40°C. Thus, in one or more embodiments, there is provided a hydrophobic gel formulation wherein the tetracycline is homogeneously dispersed the gel and remains homogeneously dispersed and stable after 6 months of incubation at 40°C.

PART B - Foam Formulations

Example 5 - General manufacturing procedures for a foam

[0198] The following procedures are used to produce the foam samples described in the examples below, in which only the steps relevant to each formulation are performed depending on the type and nature of ingredients used.

Step 1: Hydrophobic oils such as mineral oils are mixed at room temperature. Others solvents such as silicones, if present, are added at room temperature under mixing until formulation homogeneity is obtained.

Step 2: The formulation is warmed to 70-80°C and solid compounds such as fatty alcohols, fatty acids and waxes are added and mixed until complete dissolution.

Step 3: The formulation is cooled down to 30-40°C and active agents are added under mixing until formulation homogeneity is obtained.

Step 4: The formulation is packaged in aerosol canisters which are crimped with a valve, pressurized with propellant and equipped with an actuator suitable for foam dispensing. Optionally a metered dosage unit can utilized, to achieved delivery of desirable and/or repeatable measured doses of foam.

Step 5: Pressurizing is carried out using a hydrocarbon gas or gas mixture. Canisters are filled and then warmed for 30 seconds in a warm bath at 50°C and well shaken immediately thereafter.

Tests

[0199] By way of non-limiting examples certain tests to characterize the foam and its stability are briefly set out below.

Collapse Time

[0200] Collapse Time, which is the measure of thermal stability, is examined by dispensing a given quantity of foam and photographing sequentially its appearance with time during incubation at 36°C. The collapse time result is defined as the time when the foam height reaches 50% of its initial height or if the foam has not yet reached 50% of its initial height after say 180 seconds then the collapse time is recorded as being >180. By way of illustration one foam may remain at 100% of its initial height for three minutes, a second foam may reach 90% of its initial height after three minutes, a third foam may reach 70% of its initial height after three minutes, and a fourth foam may reach 51% of its initial height after three minutes, nevertheless in each of these four cases the collapse time is recorded as >180 seconds since for practical purposes for easy application by a patient to a target the majority of the foam remains intact for more than 180 seconds. If the foam for example reaches 50% of its original height after say 100 seconds it would be recorded as having a collapse time of 100 seconds. It is useful for evaluating foam products, which maintain structural stability at skin temperature for at least 1 minute. Foams which are structurally stable on the skin for at least one minute are termed “short term stable” carriers or foams.

Density

[0201] The foam product is dispensed into preweighed tubes of a known volume and weight. Replicate measurements of the mass of foam filling the tube are made and the density is calculated.

Viscosity

[0202] Viscosity is measured with Brookfield LVDV-II + PRO with spindle SC4-25 at ambient temperature and 10, 5 and 1 RPM. Viscosity is usually measured at 10RPM.

However, at about the apparent upper limit for the spindle of ~>50,000cPs, the viscosity at 1RPM may be measured, although the figures are of a higher magnitude. Unless otherwise stated viscosity of the pre-foam formulation (PFF) is provided. It is not practical to try and measure the viscosity of the foamable formulation with regular propellants since they have to be stored in sealed pressurized canisters or bottles. In order to simulate the viscosity in the foamable formulations with propellant an equivalent weight of pentane (a low volatile hydrocarbon) is added to and mixed with the pre-foam formulation and left overnight. The viscosity is then measured as above.

Chemical Stability

[0203] The amount of active agent present is analyzed chromatographically in foam released from various pressurized canisters. Analysis is carried out at baseline and at appropriate time intervals thereafter. The canisters are typically stored in controlled temperature incubators at one or more of 5°C, 25°C and 40°C. At appropriate time intervals canisters are removed and the amount of active agent in the foam sample is measured.

Bubble Size

[0204] Foams are made of gas bubbles entrapped in liquid. The bubble size and distribution reflects in the visual texture and smoothness of the foam. Foam bubbles size is determined by dispensing a foam sample on a glass slide, taking a picture of the foam surface with a digital camera equipped with a macro lens. The diameter of about 30 bubbles is measured relatively to calibration standard template. Statistical parameters such as mean bubble diameter, standard deviation and quartiles are then determined. Measuring diameter may also be undertaken with image analysis software. The camera used was a Nikon D40X Camera (resolution 10MP) equipped with Sigma Macro Lens (ref: APO MACRO 150mm F2.8 EX DG HSM). Pictures obtained are cropped to keep a squared region of 400 pixels x 400 pixels.

Microscopic observation

[0205] The light microscope enables observing and measuring particles from few millimeters down to one micron. Light microscope is limited by the visible light wavelength and therefore is useful to measuring size of particles above 800 nanometers and practically from 1 micron (1,000 nanometers).

Shakability

[0206] Shakability represents the degree to which the user is able to feel / hear the presence of the liquid contents when the filled pressurized canister is shaken. Shaking is with normal mild force without vigorous shaking or excessive force. When the user cannot sense the motion of the contents during shaking the product may be considered to be non-shakable. This property may be of particular importance in cases where shaking is required for affecting proper dispersion of the contents.

Table of Shakability scoring

<td> Good shakability (conforms to required quality specification)</td><td> 2</td>

<td> Moderate shakability (conforms to required quality specification)</td><td> 1</td>

<td> Not shakable (fails to meet required quality specification) but may still be flowable and allow foam formation of quality</td><td> 0</td>

<td> Is substantially not able to pass through valve</td><td> Block</td>

Centrifugation

[0207] The centrifugation used in this procedure serves as a stress condition simulating the aging of the liquid formulation under investigation. Under these conditions, the centrifugal force applied facilitates coalescence of dispersed globules or sedimentation of dispersed solids, resulting in loss of the desired properties of the formulation.

[0208] Centrifugation can also be executed at a higher rpm for a shorter period or a lower rpm for a longer period bearing in mind the G-force experienced by the formulations is many fold greater than the one G to which a formulation would be exposed to during its shelflife. Centrifugation can also be executed at a higher rpm for the same period, say 3000 or 10,000 rpm to simulate an extremely high stress level.

Example 6 - Surfactant - free hydrophobic foam formulations

[0209] Surface active agents are known to be useful foaming agents, and thus it is not obvious to produce good quality foams free of surfactants. As shown table 6 below, formulations 00IF and 002F containing a mixture of heavy mineral oil and light mineral oil with or without cyclomethicone fail to produce foams and release only liquids from the pressurized canisters. Compounds other than customary surfactants have been identified below that are suitable for the foaming of oleaginous vehicles.

Table 6 - Oleaginous compositions

<td> Formulations</td><td> 001F</td><td> 002F</td>

<td> Ingredients</td><td> %w/w</td><td> %w/w</td>

<td> Heavy mineral oil</td><td> 75.00</td><td> 70.00</td>

<td> Light mineral oil</td><td> 25.00</td><td> 25.00</td>

<td> Cyclomethicone</td><td> -</td><td> 5.00</td>

<td> Total</td><td> 100.00</td><td> 100.00</td>

<td> Propellant A46</td><td> 12.00</td><td> 12.00</td>

<td></td><td></td><td></td>

<td> Results</td><td></td><td></td>

<td> Foam quality</td><td> Poor</td><td> Poor</td>

[0210] Silicone oils such as cyclomethicone are included in the formulations primarily as cosmetic agent, for their contribution to skin feeling properties. Volatile cyclomethicones can help reduce the greasy skin feeling that may be present in oleaginous formulations.

Example &amp;#1512; - Surfactant free foams containing either fatty acid or fatty alcohol

[0211] Two fatty acids were used in combination with heavy mineral oil, light mineral oil and cyclomethicone, and tested for their foaming properties. As described in Table 7a below, formulation 003F containing isostearic acid (a liquid fatty acid) did not give rise to foam but merely generated bubbly liquids. Formulation 004F containing stearic acid (a solid fatty acid) initially produced a fairly good quality foam, but which was not stable and collapsed after 10 seconds. Likewise, compositions containing fatty alcohols produced fairly good quality foams that quickly collapsed (Table 7b). It follows that that fatty acids alone or fatty alcohols alone are not sufficient to stabilize a hydrophobic foam in the absence of a surfactant, even in reasonably high concentrations.

