Pharmaceutical composition.

Field of the Invention

The invention relates to a novel compostion and method for the intranasal administration of pharmaceutical substances.

Background of the Invention

Systemically active drugs have been administered by a wide variety of routes, such as orally, rectally, vaginally, subcutaneously, intramuscularly, intraveneously, etc.

Some pharmaceuticals, peptide drugs in particular, are not suitable for oral administration. For these drugs, parenteral administration is the only alternative.

The traditional mode of administration of insulin is by subcutaneous injection. Control of diabetes mellitus often requires multiple injections each day, which are painful and distressing to many patients.

Discomfort and destruction of lifestyle often deter diabetics from accepting intensive insulin treatment. For these reasons, attention has been focused on alternative routes of administration of insulin and other chronically-­needed medicaments.

Attempts have been initiated to administer insulin enterally, with and without liposome encapsulation, rectally, vaginally, and through the respiratory epithelium. Because of the limited absorption of insulin, these attempts have largely failed.

A great deal of interest has been focused on the intranasal mode of administration of drugs. Vasopressin, luteinizing hormone releasing factor ("LHRF"), adrenocorticotrophic hormone ("ACTH"), and in particular insulin, have been administered intranasally. While intra­nasal administration offers advantages over other routes, many drugs exhibit only limited absorption through the nasal mucosa. For example, insulin, when administered intranasally, neither increases serum insulin levels nor lowers blood glucose concentration. To be absorbed from the nasal mucosa to reach the blood circulation, the phar­maceutical molecules must be transported across nasal mucous membranes by means of an absorption enhancer.

Many agents have been suggested as intranasal absorption enhancers. Patent 4,476,116 discloses pharmaceutical compo­sitions for intranasal delivery including chelating agents which enhance absorption across the nasal mucous membranes. Patent 4,153,689 discloses insulin preparations for intra­nasal administration containing one or more non-ionic surface-active agents as an absorption enhancer. Bile salts such as sodium deoxycholate have also been used to increase intranasal insulin absorption. Moses et al, <u style="single">Diabetes</u><u style="single">32</u>: 1040-1047 (1983); Gordon et al, <u style="single">Proc. Natl. Acad. Sci. USA</u><u style="single">82</u>:7419 (1985). However, bile salts are undesirable since they cause nasal irritation and damage to the nasal mucosa. While much attention has been devoted to intranasal insulin formulations containing non-ionic surfactant enhancers such as laureth-9 (polyoxethylene-9-­laurylether), such surfactants cause nasal stinging, conges­tion and rhinorrhea. Salzman et al, <u style="single">N. Eng. J. Med.</u><u style="single">312</u>: 1078-1084 (1985).

What is needed is an effective enhancing agent for the transport of pharmaceutically active substances across the nasal membrane which is free of the iritation and other undesirable side effects experienced with presently-­used intranasal delivery formulations.

Summary of the Invention

A composition for the intranasal administration of pharmaceutically active substances is provided. The composition comprises an effective amount of a pharmaceu­tically active substance, a basic salt of an amino acid, and glycyrrhetinic acid. A method for administering pharmaceutically active substances by intranasal administra­tion is also provided.

Description of the Figures

<ul id="ul0001" list-style="none"><li>Figure 1 is a plot of the blood glucose concentration of an animal subject as a function of time after nasal administration of 0.1 ml of an insulin preparation according to Example 1.</li><li>Figure 2 is a plot of the blood glucose concentration of an animal subject as a function of time after nasal administration of 0.1 ml of an insulin preparation according to Example 2.</li><li>Figure 3 is a plot of the blood glucose concentration of an animal subject as a function of time after nasal administration of 0.1 ml of an insulin preparation according to Example 3a.</li><li>Figure 4 is a plot of the blood glucose concentration of an animal subject as a function of time after nasal administration of 0.2 ml of an insulin preparation according to Example 3a.</li><li>Figure 5 is a plot of the blood glucose concentration of an animal subject as a function of time after nasal administration of 0.2 ml of an insulin preparation according to Example 3b.</li><li>Figure 6 is a plot of the blood glucose concentration of an animal subject as a function of time after nasal administration of 0.2 ml of an insulin preparation according to Example 3c.</li><li>Figure 7 is a plot of the blood glucose concentration of an animal subject as a function of time after nasal administration of 0.2 ml of an insulin preparation according to Example 8.</li><li>Figure 8 is a plot of the blood glucose concentration of an animal subject as a function of time after nasal administration of 0.2 ml of an insulin preparation according to Example 10.</li><li>Figure 9 is a plot of the blood glucose concentration of an animal subject as a function of time after nasal administration of 0.1 ml of an insulin preparation according to Example 11.</li><li>Figure 10 is a plot of the blood glucose concentration of an animal subject as a function of time after nasal administration of 0.2 ml of an insulin preparation according to Example 11.</li><li>Figure 11 is a plot of the blood glucose concentration of an animal subject as a function of time after nasal administration of 0.1 ml of an insulin preparation according to Example 12.</li><li>Figure 12 is a plot of the blood glucose concentration of an animal subject as a function of time after nasal administration of 0.2 ml of an insulin preparation according to Example 13.</li><li>Figure 13 is a plot of the free insulin plasma con­centration of a human subject as a function of time just prior to and after nasal administration of 50 units of an insulin composition according to Example 6 utilizing porcine insulin.</li></ul>

