Immediate release pharmaceutical granule compositions and a continuous process for making them

The present invention is in the field of drug delivery systems and immediate 5 release technology. Particularly, the invention is in the field of immediate release pharmaceutical granule compositions. More specifically, the invention relates to such compositions with low to moderate drug loading for immediate release of drugs which have very low solubility in water. The invention also relates to various solid pharmaceutical dosage forms such as sachets, gelules and tablets including such immediate release granule compositions. Finally the invention relates to a continuous process for manufacturing the said immediate release granule compositions.

BACKGROUND OF THE INVENTION

Some general considerations relating to drug formulation are provided herein in order to understand the constraints applicable to the formulation of drugs which have very low solubility in water and at the same time the kind of pharmaceutical solid formulations to which the present invention relates.

Tablets and capsules are generally unsuitable for administering high doses of biologically active ingredients since individual large dosage forms are difficult to swallow or necessitate the administration of several tablets or capsules at a time, leading to impaired patient compliance.

Hard gelatin capsules are known as a conventional pharmaceutical dosage form. Their sizes have been standard since the start of industrial manufacture of drug compositions, ranging from 5 (corresponding to a volume of 0.13 ml) up to 000 (corresponding to a volume of 1.36 ml). Thus, when a large amount of ingredient is required for each dosage unit, depending on the bulk density of the formulation, it may be necessary to use large size capsules which are too large to swallow or, even worse, a size 000 capsule may be too small to receive the said amount.

Pellets and granules have been filled into hard gelatin capsules to be used as conventional or controlled release dosage forms, however the latter are rather difficult to manufacture.

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The concept of tabletting coated active ingredient particles is therefore of major interest. Attempts have been made to produce tablets comprising microcapsules because of the advantages resulting from the microencapsulated substance being protected from external influences and vice-versa, e.g. increased stability, reduced chances of irritations or undesirable reactions with other components in a mixture, ability to mask unpleasant tastes and smells, etc. However, compaction of coated beads or pellets for making tablets encounters many difficulties and problems. As is well known in the pharmaceutical industry, beads or pellets are quite distinguishable from granules. Beads can be defined as io small, free-flowing spherical or sphere-like particulates manufactured by pelletization, i.e. the agglomeration of fine powders or granules of drug substances and excipients using appropriate processing equipment. As opposed to the process of granulation, the production of beads by pelletization results in a larger average size and a narrower size-range distribution.

Another difficult problem is the formulation of drugs having very low watersolubility into solid dosage forms for immediate release. Few solutions to this problem have been disclosed in the art. For instance, U.S. Patent Publication No. 2001/0048946 provides solid dosage forms of sparingly water-soluble pharmaceutical agents, i.e. solid or crystalline drugs having a water-solubility of 10 to 33 pg/ml at 25°C, such as glitazones. More particularly, this document discloses a pharmaceutical composition in the form of a solid particulate dispersion of such a pharmaceutical agent dispersed throughout a matrix of a water-soluble polymer such as polyvinylpyrrolidone, hydroxypropyl cellulose, or hydroxypropyl methylcellulose. In a preferred embodiment, the particulate pharmaceutical agent is dispersed in the water-soluble polymer in a weight ratio of about 10% to about 90% active ingredient to about 90% to about 10% polymer. Other conventional excipients such as glycerin, propyleneglycol, Tween, stearic acid salts and the like can be added.

U.S. Patent Publication No. 2001/0044409 discloses a process for the preparation of a poorly water soluble drug in solid dispersion comprising the steps of (a) blending the drug with a carrier, (b) dissolving a surfactant and a

PI 20030770 plasticizer/solubilizer in water, (c) spraying the surfactant-plasticizer/solubilizer solution onto the drug/carrier mixture in a fluid bed granulator, (d) extruding the resulting granulation through a twin screw extruder with at least one heating zone, and (e) milling the extrudate to a powdery mass of the solid drug dispersion. Within the scope of this process, the said carrier may be selected from the group consisting of polyvinylpyrrolidone, high molecular weight polyethylene glycol, urea, citric acid, vinyl acetate copolymer, acrylic polymers, succinic acid, sugars and mixtures thereof; the said plasticizer/solubilizer may be selected from the group consisting of low molecular weight polyethylene glycol, propylene glycol, glycerin, io triacetin, triethyl citrate, sugar alcohols and mixtures thereof, and the said surfactant may be selected from the group consisting of Tween, Span, Pluronics, polyoxyethylene sorbitol esters, monodiglycerides, polyoxyethylene acid polyoxyethylene alcohol and mixtures thereof. This process suffers from the disadvantage of providing a heating zone in the twin screw extruder and consequently controlling and monitoring the temperature profile of the extruder.