Table 7a - Compositions containing a fatty acid

<td> Formulations</td><td> 003F</td><td> 004F</td>

<td> Ingredients</td><td> %w/w</td><td> %w/w</td>

<td> Heavy mineral oil</td><td> 60.00</td><td> 60.00</td>

<td> Light mineral oil</td><td> 25.00</td><td> 25.00</td>

<td> Cyclomethicone</td><td> 5.00</td><td> 5.00</td>

<td> Stearic acid (Cl 8)</td><td> -</td><td> 10.00</td>

<td> Isostearic acid (Cl8)</td><td> 10.00</td><td> -</td>

<td> Total</td><td> 100.00</td><td> 100.00</td>

<td> Propellant A46</td><td> 12.00</td><td> 12.00</td>

<td></td><td></td><td></td>

<td> Results</td><td></td><td></td>

<td> Foam quality</td><td> Fair</td><td> Fairly Good</td>

<td> Collapse Time (sec)</td><td> 10</td><td> 10</td>

<td> Foam density (/mL)</td><td> -</td><td> 0.071</td>

PFF Viscosity (cP) 58 1442

Table 7b - Compositions containing fatty alcohols

<td> Formulations</td><td> 005</td><td> 006</td><td> 007</td><td> 009</td>

<td> Ingredients</td><td> %w/w</td><td> %w/w</td><td> %w/w</td><td> %w/w</td>

<td> Heavy mineral oil</td><td> 60.00</td><td> 60.00</td><td> 60.00</td><td> 60.00</td>

<td> Light mineral oil</td><td> 25.00</td><td> 25.00</td><td> 25.00</td><td> 25.00</td>

<td> Cyclomethicone</td><td> 5.00</td><td> 5.00</td><td> 5.00</td><td> 5.00</td>

<td> Myristyl alcohol (Cl4)</td><td> 10.00</td><td> -</td><td> -</td><td> -</td>

<td> Cetyl alcohol (Cl6)</td><td> -</td><td> 10.00</td><td> -</td><td> -</td>

<td> Stearyl alcohol (Cl8)</td><td> -</td><td> -</td><td> 10.00</td><td> -</td>

<td> Behenyl alcohol (C22)</td><td> -</td><td> -</td><td> -</td><td> 10.00</td>

<td> Total</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td>

<td> Propellant A46</td><td> 12.00</td><td> 12.00</td><td> 12.00</td><td> 12.00</td>

<td></td><td></td><td></td><td></td><td></td>

<td> Results</td><td></td><td></td><td></td><td></td>

<td> Foam quality</td><td> Fair</td><td> Fair</td><td> Fair</td><td> Fairly Good</td>

<td> Collapse Time (sec)</td><td> 10</td><td> 10</td><td> 10</td><td> 10</td>

<td> Foam density (/mL)</td><td> -</td><td> -</td><td> -</td><td> 0.160</td>

<td> PFF Viscosity (cP)</td><td> 206</td><td> 938</td><td> 585</td><td> 3839</td>

Example 8 - Surfactant free hydrophobic foam formulations containing a combination of Fatty Acids and Fatty Alcohols

[0212] Formulations were prepared, containing a combination of fatty acids and fatty alcohols and checked for their foaming properties. As described in Table 8 below, formulations 010 (containing stearic acid and myristyl alcohol) and formulation 017 (containing isostearic acid and stearyl alcohol) did not give rise to quality foams but merely generated bubbly liquids.

[0213] However, surprisingly, the combination of stearic acid with cetyl alcohol, stearyl alcohol, cetostearyl alcohol or behenyl alcohol (without any surfactants) gave rise to good quality foams having a fine bubble structure as shown in formulations 011,012, 013 and 014. Such foams can be successfully produced in the presence or in the absence of silicone oils, as shown in formulation 011 and 016, despite the defoaming effect of silicones. Moreover, formulations 012 and 014 containing a combination of stearic acid with stearyl alcohol or behenyl alcohol give rise to stable foams which did not collapse after 180 sec at 36°C. Thus, it has been discovered that a combination of fatty alcohols and fatty acids has a synergistic effect and possesses effective foaming properties in the case of oleaginous compositions to achieve a thermally stable breakable foam. Interestingly, cetyl and stearyl alcohol achieved the lowest average bubble size, whilst using a combination of the two led to a substantial reduction in viscosity of the pre foam formulation.

Table 8 - Oleaginous compositions containing various Fatty Acids and Fatty Alcohols

<td> Formulation</td><td> 010</td><td> Oil</td><td> 012</td><td> 013</td>

<td> Ingredients</td><td> %w/w</td><td> %w/w</td><td> %w/w</td><td> %w/w</td>

<td> Heavy mineral oil</td><td> 60.00</td><td> 60.00</td><td> 60.00</td><td> 60.00</td>

<td> Light Mineral oil</td><td> 25.00</td><td> 25.00</td><td> 25.00</td><td> 25.00</td>

<td> Cyclomethicone</td><td> 5.00</td><td> 5.00</td><td> 5.00</td><td> 5.00</td>

<td> Myristyl alcohol</td><td> 5.00</td><td> -</td><td> -</td><td> -</td>

<td> Cetyl alcohol</td><td> -</td><td> 5.00</td><td> -</td><td> -</td>

<td> Stearyl alcohol</td><td> -</td><td> -</td><td> 5.00</td><td> -</td>

<td> Cetostearyl alcohol</td><td> -</td><td> -</td><td> -</td><td> 5.00</td>

<td> Behenyl alcohol</td><td> -</td><td> -</td><td> -</td><td> -</td>

<td> Isostearic acid</td><td> -</td><td> -</td><td> -</td><td> -</td>

<td> Stearic acid</td><td> 5.00</td><td> 5.00</td><td> 5.00</td><td> 5.00</td>

<td> Total</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td>

<td> Propellant A46</td><td> 12.00</td><td> 12.00</td><td> 12.00</td><td> 12.00</td>

<td> Propellant AP-70</td><td> -</td><td> -</td><td> -</td><td> -</td>

<td></td><td></td><td></td><td></td><td></td>

<td> Results</td><td></td><td></td><td></td><td></td>

<td> Foam quality</td><td> Fair</td><td> Good</td><td> Good</td><td> Good</td>

<td> Collapse Time (sec)</td><td> 10</td><td> 30</td><td> &gt;180</td><td> 30</td>

<td> Foam density (g/mL)</td><td> -</td><td> 0.142</td><td> 0.157</td><td> 0.210</td>

<td> Bubble size (micrometers)</td><td> -</td><td> 60</td><td> 74</td><td> 137</td>

<td> PFF Viscosity (cP)</td><td> 107</td><td> 22763</td><td> 23866</td><td> 107</td>

Table 8 - Continued

<td> Formulation</td><td> 014</td><td> 015</td><td> 016</td><td> 017</td>

<td> Ingredients</td><td> %w/w</td><td> %w/w</td><td> %w/w</td><td> %w/w</td>

<td> Heavy mineral oil</td><td> 60.00</td><td> 57.00</td><td> 60.00</td><td> 60.00</td>

<td> Light Mineral oil</td><td> 25.00</td><td> 25.00</td><td> 30.00</td><td> 25.00</td>

<td> Cyclomethicone</td><td> 5.00</td><td> 5.00</td><td> -</td><td> 5.00</td>

<td> Myristyl alcohol</td><td> -</td><td> 3.00</td><td> -</td><td> -</td>

<td> Cetyl alcohol</td><td> -</td><td> -</td><td> -</td><td> -</td>

<td> Stearyl alcohol</td><td> -</td><td> 5.00</td><td> 5.00</td><td> 5.00</td>

<td> Cetostearyl alcohol</td><td> -</td><td> -</td><td> -</td><td> -</td>

<td> Behenyl alcohol</td><td> 5.00</td><td> -</td><td> -</td><td> -</td>

<td> Isostearic acid</td><td> -</td><td> -</td><td> -</td><td> 5.00</td>

<td> Stearic acid</td><td> 5.00</td><td> 5.00</td><td> 5.00</td><td> -</td>

<td> Total</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td>

<td> Propellant A46</td><td> 12.00</td><td> -</td><td> 12.00</td><td> 12.00</td>

<td> Propellant AP-70</td><td> -</td><td> 8.00</td><td> -</td><td> -</td>

<td></td><td></td><td></td><td></td><td></td>

<td> Results</td><td></td><td></td><td></td><td></td>

<td> Foam quality</td><td> Good</td><td> Good</td><td> Good</td><td> Fair</td>

<td> Collapse Time (sec)</td><td> &gt;180</td><td> &gt;180</td><td> &gt;180</td><td> 10</td>

<td> Foam density (g/mL)</td><td> 0.139</td><td> 0.082</td><td> 0.100</td><td> -</td>

<td> Bubble size (micrometers)</td><td> 139</td><td> -</td><td> -</td><td> -</td>

<td> PFF Viscosity (cP)</td><td> 5023</td><td> 18987</td><td> -</td><td> -</td>

Example 9 - Surfactant free hydrophobic foam formulations containing fatty alcohols, fatty acids and waxes

[0214] Formulations, containing a combination of fatty acids, fatty alcohols and waxes were prepared and checked for their foaming properties. As noted in Table 9a below, formulations 018 containing fatty alcohols and low amounts of stearic acid did not give rise to quality foams but generated fairly good quality foam that very quickly collapsed.

Surprisingly, the addition of hydrogenated castor oil and beeswax (in formulation 019) both of which are solid waxes at room temperature enhanced the foam quality and good quality foam that was stable at 36°C was obtained. Furthermore, formulations containing waxes feel less greasy upon application on skin. Thus, it has been discovered that waxes, in combination with a fatty alcohol and a fatty acid, are useful in producing a high quality foam without surfactants.

Table 9a - Hydrophobic foam compositions containing waxes

<td> Formulations</td><td> 018</td><td> 019</td>

<td> Ingredients</td><td> %w/w</td><td> %w/w</td>

<td> Heavy mineral oil</td><td> 63.00</td><td> 59.50</td>

<td> Light mineral oil</td><td> 25.00</td><td> 25.00</td>

<td> Cyclomethicone</td><td> 5.00</td><td> 5.00</td>

<td> Hydrogenated castor oil</td><td> -</td><td> 1.50</td>

<td> Beeswax</td><td> -</td><td> 2.00</td>

<td> Cetostearyl alcohol</td><td> 2.50</td><td> 2.50</td>

<td> Stearyl alcohol</td><td> 1.50</td><td> 1.50</td>

<td> Behenyl alcohol</td><td> 1.00</td><td> 1.00</td>

<td> Stearic acid</td><td> 2.00</td><td> 2.00</td>

<td> Total</td><td> 100.00</td><td> 100.00</td>

<td> Propellant A46</td><td> 12.00</td><td> 12.00</td>

<td></td><td></td><td></td>

<td> Results</td><td></td><td></td>

<td> Foam quality</td><td> Fairly Good</td><td> Good</td>

<td> Collapse Time (sec)</td><td> 10</td><td> 120</td>

<td> Foam density (g/mL)</td><td> -</td><td> 0.207</td>

<td> Bubble Size (micrometers)</td><td> 155</td><td> 79</td>

[0215] Additional formulations were prepared, containing waxes alone and in combination with a fatty acid or a fatty alcohol and checked for their foaming properties. As described in Table 9b below, formulations 021, 021b and 022 containing beeswax alone or in combination with hydrogenated castor oil did not give rise to quality foams but merely generated bubbly liquids. Formulations 020 containing hydrogenated castor oil alone generated fairly good quality foam that collapsed after 60 seconds. On the other hand the combination of beeswax, hydrogenated castor oil and fatty alcohol enhanced the foam quality and produced good quality foam that were stable at 36°C for more than 180 seconds, as shown in formulation 023. However, formulations 024 and 024b composed of combinations of beeswax, hydrogenated castor oil and fatty acid only without fatty alcohol generated fairly good foam that quickly collapsed. This shows the importance of the presence of both fatty alcohols and waxes in oleaginous foam compositions. Additionally, wax such as hydrogenated caster oil or beeswax can not only be used in place of a fatty acid but it can be used to facilitate a lower level of fatty acid presence without compromising the foam properties.

Table 9b - Hydrophobic foam compositions containing waxes

<td> Formulations</td><td> 020</td><td> 021</td><td> 021b</td><td> 022</td><td> 023</td><td> 024</td><td> 024b</td>

<td> Ingredients</td><td> %w/w</td><td> %w/w</td><td> %w/w</td><td> %w/w</td><td> %w/w</td><td> %w/w</td><td> %w/w</td>

<td> Heavy mineral oil</td><td> 60.00</td><td> 60.00</td><td> 60.00</td><td> 60.00</td><td> 60.00</td><td> 60.00</td><td> 60.00</td>

<td> Light mineral oil</td><td> 25.00</td><td> 25.00</td><td> 30.00</td><td> 25.00</td><td> 25.00</td><td> 25.00</td><td> 25.00</td>

<td> Cyclomethicone</td><td> 5.00</td><td> 5.00</td><td> -</td><td> 5.00</td><td> 5.00</td><td> 5.00</td><td> 5.00</td>

<td> Hydrogenated castor oil</td><td> 10.00</td><td> -</td><td> -</td><td> 5.00</td><td> 2.50</td><td> 2.50</td><td> 5.00</td>

<td> Beeswax</td><td> -</td><td> 10.00</td><td> 10.00</td><td> 5.00</td><td> 2.50</td><td> 2.50</td><td> 2.50</td>

<td> Steaiyl alcohol</td><td> -</td><td> -</td><td> -</td><td> -</td><td> 5.00</td><td> -</td><td> -</td>

<td> Stearic acid</td><td> -</td><td> -</td><td> -</td><td> -</td><td> -</td><td> 5.00</td><td> 5.00</td>

<td> Total</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td>

<td> Propellant A46</td><td> 12.00</td><td> 12.00</td><td> 12.00</td><td> 12.00</td><td> 12.00</td><td> 12.00</td><td> 12.00</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td> Results</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td> Foam quality</td><td> Fairly Good</td><td> Fair</td><td> Fair</td><td> Fair</td><td> Good</td><td> Fairly Good</td><td> Fairly Good</td>

<td> Collapse Time (sec)</td><td> 10</td><td> 10</td><td> 10</td><td> 10</td><td> &gt;180</td><td> 10</td><td> 10</td>

Example 10- Tetracycline foam formulations containing different hydrophobic oils

[0216] Minocycline foam formulations were prepared containing soybean oil, octyldodecanol, Medium Chain Triglycerides (MCT) oil and coconut oil, which are other examples of hydrophobic oils. Parameters such as foam quality, collapse time and density were evaluated. As described in Table 10, foams of good quality which did not collapse at 36°C were obtained in different compositions containing these hydrophobic oils. Coconut oil, which on its own is a semi solid paste like oil, was used in combination with liquid soybean oil.

Table 10 - Foam formulation containing different hydrophobic oils

<td> Formulations</td><td> 199</td><td> 216</td><td> 232A</td><td> 235</td><td> 238</td><td> 245</td><td> 248</td><td> 251</td><td> 252</td>

<td> Heavy mineral oil</td><td> 55.89</td><td> 58.82</td><td> -</td><td> -</td><td> 58.14</td><td> -</td><td> -</td><td> -</td><td> -</td>

<td> Light Mineral oil</td><td> 25.00</td><td> 25.00</td><td> 25.00</td><td> -</td><td> 25.00</td><td> 4.44</td><td> 3.04</td><td> 4.44</td><td> 5.54</td>

<td> Cyclomethicone</td><td> 5.00</td><td> 5.00</td><td> 5.00</td><td> 5.00</td><td> 5.00</td><td> 5.00</td><td> 5.00</td><td> 5.00</td><td> 5.00</td>

<td> MCT oil</td><td> -</td><td> -</td><td> -</td><td> 48.89</td><td> -</td><td> -</td><td> -</td><td> -</td><td> -</td>

<td> Octyldodecanol</td><td> -</td><td> -</td><td> -</td><td> 12.00</td><td> -</td><td> -</td><td> -</td><td> -</td><td> -</td>

<td> Coconut oil</td><td> -</td><td> -</td><td> 25.00</td><td> -</td><td> -</td><td> 23.60</td><td> 25.00</td><td> 21.60</td><td> 25.00</td>

<td> PPG 15 stearyl ether</td><td> -</td><td> -</td><td> -</td><td> 15.00</td><td> -</td><td> -</td><td> -</td><td> -</td><td> -</td>

<td> Soybean oil</td><td> -</td><td> -</td><td> 28.39</td><td> -</td><td> -</td><td> 50.00</td><td> 50.00</td><td> 50.00</td><td> 50.00</td>

<td> Lanolin</td><td> -</td><td> -</td><td> -</td><td> -</td><td> -</td><td> -</td><td> -</td><td> 2.0</td><td> 2.00</td>

<td> Hydrogenated castor oil</td><td></td><td> 1.50</td><td> 2.00</td><td> 2.00</td><td> 1.50</td><td> 2.00</td><td> 2.00</td><td> 2.00</td><td> 2.00</td>

<td> Beeswax</td><td></td><td> 1.87</td><td> 2.50</td><td> 2.50</td><td> 2.00</td><td> 2.00</td><td> 2.00</td><td> 2.00</td><td> 2.00</td>

<td> Cholesterol</td><td> -</td><td> -</td><td> -</td><td> -</td><td> -</td><td> -</td><td> 2.50</td><td> -</td><td> -</td>

<td> Myristyl alcohol</td><td> 3.00</td><td> -</td><td> -</td><td> -</td><td> -</td><td> 2.50</td><td> -</td><td> 2.50</td><td> -</td>