However none of the above processes appear to be successful in formulating solid dosage forms of drugs having very low water-solubility, i.e. a solubility lower than 10 pg/ml, preferably lower than 5 pg/ml. This problem is applicable to a large number of drugs, including those belonging to the family of diaminopyrimidines, such as stated in U.S. Patent No. 6,211,185.

U.S. Patent 3,639,637 discloses oestrogen compositions for the preparation of stable aqueous suspensions that can be sprayed onto animal feed, comprising (by weight) 70-95% of water-dispersible gel-forming microcrystalline cellulose and 5-30% of finely-divided diethylstilbestrol (a compound which is virtually insoluble in water) and optionally further up to one third of the weight of the composition of a hydrocolloid selected from the group consisting of sodium carboxy-methylcellulose, methylcellulose and hydroxyethylcellulose. The two latter cellulose compounds are known, namely from EP-A-403,383, to contribute to an extended linear drug release rate.

EP-A-352,190 discloses a solid pharmaceutical unit with a delayed dissolution of the active ingredient, i.e. allowing retention of the active ingredient

PI 20030770 and avoiding its complete and immediate availability by a simple contact with an aqueous liquid medium. It further discloses in example 9 paracetamol microgranules obtained from a mixture of 182 g paracetamol (a drug belonging to class I of the Biopharmaceutical Classification System and having a water-solubility of 14 mg/ml), 728 g microcrystalline cellulose (AVICEL PH 101) and 90 g sodium carboxymethylcellulose. EP-A-352,190 however does not teach using a cyclodextrin compound as a drug dissolution enhancer.

U.S. Patent 5,362,860 discloses (table VI, example C) a composition with improved storage stability comprising (by weight) 0.05% of a pyridine based oxime io (a drug undergoing hydrolysis into an aldehyde in an acidic environment), 70% cyclodextrin, 3% crosscarmellose (a crosslinked polymer) and 20.95% microcrystalline cellulose.

WO-A-99/12524 solves the problem of drug formulations with both a relatively fast or quick onset of the therapeutic effect and the maintenance of a therapeutically active plasma concentration for a relatively long period of time, by providing an oral modified release multiple-units composition wherein the unit dosage form comprises at least (i) a first fraction being able to release at least 50% of the drug within the first 20 minutes of a certain dissolution method, and (ii) a second fraction for delayed and extended release of the drug. The multiple-units of the first fraction may be granulates or, provided that a surfactant is added to the formulation, coated or uncoated pellets. Formulation of the first fraction depends on the specific drug but typically includes wet-granulation, and an antacid-like or other alkaline substance was found to have a pronounced increasing effect on the release rate.

U.S. Patent 5,646,131 discloses (example 4) rapidly dissolving capsules containing a granulate formulation of a water-insoluble or sparingly soluble drug, such as terfenadine (less than 0.01 mg/ml water-solubility), surfactants (Tween 80 and sodium lauryl sulfate), cyclodextrin, Avicel PH 101 (microcrystalline cellulose) and a disintegrant/swelling agent (Primojel®, i.e. sodium carboxymethyl starch) in a weight ratio of 10:72 to Avicel. These capsules provide better drug absorption, due

Pl 20030770 to the presence of cyclodextrin, as evidenced by the figure showing a 90% drug release within 45 minutes.

Elbers et al. in Drug Development and Industrial Pharmacy (1992) 18(5):501-517 discloses theophylline pellets with a drug loading from 10 to 50% obtained by extrusion-spheronization with AVICEL 581 (a blend of microcrystalline cellulose and sodium carboxymethylcellulose). Theophylline is a drug with a watersolubility of 8 mg/ml (according to Merck Index, 12^th edition 1996) and high permeability (according to FDA Guidance to Industry, 2000), thus belonging to class I of the Biopharmaceutical Classification System.

io U.S. Patent 4,235,892 discloses a series of 1-aryl-2-acylamido-3-fluoro-1propanol antibacterial agents including D-(threo)-1-p-methylsulfonyl phenyl-2dichloroacetamido-3-fluoro-l-propanol, an antibacterial agent known as florfenicol and useful for veterinary purposes. Florfenicol has low solubility in water (about 1.3 mg/ml), as well as in many pharmaceutically acceptable organic solvents such as

1,2-propanediol, glycerin, and benzyl alcohol. For oral administration, these 1-aryl2-acylamido-3-fluoro-1-propanol may be compounded in the form of tablets, or may even be admixed with animal feed. U.S. Patent 4,235,892 therefore discloses making tablets by compressing granules of a composition comprising the said 1aryl-2-acylamido-3-fluoro-1-propanol (in a drug loading range from 8.3% to 41.7% by weight), lactose, microcrystalline cellulose, starch and magnesium stearate.

The Biopharmaceutical Classification System according to G. Amidon et al.

in Pharm. Res. (1995) 12:413-420 provides for two classes of poorly soluble drugs, i.e. Class II and Class IV, and a class of highly soluble drugs, i.e. Class I. According to M. Martinez et al., Applying the Biopharmaceutical Classification System to

Veterinary Pharmaceutical Products (Part I: Biopharmaceutics and Formulation Consideration) in Advanced Drug Delivery Reviews (2002) 54:805-824, a drug substance should be classified as highly soluble when the highest dose strength is soluble in at most 250 ml of aqueous media over the pH range 1-7.5. In view of its water solubility (1.3 mg/ml) and of a maximal dose of 20 mg/kg for pigs, it is easy to calculate that the highest dose strength of florfenicol administered to pigs is soluble in an amount of water which is well above the limit value for the definition of a class

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I highly soluble drug. Furthermore it is known from J. Voorspoels et al. in The

Veterinary Record (October 1999) that florfenicol has a good oral bioavailability, so that it can be classified as a Class II compound as it is not a highly soluble drug and it shows no absorption problems.

There is a specific need in the art to provide a solid formulation of florfenicol, a drug for oral administration to warm-blooded animals, such as cattle with naturally-occurring bovine respiratory disease, swine, sheep, goats and poultry, which at present is only available in the form of injectable solutions. Until now the skilled person has failed in the design of such a solid formulation of florfenicol, which can further be admixed with animal feed if necessary.

SUMMARY OF THE INVENTION

The present invention is based on the unexpected finding that drugs belonging to Class II (poorly soluble, highly permeable) or Class IV (poorly soluble, poorly permeable) of the Biopharmaceutical Classification System, including drugs having very low water-solubility can be successfully formulated into immediate release pharmaceutical dosage forms provided that (1) they are admixed in suitable proportions with a first pharmaceutically acceptable excipient comprising a dextrincontaining compound, or a blend of microcrystalline cellulose and a swellable polymer, or a mixture of the said dextrin-containing compound and the said blend, and with a second pharmaceutically acceptable excipient being a non-aqueous wetting compound comprising at least a solid fraction, and that (2) they are formulated into granule compositions, not pellet compositions. Preferably, these granule formulations are advantageously obtained by a continuous manufacturing process involving a low temperature extruding step in a extruding means. Based on the above teachings, the invention also provides various pharmaceutical dosage forms such as sachets and solid shaped articles such as tablets and hard gelatin capsules including the said granule compositions. The invention also relates to the treatment of bacterial infections, including bovine respiratory disease, in cattle and fish by oral administration to the animal of an effective amount of the abovereferred immediate release pharmaceutical dosage form.

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BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 represents the release, as a function of time, of hydrochlorothiazide from a granule composition according to the invention.

Figure 2 represents the release, as a function of time, of florfenicol from a granule composition according to the invention.

Figure 3 shows a twin screw extruder useful for manufacturing the granule compositions of the present invention.