<td> Cetostearyl alcohol</td><td> -</td><td> 2.50</td><td> -</td><td> 2.50</td><td> 2.50</td><td> 1.50</td><td> 1.50</td><td> 3.50</td><td> 2.50</td>

<td> Stearyl alcohol</td><td> 5.00</td><td> 1.50</td><td> 5.00</td><td> 5.00</td><td> 1.50</td><td> 3.50</td><td> 3.50</td><td> 1.50</td><td> 1.50</td>

<td> Behenyl alcohol</td><td> -</td><td> 0.70</td><td> 1.00</td><td> 1.00</td><td> 1.00</td><td> 1.10</td><td> 1.10</td><td> 1.10</td><td> 1.10</td>

<td> Aerosil (SiO2)</td><td> -</td><td> -</td><td> -</td><td> -</td><td> 0.25</td><td> 0.25</td><td> 0.25</td><td> 0.25</td><td> 0.25</td>

<td> Stearic acid</td><td> 5.00</td><td> 2.00</td><td> 5.00</td><td> 5.00</td><td> 2.00</td><td> 3.00</td><td> 3.00</td><td> 3.00</td><td> 2.00</td>

<td> Minocycline HC1</td><td> 1.11</td><td> 1.11</td><td> 1.11</td><td> 1.11</td><td> 1.11</td><td> 1.11</td><td> 1.11</td><td> 1.11</td><td> 1.11</td>

<td> Total</td><td> 100</td><td> 100</td><td> 100</td><td> 100</td><td> 100</td><td> 100</td><td> 100</td><td> 100</td><td> 100</td>

<td> Propellant A46</td><td> -</td><td> 12.00</td><td> -</td><td> 12.00</td><td> -</td><td> 12.00</td><td> 12.00</td><td> 12.00</td><td> 12.00</td>

<td> Propellant A70</td><td> 8.00</td><td> -</td><td> 8.00</td><td> -</td><td> 8.00</td><td> -</td><td> -</td><td> -</td><td> -</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td> Results</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td> Foam Quality</td><td> G</td><td> E</td><td> E</td><td> G</td><td> E</td><td> E</td><td> E</td><td> G</td><td> G</td>

<td> Collapse Time at 36°C (sec)</td><td> &gt;180</td><td> 160</td><td> &gt;180</td><td> 150</td><td> &gt;180</td><td> 140</td><td> &gt;180</td><td> &gt;180</td><td> &gt;180</td>

<td> Foam Density (g/mL)</td><td> 0.082</td><td> 0.225</td><td> 0.149</td><td> 0.293</td><td> 0.237</td><td> 0.295</td><td> 0.211</td><td> 0.223</td><td> 0.167</td>

[0217] Comments: All the foams were of high quality and had a collapse time at 36°C in excess of 100 seconds, a foam density of less than 0.3g/ml and the formulations were able to withstand 4 freeze and thaw cycles and still generate foam of high quality with a collapse time at 36°C in excess of 100 seconds. The above formulations, without the addition of propellant, are semi-solid gel-like homogeneous compositions where no separation or sedimentation of the ingredients is observed.

Example 11 - Tetracycline foam formulations containing a wax

[0218] The foaming properties of formulations containing mineral oil, a paraffin wax, a propellant and a tetracycline were studied. As shown in Table 11 below, formulations containing minocycline HC1, produced breakable foams of quality having a collapse time of more than 1 minute at 36°C, despite the absence of fatty alcohols and fatty acids.

Table 11 - Tetracycline foam formulations containing a wax

<td> Formulations</td><td> 053D</td>

<td> Ingredients</td><td> %w/w</td>

<td> Heavy mineral oil</td><td> 79.0</td>

<td> Paraffin 51-53</td><td> 20.0</td>

<td> Minocycline HCL</td><td> 1.0</td>

<td> Total</td><td> 100.0</td>

<td> Propellant AP-70</td><td> 8.0</td>

Results

<td> Foam Quality</td><td> Excellent</td>

<td> Shakability</td><td> 2</td>

<td> Collapse Time at 36°C (sec)</td><td> &gt;180</td>

Example 12 - Petrolatum Based Foamable Compositions

[0219] Foam formulations were prepared containing high amounts of Petrolatum, in combination with liquid oils, fatty alcohols and waxes, according to the general manufacturing procedure described in Example 1. As described in Table 12a, quality breakable foams were obtained in different compositions containing Petrolatum. The prefoam formulations were viscous semi-solid. Upon addition of propellant, the formulations were shakable, indicating that the formulation within the aerosol canister is liquid.

Table 12a - Oleaginous Formulations containing Petrolatum

<td> Formulations</td><td> Al</td><td> A2</td><td> A3</td><td> A8</td>

<td> White petrolatum</td><td> 70.00</td><td> 50.00</td><td> 50.00</td><td> 91.00</td>

<td> Grape seed oil</td><td> -</td><td> 15.00</td><td> -</td><td> -</td>

<td> Jojoba oil</td><td> 15.00</td><td> 15.00</td><td> 15.00</td><td> -</td>

<td> Mineral oil</td><td> 5.00</td><td> 9.00</td><td> 10.00</td><td> -</td>

<td> Wheat germ oil</td><td> -</td><td> -</td><td> 15.00</td><td> -</td>

<td> Paraffin wax 51-53</td><td> -</td><td> 2.00</td><td> 5.00</td><td> -</td>

<td> Beeswax</td><td> 1.00</td><td> 1.00</td><td> -</td><td> 1.00</td>

<td> Cetostearyl alcohol</td><td> 4.00</td><td> 4.00</td><td> 4.00</td><td> 4.00</td>

<td> Hydrogenated castor oil</td><td> 3.00</td><td> 2.00</td><td> -</td><td> 3.00</td>

<td> Cyclomethicone 5-NF</td><td> 1.00</td><td> 1.00</td><td> -</td><td> -</td>

<td> Behenyl alcohol</td><td> 1.00</td><td> 1.00</td><td> 1.00</td><td> 1.00</td>

<td> Total</td><td> 100</td><td> 100</td><td> 100</td><td> 100</td>

<td> Propellant A70</td><td> 10.00</td><td> 10.00</td><td> 10.00</td><td> 10.00</td>

<td></td><td></td><td></td><td></td><td></td>

<td> Results</td><td></td><td></td><td></td><td></td>

<td> Foam Quality</td><td> Excellent</td><td> Excellent</td><td> Excellent</td><td> Excellent</td>

<td> Foam Density (g/mL)</td><td> 0.159</td><td> 0.154</td><td> 0.175</td><td> 0.226</td>

<td> Collapse time at 36°C (sec)</td><td> &gt;180</td><td> &gt;180</td><td> &gt;180</td><td> &gt;180</td>

<td> Mean Bubble size (micrometers)</td><td> -</td><td> -</td><td> 150</td><td> -</td>

[0220] In one or more embodiments, there is provided a foamable formulation comprising Petrolatum, optionally a liquid oil, a fatty alcohol and a wax, wherein the formulation generates quality breakable foam.

[0221] Foam formulations were also prepared without waxes, containing high amounts of Petrolatum, in combination with liquid oils and fatty alcohols, according to the general manufacturing procedure described in Example 1. As described in Table 12b, quality breakable foams were obtained in different compositions containing Petrolatum without waxes. The pre-foam formulations were viscous semi-solid. Upon addition of propellant, the formulations were shakable, indicating that the formulation within the aerosol canister is liquid.