DETAILED DESCRIPTION OF THE INVENTION io

In a first embodiment, this invention relates to an immediate release pharmaceutical granule composition comprising (i) at least one drug belonging to Class II (poorly soluble, highly permeable) or Class IV (poorly soluble, poorly permeable) of the Biopharmaceutical Classification System, e.g. a drug having very is low water-solubility such as defined herein, wherein the said drug constitutes at least about 0.5% by weight and up to about 20% by weight, preferably from 1 to 15% by weight, of the composition, the said composition further comprising (ii) a first excipient selected from the group consisting of:

- blends of a microcrystalline cellulose and a swellable polymer in respective amounts such that the weight ratio of the said polymer to the microcrystalline cellulose in the blend is above about 2 :100 and up to about 30 :100,

- one or more dextrin-containing compounds selected from the group consisting of maltodextrins, cyclodextrins and derivatives thereof, and

- mixtures of the said dextrin-containing compounds and the said blends, and 25 (iii) a wetting amount of second excipient being a non-aqueous wetting compound or meltable compound and comprising a solid fraction and optionally a liquid fraction.

In a second embodiment, this invention relates to continuous process for manufacturing the aforesaid immediate release pharmaceutical composition, comprising the steps of:

(a) homogenising a mixture comprising the drug (i) belonging to Class II or Class IV of the Biopharmaceutical Classification System, e.g. a drug having

PI 20030770 very low water-solubility, the first excipient (ii) and the solid fraction of the second excipient (iii), (b) feeding the mixture obtained in step (a) and optionally the liquid fraction of the second excipient (iii) into an extruding means having one or more mixing zones and one or more transport zones, and (c) extruding the materials fed in step (b) while operating the extruding means at a temperature not above the melting temperature of the solid fraction of the second excipient until an immediate release pharmaceutical granule composition is obtained.

More detailed ways of implementing the invention will now be described in more details by referring both to the immediate release pharmaceutical granule composition and the process for manufacturing the same. In a preferred embodiment, the first excipient (ii) may be a blend of a microcrystalline cellulose and a swellable polymer and the said swellable polymer may be an uncrosslinked carboxyalkylcellulose metal salt such as for instance sodium or calcium carboxymethylcellulose.

In yet another preferred embodiment of the invention, the first excipient (ii) may be present in the composition in an amount from about 40% to about 85% by weight of the composition.

Microcrystalline cellulose, in particular a pharmaceutical grade thereof, is well known in the art of pharmaceutical industry for its high surface porosity and its outstanding capillary character. It is available from a variety of commercial sources, e.g. Avicel ® PH 101 (commercially available from FMC Corporation, Philadelphia, Pennsylvania), Emcocel ® (Mendell), Vivocel ® (JRS) and the like. Microcrystalline cellulose is a partially purified depolymerized form of cellulose and is obtained by treating pulps derived from fibrous plant material with mineral acid. The acid preferentially attacks the less ordered or amorphous regions of the cellulose polymer chain, thereby exposing and freeing the crystalline sites which form cellulose crystallite aggregates. The reaction mixture is washed to remove the degraded byproducts, the resulting wet-cake is freed of water and the dried cellulose crystallite aggregates, or more commonly microcrystalline cellulose,

PI 20030770 recovered. Microcrystalline cellulose is a white, odourless, tasteless, relatively freeflowing powder, insoluble in water, organic solvents, dilute alkalies and dilute acids.

A swellable polymer suitable for use in the present invention may be defined herein preferably as an ionic hydrocolloid polymer which is easily miscible with microcrystalline cellulose and which, on its own, is able to form a colloidal suspension in an aqueous environment, the colloidal particles e.g. forming a threedimensional network or grid-like structure throughout the liquid phase. Suitable examples of such polymer include pharmaceutical grades of sodium carboxymethylcellulose such as commercially available under the tradenames

Nymcel ®, Tilose ® and Blanose ® (Aqualon). Preferably, the swellable polymer is a low molecular weight and/or low viscosity polymer. For instance when the swellable polymer is an uncrosslinked carboxyalkylcellulose metal salt, it should preferably have sufficient unsubstituted hydroxyl groups in order to hydrogen bond to the microcrystals of the microcrystalline cellulose upon drying and the substituent groups should have ability to impart water-solubility. The degree of substitution of the carboxyalkylcellulose should preferably not exceed about 0.9 and more preferably be within a range of 0.5 to 0.9. Also, the viscosity of a 2% aqueous solution of the swellable polymer at 20°C should preferably be below 1,000 mPa.s, more preferably within a range from about 20 to 800 mPa.s.

The swellable polymer and the microcrystalline cellulose may be afforded separately at the time of making the pharmaceutical granule compositions of the present invention or they may be present in the form of a co-processed blend.

A co-processed blend of the swellable polymer together with microcrystalline cellulose is readily available, e.g. as Avicel ® RC 581 and Avicel ® CL 611 (both commercially available from FMC Corporation), both well known in the art in the form of pharmaceutically acceptable grades. This cellulosic blend may alternatively be prepared by bringing the two blend components into intimate contact under suitable conditions, for instance by subjecting the washed filter cake containing microcrystalline solids from the acid degradation of cellulose to intense attritive forces, thus resulting in a further break up of the cellulose crystallite aggregates and an increase in sub-micron particles. As the attrition proceeds, a sufficient

PI 20030770 amount of the swellable polymer (e.g. sodium carboxymethyl cellulose) is added to the aqueous mixture in order to at least partially coat the individual microcrystals of the microcrystalline cellulose. Upon completion of the attrition, the blend is dried and recovered. The dried product is readily redispersible in aqueous media to give gels. Important for its effectiveness in the present invention is the fact that this blend is a non-disintegrating water-insoluble water-dispersible powder before it is granulated in admixture with the poorly soluble drug and the second excipient. Preferably at least about 1% by weight and more preferably at least about 30% by weight of the powder blend particles have an average size not greater than about io 1.0 pm as determined by electron microscopic examination.

For optimal efficiency, the weight ratio of the said swellable polymer to the microcrystalline cellulose in the immediate release pharmaceutical granule composition of the invention, respectively in the (co-processed) blend as above defined, should be above about 2 :100 and up to about 30 :100, preferably between about 7 :100 and 20 :100.

Drug dissolution enhancing agents such as maltodextrins, cyclodextrins and derivatives thereof, in particular their pharmaceutically acceptable grades, are well known in the art and are available from a variety of commercial sources. They may be collectively referred as starch cyclic degradation products containing 6 to 8 glucose residues, or alternatively as cyclic oligosaccharides composed of L-glucose molecules linked by a or β osidic bonds having a toric form. A suitable representative embodiment of such a cyclodextrin derivative enhancing agent consists of hydroxypropyl-B-cyclodextrin.

Preferably the amount of the first excipient represents from about 40% by weight to about 80% by weight of the immediate release pharmaceutical granule composition of the invention, depending on the amounts of the other excipients (such as fillers) optionally present therein.

According to the invention, the aforesaid immediate release is a release of at least about 50% of the said drug within 30 minutes in water, preferably a release of at least about 70% of the said drug within 10 minutes in water, and more preferably a release of at least about 80% of the said drug within 10 minutes in water,

PI 20030770 preferably under physiological temperature and pH conditions. As shown in the following examples, the present invention is also successfully applicable to drugs having low, but not very low, water-solubility but which are relatively highly dosed drugs (i.e. constitute from about 10% to about 20% of the composition) for therapeutic efficiency, such as florfenicol.

The immediate release pharmaceutical granule compositions of this invention may further comprise one or more pharmaceutically acceptable fillers. The aforesaid pharmaceutically acceptable fillers may be selected for instance from hydrocolloids (such as xanthan gum), binding agents, glidants, lubricants, io surfactants and diluents. The term “pharmaceutically acceptable filler” as used herein is intended to refer to any material which is inert in the sense that it does not have any therapeutic and/or prophylactic effect per se but does not adversely interfere with the therapeutic or prophylactic property of the drug or pharmaceutical active ingredient being formulated. The nature and amount of such fillers are not critical to the present invention. They include for instance binding agents such as starch, gelatin, glucose, alginic acid, sodium and calcium alginates, water-soluble acrylic (co)polymers, polyvinylpyrrolidone, polyaminoacids, ethylene-vinyl acetate copolymers and the like; natural and synthetic mineral fillers or glidants such as fumed (colloidal) silica (e.g. commercially available under the tradename Aerosil ®), magnesium silicates such as talc, diatomaceous earth, aluminium silicate such as kaolinite, montmorillonite or mica, magnesium aluminium silicate such as attapulgite and vermiculite, carbon such as charcoal, sulphur and highly dispersed silicic acid polymers; water-soluble diluents such as lactose, sorbitol and the like.