Table 12b - Oleaginous Formulations containing Petrolatum

<td> Formulations</td><td> A4</td><td> A5</td><td> A6</td><td> A7</td>

<td> White petrolatum</td><td> 50.00</td><td> 70.00</td><td> 70.00</td><td> 75.00</td>

<td> Wheat germ oil</td><td> -</td><td> 10.00</td><td> -</td><td> -</td>

<td> Jojoba oil</td><td> -</td><td> 5.00</td><td> -</td><td> -</td>

<td> Avocado oil</td><td> 15.00</td><td> -</td><td> -</td><td> -</td>

<td> Coconut oil</td><td> 15.00</td><td> -</td><td> -</td><td> -</td>

<td> Mineral oil</td><td> 10.00</td><td> 3.00</td><td> 20.00</td><td> 20.00</td>

<td> Shea butter</td><td> 5.00</td><td> 5.00</td><td> 5.00</td><td> -</td>

<td> Cetostearyl alcohol</td><td> 4.00</td><td> 4.00</td><td> 4.00</td><td> 4.00</td>

<td> Cyclomethicone 5-NF</td><td> -</td><td> 2.00</td><td> -</td><td> -</td>

<td> Behenyl alcohol</td><td> 1.00</td><td> 1.00</td><td> 1.00</td><td> 1.00</td>

<td> Total</td><td> 100</td><td> 100</td><td> 100</td><td> 100</td>

<td> Propellant A70</td><td> 10.00</td><td> 10.00</td><td> 10.00</td><td> 10.00</td>

<td></td><td></td><td></td><td></td><td></td>

<td> Results</td><td></td><td></td><td></td><td></td>

<td> Foam Quality</td><td> Good</td><td> Excellent</td><td> Excellent</td><td> Excellent</td>

<td> Foam Density (g/tnL)</td><td> 0.200</td><td> 0.197</td><td> 0.140</td><td> 0.175</td>

<td> Collapse time at 36°C (sec)</td><td> 175</td><td> &gt;180</td><td> &gt;180</td><td> &gt;180</td>

[0222] In one or more embodiments, there is provided a foamable formulation comprising Petrolatum, and a fatty alcohol with optionally shea butter, wherein the formulation generates quality breakable foam. In one or more embodiments, there is provided a foamable formulation comprising Petrolatum, optionally a liquid oil, and a fatty alcohol with optionally shea butter, wherein the formulation generates quality breakable foam.

PART C - Additional properties of Tetracycline compositions

Example 13 - Stability of a tetracycline antibiotic in surfactant free hydrophobic formulations

[0223] Tetracycline antibiotics are known to be very unstable active agents that are degraded by a wide range of commonly used pharmaceutical excipients. For example, it has been found that minocycline is degraded in a few days by different hydrophilic solvents (such as water, glycerin, sodium PCA, propylene glycol and polyethylene glycols), by water dispersed polymers (such as xanthan gum, poloxamers, carbomers, methocel, sodium CMC) and by surfactants (such as polysorbates, sorbitan esters, polyoxyalkyl esters and also lanolinbased surfactants). Thus, the achievement of a long term stable foamable formulation of tetracycline antibiotics described herein was a major challenge and required both extensive research and creativity.

[0224] The following example illustrates the physical stability of foams and the chemical stability of minocycline HC1 (“MCH”) in hydrophobic formulations, namely 238 and 244B as described in Tables 13a, 13b(i) and 13b(ii). In an accelerated stability study, samples were stored at 40°C, and the concentrations of minocycline HC1 were determined by HPLC. The stability test results following 2 months, 3 months and 6 months of storage are shown in Tables 13b(i) and 13b(ii).

Table 13a - Composition of foam formulation incubated at 40°C

<td> Formulations</td><td> 238</td><td> 244B</td>

<td> Ingredients</td><td> %w/w</td><td> %w/w</td>

<td> Heavy mineral oil</td><td> 58.14</td><td> -</td>

<td> Light mineral oil</td><td> 25.00</td><td> 4.44</td>

<td> Cy c lomethicone</td><td> 5.00</td><td> 5.00</td>

<td> Coconut oil</td><td> -</td><td> 23.60</td>

<td> Soybean oil</td><td> -</td><td> 50.00</td>

<td> Lanolin</td><td> -</td><td> -</td>

<td> Hydrogenated castor oil</td><td> 1.50</td><td> 2.00</td>

<td> Beeswax</td><td> 2.00</td><td> 2.00</td>

<td> Cetostearyl alcohol</td><td> 2.50</td><td> 3.50</td>

<td> Stearyl alcohol</td><td> 1.50</td><td> 1.50</td>

<td> Behenyl alcohol</td><td> 1.00</td><td> 1.10</td>

<td> Myristyl alcohol</td><td> -</td><td> 2.50</td>

<td> Aerosil (SiO2)</td><td> 0.25</td><td> 0.25</td>

<td> Stearic acid</td><td> 2.00</td><td> 3.00</td>

<td> Minocycline HC1</td><td> 1.11</td><td> 1.11</td>

<td> Total</td><td> 100.00</td><td> 100.00</td>

<td> Propellant A46</td><td> -</td><td> 12.00</td>

<td> Propellant AP-70</td><td> 8.00</td><td> -</td>

<td></td><td></td><td></td>

<td> Results</td><td></td><td></td>

<td> Foam quality</td><td> Excellent</td><td> Excellent</td>

<td> Collapse Time (sec)</td><td> &gt;180</td><td> &gt;180</td>

<td> Foam density (g/mL)</td><td> 0.237</td><td> 0.284</td>

Table 13b(i) - Chemical stability of foam compositions containing minocycline HC1

<td></td><td></td><td colspan="2"> Minocycline content (% of label clai</td><td> m)</td>

<td> Formulation</td><td> TO</td><td> 2 months at 40°C</td><td> 3 months at 40°C</td><td> 6 months at 40°C</td>

<td> 238</td><td> 98.6</td><td> 95.7</td><td> 96.0</td><td> 92.9</td>

<td> 244B</td><td> 98.7</td><td> 97.1</td><td> 93.8</td><td> 90.3</td>

NM= not measured

Table 13b(ii) - Physical stability of foam compositions containing minocycline HC1

<td> Formulation</td><td> Test</td><td> TO</td><td> 2 months at 40°C</td><td> 3 months at 40״C</td><td> 6 months at 40°C</td>

<td rowspan="3"> 238</td><td> Foam Quality</td><td> Excellent</td><td> Good</td><td> Good</td><td> Good</td>

<td> Collapse Time (sec)</td><td> &gt;180</td><td> &gt;180</td><td> 160</td><td> NM</td>

<td> Foam Density (g/mL)</td><td> 0.237</td><td> 0.259</td><td> 0.289</td><td> 0.263</td>

<td rowspan="3"> 244B</td><td> Foam Quality</td><td> Excellent</td><td> Good</td><td> Good</td><td> Good</td>

<td> Collapse Time (sec)</td><td> &gt;180</td><td> &gt;180</td><td> &gt;180</td><td> NM</td>

<td> Foam Density (g/mL)</td><td> 0.284</td><td> 0.256</td><td> NM</td><td> 0.232</td>

NM= not measured

[0225] Surprisingly, and despite the known instability of tetracycline antibiotics, the accelerated stability results of both formulations after storage at 40°C showed minimal degradation of the active agent in the formulations. The formulations disclosed herein thus show an extended accelerated stability for the tetracycline antibiotic and an outstanding physical stability.

[0226] These results further illustrate the difficulty, complexity and unexpected and non obvious achievement of discovering surfactant free and water free formulations that are chemically stable and are also physically stable over short term, medium term and or long term periods. Testing and identifying single substances that are compatible chemically with the active agent is not sufficient. Combining multiple substances, which on their own are compatible can lead to collective incompatibility. The discovery and knowledge of substances are chemically compatible does not presume physical stability of the composition or vice-versa. Running a compatibility study between individual formulation components and the active agents does not ensure nor achieve physical stability. Discovering combinations of ingredients that can lead to a physically stable formulation in the absence of surfactant, is itself unexpected.

Example 14 - Drug comparison of the stability of minocycline in a hydrophobic gel or foam formulation vs. a reference gel, on contact with skin

[0227] The objective of this study was to assess the degradation of minocycline following exposure to skin. Two samples were tested:

a. Hydrophobic minocycline formulation #244, containing 25% light mineral oil, 5% cyclomethicone, 25% coconut oil, 28.5% soybean oil (hydrophobic oils); 2% hydrogenated castor oil, 2.5% beeswax (waxes); 5% stearyl alcohol, 1% behenyl alcohol (fatty alcohols), 5% stearic acid (fatty acid and about 1% micronized minocycline HC1

b. A reference minocycline gel, which comprised, amongst other components, silicone and ST Elastomer 10, which were mixed prior to application with an additional component that included water, ethanol and propylene glycol.

[0228] Samples were applied to freshly retrieved pig’s ear skin and stored on a Petri dish, with exposure to air and light for 6 hours at 35°C; and the concentrations of minocycline HC1 and its 4-epi degradant were monitored by liquid chromatography.

[0229] As shown in Table 14 below, the reference gel exhibited rapid degradation of minocycline. After 6 hours of exposure the minocycline content decreased by 34% and its 4epi degradant content reached 19.4%, showing that the reference gel product fails to deliver the all the antibiotic amount to the skin in its active form.

[0230] By complete contrast, the “244”, surprisingly, and despite the known instability of minocycline, the skin stability results after 6h showed a very minimal degradation of the active agent: with the content of 4-epi degradant only reached 3.3% and no detectable decrease was observed in the amount of minocycline. Therefore, the foam formulation has an active protective effect on the tetracycline antibiotic upon contact with the skin, and prevents its degradation on the target site of treatment over several hours.