According to this invention, the drug (i) preferably has a water-solubility below about 2 mg/ml, more preferably below about 5 pg/ml and may even have a watersolubility as low as about 0.2 pg/ml, at room temperature and physiological pH. Non-limiting examples of such drugs include for instance hydrochlorothiazide, nimodipine, flufenamic acid, mefenamic acid, bendroflumethiazide, benzthiazide, ethacrinic acid, nitrendipine, itraconazole, florfenicol and diaminopyrimidines.

Suitable examples of diaminopyrimidines include, without limitation, 2,4-diamino-5(3,4,5-trimethoxybenzyl) pyrimidine (known as trimethoprim), 2,4-diamino-5-(3,4PI 20030770 dimethoxybenzyl) pyrimidine (known as diaveridine), 2,4 diamino-5-(3,4,6trimethoxybenzyl) pyrmidine, 2,4-diamino-5-(2-methyl-4,5-dimethoxybenzyl) pyrimidine (known as ormetoprim), 2,4-diamino-5-(3,4-dimethoxy-5-bromobenzyl) pyrimidine, and 2,4-diamino-5-(4-chloro-phenyl)-6-ethylpyrimidine (known as pyrimethamine). These drugs usually belong to Class II (poorly soluble, highly permeable) or Class IV (poorly soluble, poorly permeable) of the Biopharmaceutical Classification System according to G. Amidon et al. in Pharm. Res. (1995) 12:413420. As will be appreciated by those skilled in the art, these drugs belong to various therapeutic classes, including diuretics, anti-hypertensive agents, anti-viral agents, io antibacterial agents, etc.

According to this invention, the granules of the immediate release pharmaceutical granule composition preferably have a diameter ranging from about 100 and 2,500 pm.

The second excipient (iii) of the immediate release pharmaceutical granule 15 composition may suitably be selected from the group consisting of polyethyleneglycols and polypropyleneglycols having weight number molecular weights between about 300 and about 5,000; glycerol; propyleneglycol and glycerides (such as mono-, di- and triglycerides of polyethyleneglycol fatty acid esters, including those commercially available under the tradename Gelucire®). Suitable examples of the latter include those having both a portion derived from a glyceride and a portion derived from a polyethylene glycol ester. For instance, it is suitable to use polyglycosylated glycerides. The term polyglycosylated glycerides as used herein denotes a mixture of mono-, di- and triglycerides with polyethylene glycol (PEG) mono- and diesters of C₈-Ci₈ fatty acids with a molecular weight preferably between about 200 and about 600, optionally further including glycerol and/or free PEG, the hydrophilic-lipophilic balance (HLB) value of which is controlled by the chain length of the PEG and the melting point of which is controlled by the chain length of the fatty acids, of the PEG and of the degrees of saturation of the fatty chains, and thus of the starting oil. Similarly the expression C₈-Ci₈ fatty acids as used herein denotes mixtures in various proportions of caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid and stearic acid, when these acids are

PI 20030770 saturated, and the corresponding unsaturated acids. As is well known to the skilled person, the proportions of these fatty acids may vary as a function of the starting oils. Examples of the latter include, but are not limited to, saturated polyglycolized Ce-Cw glycerides, such as the PEG-8 caprylate/caprate glyceride esters sold by

Gattefosse Corporation under the tradename Labrasol; PEG-6 caprylic/capric glycerides sold by Huis Aktiengesellschaft under the trade name Softigen 767; PEG-60 corn glycerides sold by Croda under the trade name Crovol M-70; Ceteareth-20 sold by Henkel Corporation under the trade name Emulgin B2; diethyleneglycol monoethyl-ethers sold by Gattefosse Corporation under the trade io name Transcutol; a mixture of C₈-Cie saturated polyglycosylated glycerides having a melting point within a range of about 42-48°C and a HLB within a range of about 8 to 16 such as sold by Gattefosse Corporation under the trade names Gelucire 48/09, Gelucire 44/14 and Gelucire 42/12; and mixtures thereof in various proportions. When a polyethyleneglycol is used for instance, it may comprise a higher molecular weight solid fraction and a lower molecular weight liquid fraction, the latter acting as a plasticizer.

In a preferred embodiment of the invention, the second excipient (iii) may be present in the immediate release granule composition in an amount from about 15% to about 40% by weight of the composition. In yet another preferred embodiment of the invention, the weight ratio between the liquid fraction and the solid fraction of the second excipient (iii) may be from 0:1 (no liquid fraction) to about 1:2, more preferably not more than 1:3. In yet another more preferred embodiment of the invention, for instance when a maltodextrin is used as the first excipient (ii) and a polyethyleneglycol is used as the second excipient (iii), the weight ratio of the first excipient (ii) to the second excipient (iii) is in a range from about 1:1 to about 5:1.

According to this invention, the immediate release pharmaceutical granule composition may optionally further comprise one or more other drugs different from the drug having poor water-solubility, but preferably belonging to the same therapeutic class, in particular when combined drug therapy is desired.

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The process of the present invention is preferably performed in an apparatus, such as a twin screw extruder, comprising a barrel having a granulation chamber provided with inlets for supplying the drug (i), the first excipient (ii) and the solid fraction of the second excipient (iii), and at least one continuously operated rotating transporting means. The said extruder is preferably operated at a temperature not above about 45°C, more preferably at a temperature not above about 35°C, i.e. there is no need to provide a heating zone on the said extruder, therefore no need to provide sophisticated means for controlling and monitoring the temperature of the extruder. The extruder is preferably operated at a rotating speed between about io 5 and 300 rpm, depending upon low shear, medium shear or high shear is desired. The continuously operated rotating transporting means of the extruder comprises one or more mixing zones and one or more transport zones. The configuration and number of these zones may be widely varied, however at least one mixing zone is most preferred, being very advantageous to induce interaction between the various components of the composition to be extruded. The remaining of the screw may then consist of transportation zones. Single or twin lead discharge screws can be used. As is standard in this art, the length to diameter ratio of each rotating transporting means may be within a range from about 15 to about 60.

The present invention also provides solid shaped articles comprising a core consisting of an immediate release pharmaceutical granule composition as defined herein-above. This solid shaped article may be in the form of a tablet or a hard gelatine capsule. Methods for producing tablets, such as compression, or hard gelatine capsules from granule compositions are well known to those skilled in the art. In the case of a tablet, the solid shaped article may further comprise a coating, according to standard practice in the art.

The term solid shaped article as used herein means any article being in a hard solid state at temperatures not exceeding about 60°C and having a definite geometrical shape, such as for instance ordinary tablets, effervescent tablets, pills, lozenges and other compressed dosage forms.

The solid shaped articles of the present invention may further optionally contain additives typically used in the formulation of such articles, for instance

PI 20030770 flavoring agents (such as anethole, benzaldehyde, vanillin, ethyl vanillin, ethyl acetate, methyl salicylate and the like), lubricants (such as magnesium stearate), sweeteners (such as sucrose, mannitol, aspartame, saccharin and its salts), colorants and/or buffering agents.

The present invention further provides a sachet comprising an immediate release pharmaceutical granule composition as above defined.

The invention provides advantages over the existing formulations of poorly soluble drugs. In particular it provides a solid formulation of florfenicol for oral administration, optionally together with animal feed, to warm-blooded animals such io as cattle with naturally-occurring bovine respiratory disease, swine, sheep, goats and poultry. It also provides a solid formulation of trimethoprim, optionally in combination with sulfadiazine (usually in a trimethoprim/sulfadiazine weight ratio of about 1:5), for oral administration to fish as an antibacterial agent effective against both gram-positive and gram-negative bacteria.