[0231] In consequence of these observations, it is contemplated that the hydrophobic breakable composition protects the tetracycline antibiotic from degradation; and therefore it is useful for the treatment of body sites and surfaces which are moist and are exposed top air and/or light, without losing its potency following the application.

[0232] As known in the art of medicine, the duration of the effect of a drug relates directly to its residence in the treatment site in its active form; and therefore, it can be concluded that the current hydrophobic breakable tetracycline composition will provide long62 term treatment and facilitate administration of the drug in lower frequency, in comparison with other forms of the same drug (if available).

Table 14 - Skins stability results of compositions containing minocycline HC1

<td></td><td> Reference Silicone Gel</td><td> 244 Formulation</td>

<td> Initial minocycline skin concentration</td><td> 96.90</td><td> 92.20</td>

<td> Initial 4-epi degradant skin concentration</td><td> 2.60</td><td> 0.80</td>

<td> Minocycline skin concentration after 6h at 35°C</td><td> 64.00</td><td> 93.70</td>

<td> 4-epi degradant skin concentration after 6h at 35°C</td><td> 19.40</td><td> 3.30</td>

Example 15: Safety of the inactive ingredients

[0233] All inactive ingredients used in the breakable hydrophobic tetracycline formulations are intended for topical use and listed in the current FDA Inactive Ingredient Database; and the concentrations used do not exceed the maximum concentrations given in Database. As an example, Table 15 lays out the acute dose effects of the formulation inactive ingredients of formulation 244, indicating that all these ingredients can be generally regarded as safe (GRAS).

Table 15: Acute dose effects of the formulation inactive ingredients of formulation 244

<td> Ingredient</td><td> Toxicity</td>

<td> Cyclomethicone</td><td> Oral LD50 Rat: &gt;24,134 mg/kg</td>

<td> Coconut oil</td><td> NA (edible)</td>

<td> Soybean oil</td><td> IV LD50 Rat: 16.5 g/kg; IV LD50 Mouse: 22.1 g/kg</td>

<td> Hydrogenated castor oil</td><td> Oral LD50 Rat &gt; 10 g/kg</td>

<td> Beeswax</td><td> Oral LD50 Rat: &gt;5,000 mg/kg</td>

<td> Myristyl alcohol</td><td> Oral LD50 Rat: &gt;10,000 mg/kg; Dermal LD50 Rabbit: &gt;8,000 mg/kg</td>

<td> Cetostearyl alcohol</td><td> Oral LD50 Rat: &gt;10,000 mg/kg; Dermal LD50 Rabbit: &gt;8,000 mg/kg</td>

<td> Stearyl alcohol</td><td> Oral LD50 Rat: &gt;10,000 mg/kg; Dermal LD50 Rabbit: &gt;8,000 mg/kg</td>

<td> Behenyl alcohol</td><td> Oral LD50 Rat: 12,800 mg/kg</td>

<td> Aerosil R 972 (modified silica)</td><td> Oral LD50 Brachydanio rerio: &gt;10,000 mg/kg</td>

<td> Stearic acid</td><td> Oral LD50 Rat: LD50 = 4640; Dermal LD50 Rabbit: &gt;5000 mg/kg</td>

Example 16: Eye Irritation Studies - HET CAM

[0234] The potential of compounds to cause irreversible or severe eye irritation or corrosion may be detected by observing adverse changes, which occur in the chorioallantoic membrane (CAM) of the egg after exposure to test chemicals (Luepke, N.P., Kemper, F.H. “The HET-CAM Test: An Alternative to the Draize Eye Test. ” Fd Chem. Toxic. (1986) 24, 495-496). Fertilized hen's eggs are rotated in an incubator for 9 days, after which any defective eggs are discarded. The shell around the air cell is removed and the inner membranes are extracted to reveal the chorionallantoic membrane. Test chemicals are added to the membrane and left in contact for up to 5 minutes. The membrane is examined for vascular damage and the time taken for injury to occur is recorded. Irritancy is scored according to the speed at which damage occurs. To validate the HET-CAM data, positive and negative controls and vehicle control, are tested in parallel to the test item.

[0235] For each test item, mean scores of replicate eggs is determined. Irritation Score (IS) is interpreted as follows:

<td> Irritation Score</td><td> Irritation Classification</td>

<td> 0-0.9</td><td> Non-Irritant</td>

<td> 1-4.9</td><td> Slight Irritant</td>

<td> 5-8.9</td><td> Moderate Irritant</td>

<td> 9-21</td><td> Severe Irritant</td>

[0236] As can be seen in Table 16 using the in vitro irritation HET-CAM, FXFM244 with no dilution, demonstrated no signs of irritation.

Table 16: HET CAM studies of formulation 244 with 1% and 4% minocycline

<td> Treatment</td><td> Irritation Score</td><td> Classification</td>

<td> Negative Control</td><td> 0</td><td> Non irritant</td>

<td> Positive Control</td><td> 17.09</td><td> Severe</td>

<td> Formulation 244B (1%)</td><td> 0</td><td> Non irritant</td>

<td> Formulation 244A (4%)</td><td> 0</td><td> Non irritant</td>

<td> FXFM244 - Placebo</td><td> 0</td><td> Non irritant</td>

[0237] In consequence of these observations, the hydrophobic breakable tetracycline composition is especially suitable for the treatment of ocular conditions, as well as other conditions that afflict sensitive skin and mucosal membrane areas. Notably, the composition does not include any surfactants, which are known to cause irritation of the eye and additional sensitive areas.

[0238] Eye conditions that can be contemplated based on the antimicrobial properties of the tetracycline, plus the anti-inflammatory, anti-oxidative, anti-apoptosis and neuroprotective effects of certain tetracycline compound (such as minocycline and doxycycline) include, in a non limiting fashion can be categorized by their symptoms as follows: eye redness, eye pain or light sensitivity, blurred vision, loss of vision, visual disturbances - floaters, flashing, distortion, halos, etc., itching / burning, tearing / discharge, sensation of something in the eye, eyelid problems, double vision.

[0239] Examples of relevant conditions include macular degeneration, age-related macular degeneration, dry macular degeneration and wet macular degeneration, which are associated with photodamage and apoptosis, cataract, which is associated with apoptosis, glaucoma, open-angle glaucoma, closed-angle glaucoma (associated with optical nerve death and apoptosis), retinopathy, proliferative diabetic retinopathy (apoptosis), macular Edema (inflammation), conjunctivitis, uveitis and trachoma (infection).

[0240] Non-limiting examples of ophthalmic conditions that can be treated by a hydrophobic breakable tetracycline composition of the present invention; or such conditions whose complications can be treated by said composition; are provided herewith in their alphabetical order: allergy, blepharitis, cataract, central serous chorioretinopathy, color vision problems, comeal abrasion, corneal edema, corneal ulcer, conjunctivitis, contact lens complications, dacryocystitis, blurred distance vision, dry eye, eale's disease, episcleritis, eyelid ectropion, eyelid entropion, eyelid cellulitis, eye strain, focusing spasm, glaucoma, acute glaucoma, iritis, keratoconus, lyme disease, macular degeneration, macular edema, macular hole, eye medication toxicity, myasthenia gravis, ocular cicatricial pemphigoid, ophthalmic migraine, presbyopia, obstructed tear duct, optic neuritis, optic nerve stroke, orbital fracture, orbital cellulitis, phlyctenulosis, pterygium, recurrent corneal erosion, retinal artery occlusion, retinal detachment, retinal tear, retinal vein occlusion, sarcoidosis, scleritis, sinus disease, strabismus (ocular misalignment), subconjunctival hemorrhage, temporal arteritis, thyroid eye disease, trichiasis, eyelid tumor, twitching of eyelid (eyelid myokymia), uveitis, vitreous detachment and vitreous hemorrhage.

Example 17: In-vitro demonstration of antibacterial effects of formulation 244

[0241] In an in-vitro study it was revealed that formulation 244 with 1% and 4% minocycline inhibited the growth of Streptococcus pyogenes, Pseudomonas aeruginosa, Staphylococcus aureus, as well as a methicillin-resistant strain of Staphylococcus aureus (MRSA), as shown in Table 11. The formulation is also effective against Propionbacterium acnes, the causative microorganism in acne. A reference antibiotic product, namely Fucidin Ointment (containing 2% fucidic acid) was effective only against the Streptococcus strains.

[0242] Notably, this effect was observed even though the tetracycline antibiotic is suspended, and is not expected to be readily available for migration on the Petri dish as required for excreting its antimicrobial activity.