The following examples are provided solely for the purpose of illustrating various embodiments of the invention, and without any intention of limiting the scope thereof.

FXAMPLE 1 - twin screw extruder for producing a pharmaceutical granule composition

The twin screw extruder used for performing the following pharmaceutical granule preparations is described in figure 3. It consists of seven distinct zones, wherein zones (1), (2), (4) and (6) are three transport zones, zones (3) and (5) are two mixing zones and zone (7) is a densification zone (which could alternatively be omitted, if desired). The extruder is placed within a granulation chamber provided with inlets for supplying the drug and the various excipients.

FXAMPLES 2 and 3 - pharmaceutical granule formulations including maltodextrin and xanthan gum

The following formiulations were prepared using the extruding equipment of example 1:

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Low water-soluble drug; 100 g

Polyethyleneglycol 400: 52.5 g

Polyethyleneglycol 4000: 187.5 g

Maltodextrin 01982 622.5 g

Xanthan gum: 37.5 g

Maltodextrin 01982 is a neutral taste, medium DE maltodextrin with good dispersibility which complies with European and U.S. Pharmacopeia and which is commercially available from Cerestar (Neuilly-sur-Seine, France). The solid fraction of the formulation consisting of hydrochlorothiazide (example 2), PEG 4000, io maltodextrin and xanthan gum was homogenised in a planetary mixer. This mixture was fed into the twin screw extruder at a rate of 29.9 g/min. The liquid phase (PEG400) was continuously pumped into the twin screw extruder at a rate of 6.9 g/min. The screw speed during the extrusion was 250 rpm. The temperature of the different zones of the twin screw extruder was set at 25°C, yielding experimental extrusion temperatures of 25°C in zone (1), 26°C in zone (2), 26°C in zone (3) and 25°C in zones (4) and (5).

In the case of florfenicol (example 3) being used as the drug instead of hydrochlorothiazide, the same parameters were used and the experimental temperatures measured in zones (1) to (5) were 26°C, 28°C, 28°C, 27°C and 25°C respectively.

The extruded granules were collected, sieved and further analysed for drug dissolution (data shown in figures 1 and 2, formulations B and D). Figure 1 shows that 72% release of hydrochlorothiazide (example 2) is obtained after 10 minutes, and 90% after 25 minutes. Figure 2 shows that 80% release of florfenicol (example

3) is already obtained after 10 minutes, and 100% after 20 minutes.

EXAMPLES 4 and 5 - pharmaceutical granule formulations including microcrystalline cellulose

The following formiulations were prepared using the extruding equipment of example 1:

Low water-soluble drug: 100 g

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Polyethyleneglycol 400: 52.5 g

Polyethyleneglycol 4000: 250 g

Avicel PH 101: 298.75 g

Avicel CL611: 298.75 g

The solid fraction of the formulation consisting of hydrochlorothiazide (example 4), PEG 4000, Avicel PH 101 /Avicel CL 611 (commercially available from FMC Corporation, Philadelphia, Pennsylvania) was homogenised in a planetary mixer. The homogeneous mixture was then fed into the twin screw extruder at a rate of 27.6 g/min. The liquid phase (PEG 400) was continuously pumped into the io twin screw extruder at a rate of 9.2 g/min. The screw speed during the extrusion was 250 rpm. The temperature of the different zones of the twin screw extruder was set at 25°C yielding experimental temperatures of 25°C, 28°C, 27°C, 26°C and

25°C in zones 1 to 5, respectively.

In the case of florfenicol (example 5) being used as a drug instead of 15 hydrochlorothiazide, the same parameters were used and the experimental temperatures measured were 25°C, 26°C, 27°C, 27°C and 28°C for the zones (1) to (5) respectively.

The extruded granules were collected, sieved and further analysed for drug dissolution (data shown in figures 1 and 2, formulations A and C). Figure 1 shows that 100% release of hydrochlorothiazide (example 4) is obtained after 10 minutes. Figure 2 shows that 78% release of florfenicol (example 5) is already obtained after 10 minutes, and 100% after 15 minutes.