Table 17: In Vitro Antibacterial Effect: Comparison between formulation 244, Fucidin

Ointment and Placebo - Diameter of inhibition (mm)

<td></td><td> 244 1% Inhibition Diameter*</td><td> 244 4% Inhibition Diameter*</td><td> 244 Inhibition Diameter*</td><td> Fucidin Inhibition Diameter*</td>

<td> Staphylococcus aureus 6538</td><td> 35,39,36 mm</td><td> &gt;40,&gt;40,&gt;40 mm</td><td> 13,21,20 mm</td><td> &gt;40,&gt;40,&gt;40 mm</td>

<td> Pseudomonas aeruginosa 9027</td><td> 35,36,35 mm</td><td> 40,40,40 mm</td><td> 0,0,0 mm</td><td> 11,12,16 mm</td>

<td> Staphylococcus aureus MRSA 43300</td><td> 32,30,21 mm</td><td> &gt;40,&gt;40,&gt;40 mm</td><td> 17,18,20 mm</td><td> 40,40,38 mm</td>

<td> Streptococcus pyogenes 19615</td><td> 45,38,39 mm</td><td> 38,43,40 mm</td><td> 12,15,11 mm</td><td> 10,12,22 mm</td>

<td> Propionbacterium acnes</td><td> 32,30,35 mm</td><td> 32,30,35 mm</td><td> NA</td><td> NA</td>

* 0 = Ineffective; >30 = Very Effective

[0243] In consequence of these observations, it is contemplated that the hydrophobic breakable tetracycline composition of the present invention is useful in the treatment of any condition or disease, which can be treated with a gel or a foam, which includes a bacterial component as one of its etiological factors.

[0244] In consequence of these observations, the hydrophobic breakable tetracycline composition is especially suitable for the treatment of any condition, which involves as a direct etiological factor or as a secondary complication an infection involving a microorganism which is susceptible to treatment with tetracycline.

[0245] Skin conditions that can be contemplated based on the antimicrobial properties of the tetracycline, plus the anti-inflammatory, anti-oxidative and neuroprotective effects of certain tetracycline compound (such as minocycline and doxycycline) include, in a non limiting fashion include, for example: cellulitis, cutaneous abscess, erysipelas, erythrasma, folliculitis, furuncles and carbuncles, hidradenitis suppurativa, impetigo, ecthyma, lymphadenitis, lymphangitis, MRSA infections, necrotizing subcutaneous infection and staphylococcal scalded skin syndrome.

[0246] Likewise, the composition of the present invention is suitable for the treatment of any eye condition that involve bacterial infection, vaginal infections, and any additional infections of target sites that may be treated by a gel or a foam.

[0247] The same compositions can be applicable in any case of a condition which involves a secondary infection, such as atopic dermatitis and other itching and xerotic conditions.

Example 18: Skin delivery and systemic bioavailability of minocycline

[0248] The transdermal penetration of minocycline was tested using the Franz cell invitro diffusion system. This system is commonly used to test the delivery of drugs through the skin from semisolid topical dosage forms. Porcine skin was used according to the OECD Draft New Guideline 428, due to its similar permeation characteristics to human skin. The following experimental parameters were employed:

- Two formulations were tested: 244 1% and 244 4% (comprising 1% and 4% Minocycline respectively).

- Vertical Franz diffusion cells were used (PermeGear, 1.77 cm2 area, 14 ml receptor fluid).

cells were used to test the 4% formulation, 5 cells were used to test the 1% formulation and. One cell was used as a negative control (without any applied sample). Approximately 500mg of product was placed in each cell.

- The receiving compartments were sampled at baseline and 3, 6, 9 and 24 hours following application. At the 24 hours time point the skin was processed as follows:

- Residues of materials were removed from the skin using filter paper, followed by stripping the skin once using adhesive tape Scotch Magic® Tape, 3M.

Sequential 19 tapes (9 and 10) should be transferred into two separate vials with 3 mL extraction solution (“Stratum Comeum 1” and “Stratum Comeum 2”).

The circular skin area (1.77 cm2) was cut and transferred to a 3 mL extraction solution (Viable skin - VS samples) vial.

Table 18: In Vitro Skin Delivery: Formulation 244 (1% and 4%)

<td></td><td colspan="2"> FMFX244 foam 1% (n=5)</td><td colspan="2"> FMFX244 foam 4% (n=6)</td>

<td></td><td> Minocycline qg/cm²</td><td> STD</td><td> Minocycline qg/cm²</td><td> STD</td>

<td> Stratum Comeum 1</td><td> 7.77</td><td> 4.32</td><td> 33.63</td><td> 20.41</td>

<td> Stratum Comeum 2</td><td> 0.93</td><td> 0.77</td><td> 7.49</td><td> 8.67</td>

<td> Total Stratum Comeum</td><td> 8.70</td><td> 4.97</td><td> 41.12</td><td> 16.89</td>

<td> Viable Skin</td><td> 0.79</td><td> 0.19</td><td> 2.00</td><td> 0.81</td>

<td> Total Intradermal Delivery</td><td> 9.49</td><td></td><td> 43.12</td><td> 17.48</td>

<td> Receiving Compartment</td><td> 0.00</td><td></td><td> 0.00</td><td></td>

[0249] The following conclusions can be drawn from this experiment

1. Transdermal delivery: Following 24 hours of exposure the amount which was found in the receptor cells was below the limit of quantitation (LOQ) of the analytical method (LOQ = 2 qg/mL). This result clearly demonstrates no systemic absorption of the drug from the FMFX244 foam formulation. It can therefore be concluded that topical application of

FMFX244 foam should not involve any systemic adverse effects.

2. Intra-dermal delivery (delivery into the skin): The total mean amount of Minocycline in the skin following 24 hours of exposure was 9.5 qg/cm2 for the 1% formulation and 43 ug/cm2 for the 4% formulation. The weight of skin at the delivery area is about 100 mg, which implies that the concentration of Minocycline in the skin following 24 hours of exposure is about 90 ,ug/gr of skin for the 1% formulation and about 430 pg/gr for the 4% formulation. According to the literature, the minimum inhibitory concentration (MIC) for Minocycline is less than 4 qg/mL, and therefore, it can be concluded that the concentrations found in the skin are sufficient to treat bacterial skin infections.

[0250] Notably, this skin penetration profile was observed even though the tetracycline antibiotic is suspended, and is not expected to be readily available for migration into the skin. [0251] In consequence of these observations, the hydrophobic breakable tetracycline composition is especially suitable for the treatment of any skin condition, which occurs in the skin.

[0252] Skin conditions that can be contemplated based on the antimicrobial properties of the tetracycline, plus the anti-inflammatory, anti-oxidative, anti-apoptosis and neuroprotective effects of certain tetracycline compound (such as minocycline and doxycycline) include, in a non limiting fashion include, for example: abscess, acne, acne scars, acute febrile neutrophilic dermatosis, allergic contact dermatitis, alopecia, athlete's foot, atopic dermatitis, basal cell carcinoma, blisters, bromhidrosis, bum, calluses candidiasis, carbuncles, cellulitis, chicken pox, cholinergic urticaria, chronic effects of sunlight, cold sores, cold urticaria, comedones, coms, cutaneous abscess, cutaneous larva migrans, cutaneous myiasis, dark spots, delusional parasitosis, dermatitis, dermographism, dermatophytoses, drug eruptions and reactions, dyshidrotic eczema, ecthyma, epidermoid cyst, erysipelas, erysipelas, erythrasma, exfoliative dermatitis, erythema multiforme erythema nodosum, folliculitis, fungal nail infections, furuncles, genital herpes, granuloma annulare, head lice, hidradenitis suppurativa, hives, folliculitis, hirsutism, hyperhidrosis, hypohidrosis, ichthyosis, impetigo, ingrown nails, intertrigo, irritant contact dermatitis, itching, jock itch, keratosis pilaris, lichen simplex chronicus, lichen planus, lichen sclerosus, lymphadenitis, lymphangitis, mastocytosis, measles, melanoma, miliaria, moles, molluscum contagiosum, MRSA, necrotizing subcutaneous infection, nummular dermatitis, oral herpes, panniculitis, parapsoriasis paronychia, photo-allergy, photo-damage, photo-irritation, photosensitivity, papules, perioral dermatitis, pimples, pityriasis rosea, pityriasis Lichenoides, pityriasis rosea, pityriasis rubra pilaris, poison ivy, pressure ulcers, pressure urticaria, pruritis, pseudo folliculitis barbae, psoriasis, PUPPP, pustules, pyogenic granuloma, rash, ringworm, rosacea, roseola, rubella, scabies, sebaceous cyst, seborrheic dermatitis, seborrheic keratosis, shingles, skin cancer, skin rash, staphylococcal scalded skin syndrome, stasis dermatitis, Stevens-Johnson syndrome, sunburn, tinea corporis, tinea cruris, tinea pedis, tinea versicolor, toxic epidermal necrolysis, varicella zoster virus, vitamin D deficiency, water hives, xerosis, zoster.

Example 19: Ex-vivo studies of the anti-apoptosis effects of formulation 244 with 1% and 4% minocycline

[0253] UVB irradiation of the skin is known to decrease cell viability, total antioxidant capacity, while increasing the levels of inflammation (pro-inflammatory cytokines secretion) and epidermal cell apoptosis.

Pre-treatment with Formulation 244

[0254] Specimens of human skin in organ culture were treated topically with Formulation 244 (placebo, 1% and 4% minocycline) for 24 hours, then irradiated with UVB (400 mJ/cm2) and incubated for additional 72 hours. Apoptosis activation was measured 24 h postirradiation by measuring the extent of caspase 3 activity in epidermal sheets.

[0255] Table 19a and Table 19b demonstrate the effect of formulation 244 (with or without minocycline) on epidermal cell apoptosis and viability following UVB irradiation of the skin organ culture. As shown in Table 19a, apoptosis activation was significantly decreased by FXFM244 in a dose-dependant manner.

[0256] Cell viability, as measured by the MTT assay 72 hours after irradiation was increased, as shown in Table 19b. One set of mediators implicated in apoptosis belong to the asparate-specific cysteinyl proteases or caspases. A member of this family, caspase-3 has been identified as being a key mediator of apoptosis of mammalian cells. In general terms, as caspase activation increases, a higher percentage of cell death will ensue.

Table 19a: Effect of Formulation 244 on apoptosis activation in skin organ culture after UVB irradiation

<td rowspan="2"></td><td colspan="2"> Caspase 3 activity (slope/min)</td>

<td> Non-irradiated</td><td> Irradiated</td>

<td> Carrier</td><td> 24</td><td> 177</td>

<td> 244-l%MCH</td><td> 4</td><td> 100</td>

<td> 244 - 4% MCH</td><td> 3</td><td> 69</td>

Table 19b: Effect of Formulation 244 on skin organ culture viability

<td rowspan="2"></td><td colspan="2"> Viability (RFU 540/590 nm)</td>

<td> Non-irradiated</td><td> Irradiated</td>

<td> Carrier</td><td> 6971.25</td><td> 6207.5</td>

<td> 244-1% MCH</td><td> 7615.25</td><td> 8862.25</td>

<td> 244 - 4% MCH</td><td> 8155.5</td><td> 9015.5</td>

[0257] Comments: It was observed that in the case of cells in contact with a placebo formulation, irradiation causes a decrease in cell viability. On the other hand, in cells in contact with a formulation containing minocycline, higher cell viability was observed both before and after irradiation compared to the placebo, which is a sign of cell regeneration. Therefore, the present formulation comprising minocycline is able to prevent cell death in the case of irradiation and can even stimulate or cause cell regeneration.

Treatment with Formulation 244 after UV damage induction

[0258] Specimens of human skin in organ culture were irradiated with UVB (400 mJ/cm2) and incubated for additional 72 hours. Formulation 244 4% was then applied to the skin and apoptosis activation was measured 24 h post-treatment by measuring the extent of caspase 3 activity in epidermal sheets.

[0259] As shown in Table 19c , Formulation 4% treatment resulted in about 60% decrease in epidermal cell apoptosis.

Table 19c: Therapeutic effect of Formulation 244 (application post irradiation)

<td></td><td> Caspase 3 activity (slope/min)</td>

<td> Control</td><td> 118</td>

<td> 244 - 4% MCH</td><td> 46</td>

Conclusion

[0260] These results demonstrate that Formulation 244 has protective properties in the case of UVB-induced sun damage or any other condition associated with sunlight or other light (e.g., lazer) exposure. It may therefore be able to reduce skin photodamage and photoaging, and more generally to reduce oxidative stress and inflammation in skin pathologies which are known to be accompanied by apoptotic cell death.

[0261] Notably, this skin penetration profile was observed even though the tetracycline antibiotic is suspended, and is not expected to be readily available for migration into the tissue and providing the desirable anti-apoptotic effect.

[0262] In consequence of these observations, the hydrophobic breakable tetracycline composition is especially suitable for the treatment of any condition, which includes apoptosis as one of its etiological factors.

Example 20 - Compatibility Study

[0263] Procedure: Minocycline hydrochloride (“MCH”) was incubated as a suspension with various excipients at 25°C and 40°C for maximum of sixty days or to the point where degradation was suspected. The ratio between MCH and the tested excipient is detailed below. Visual inspection was the major criterion for indication of compatibility. The color of intact MCH suspension is pale yellow; and any change of color (e.g., to dark orange, red, green, brown and black) indicates oxidation or degradation.

[0264] Hydrophilic solvents were tested for compatibility with MCH at a ratio of MCH: excipient of 1:250. dimethyl isosorbide, glycerin, ethanol, propylene glycol, butylene glycol, PEG 200, hexylene glycol, PEG 400, dimethyl sulfoxide and diethylene glycol monoethyl ether were found to be incompatible with MCH.

[0265] Oily emollients and waxes were tested for compatibility with MCH at a ratio of MCH: excipient of 1:250 for Oily emollients and 1:50 for waxes. Hydrogenated castor oil, castor oil, cocoglycerides, disopropyl adipate, mineral oil, coconut oil, beeswax, MCT oil, cyclomethicone, isododecane, cetearyl octanoate, gelled mineral oil, isopropyl myristate, PPG 15 stearyl ether, mineral oil heavy, octyl dodecanol, white petrolatum, petrolatum, paraffin 51-53,, paraffin 58-62, calendula oil, shea butter, grape seed oil, almond oil, jojoba oil, avocado oil, peanut oil, wheat germ oil and hard fat were found to be compatible with MCH. Pomegranate seed oil was found to be incompatible with MCH.

[0266] The compatibility of MCH with hydrophobic surfactant was tested following solubilization of the surfactant in mineral oil (mineral oil was previously shown to be compatible with MCH). Surfactants were tested for compatibility with MCH at a ratio of MCH: excipient of 1:50. PEG150 distearate, laureth 4, PEG 40 hydrogenated castor oil, PEG 75 lanolin, glucam P20 distearate, PEG 100 stearate, glyceryl monostearate, PEG 40 stearate, montanov S (cocoyl alcohol (and) Cl2-20 alkyl glucoside)), alkyl lactate, benton gel, SPAN 60, sorbitan sesquistearate, SPAN 40, SPAN 80, Tween 20, Tween 60,ceteth 2, sucrose stearic acid esters DI813, ceteareth 20, steareth 2/steareth 21, methyl glucose sesquistearate, Oleth 20, and PPG 20 methyl glucose ether were found to be incompatible with MCH.

Sucrose stearic acid esters DI803, sucrose stearic acid esters DI807 and sucrose stearic acid esters DI 811 were found to be compatible with MCH; however, not all of them dissolved in oil (e.g. 1811, 1813).

[0267] Foam adjuvants were tested for compatibility with MCH at a ratio of MCH: excipient of 1:50. Isostearyl alcohol, behenyl alcohol, stearyl alcohol, cetyl alcohol, oleyl alcohol, myristyl alcohol, cetostearyl alcohol, palmitic acid, stearic acid and oleic acid were found to be compatible with MCH, Isostearic acid was not compatible with MCH.

[0268] Additives were tested for compatibility with MCH at a ratio of MCH: excipient of 1:50. Aerosil and Menthol were found to be compatible with MCH. Titanium dioxide and Ethocel were not compatible with MCH.

[0269] Additives were tested for compatibility with MCH. Minimal quantities of water (ΙΟΟμΕ) were added to MCH, suspended in excipients that had demonstrated compatibility to examine whether water can enhance oxidation/degradation in the absence or presence of antioxidant. In parallel, antioxidants were added to the MCH suspensions comprising water. Antioxidants were also added to excipients which were found to be non compatible with MCH. Addition of water caused prompt degradation of MCH. Addition of the antioxidants alpha-tocopherol, BHA/BHT and propyl gallate did not prevent MCH degradation. Compatible excipients became incompatible in the presence of water. Addition of antioxidants did not alter this result.

Example 21 - Color and Pigmentation Study

Part A - Color change

[0270] Samples of formulations 238 and 216 with 1% minocycline were incubated during 3 months at 25°C, 30°C and 40°C. Following this period the foam product was actuated and the change in color was observed. Minimal to no change was observed following 3 months storage at all three temperatures.

Part B - Pigmentation

[0271] A large amount of MCH 244 4% was actuated on human skin to observe whether any skin pigmentation occurs. Minimal to no skin pigmentation following rubbing the foam onto the skin was noticed, when observed after about 30 seconds.