Detailed Description of the Invention

Glycyrrhetinic acid, the aglycone of glycyrrhizin, may exist in a number of isomeric forms, two of which are known as 18 alpha- and 18 beta-glycyrrhetinic acid. I have found surprisingly that when glycyrrhetinic acid is combined with a basic salt of an amino acid in aqueous solution, the resulting composition significantly enhances absorption of pharmaceutical agents across the nasal mem­brane without the deliterious side effects of known nasal absorption enhancing agents.

Drugs which may be prepared for nasal administration in this manner include insulin, growth hormone, growth hormone releasing factor, glucagon somatostatin; and inter­feron; steroids such as prednisone, prednisolone, hydro­cortisone, triamcinolone, dexamethasone and betamethasone; antiinflamatory agents such as aspirin, aminopyrine, acetaminophen, ibufenac, ibuprofen, indomethacin, colehi­cine, sulpyrine, mefenamic acid, phenacetin, phenylbutazone, flufenamic acid and probenecid; antihistamine agents such as diphenhydramine hydrochloride and dexchlorpheniramine maleate; antibiotics such as penicillin or its derivatives, cephalosporin or its derivatives; erythromycin, tetracycline, furadiomycin, leucomycin; chemotherapeutic agents such as sulfathiazole and nitrofurazone; cardiac agents such as digitalis and digoxin; blood vein dialating agents such as nitroglycerin and papaverine hydrochloride; cough curing agents such as codeine; azulen; phenovalin; pepsin; vitamin U; enzymes such as lysozyme hydrochloride; other systemic agents such as anti-hypertensives and diuretics; tranquili­zers; sex hormones; and ulcer medications.

Other such pharmaceutical agents are known to those skilled in the art. The intranasal delivery composition is particularly well suited for the following pharmaceuti­cals presently marketed or under investigation for nasal delivery: vasopressin, oxytocin, luteinizing hormone releasing factor (LHRF), calcitonin, auriculin, flu vaccine and other vaccines, thyrotrophin releasing hormone (TRH), progesterone, propanol, metoclopramide, narcotic analgesics, vitamin B₁₂ and antihistamines.

The intranasal delivery compostion is also partic­ularly well-suited for the administration of insulin. Insulin may be of the animal type, such as porcine or bovine insulin. Human insulin, such as prepared by recom­binant DNA techniques, may also be used. A method for treating diabetes mellitus therefore comprises administering through the nasal mucous membrane of a patient suffering from diabetes an effective amount of an aqueous insulin solution according to the present invention which contains an amount of insulin effective in inducing regulation of blood glucose level.

Any isomer of glycyrrhetinic acid may be used in the compositions of the present invention, although the 18 alpha- and 18 beta- isomers are preferred. 18 beta-­glycyrrhetinic acid is particularly preferred. The compositions of the present invention containing glycyr­rhetinic acid have no taste or after-effects, unlike prior art intranasal compositons relying on surfactant or bile salt enhancers.

The composition contains one or more basic salts of an amino acid. Amino acids may be conveniently converted to their basic salts by treatment with an appropriate base, such as potassium hydroxide or sodium hydroxide. Suitable amino acid basic salts include, for example, the sodium or potassium salts of glycine, aspartatic acid, and glutamic acid. Either the levo, dextro or racemic forms of the amino acids may be employed. Thus, useful basic salts of amino acids for use in the present compostions include, for example, sodium glycinate, monosodium aspartate, mono­sodium L-glutamate, monopotassium L-aspartate, monopo­tassium D, L-aspartate, and other basic salts of amino acids.

The pharmaceutical substance, glycyrrhetinic acid in an amount effective to enhance absorption of the pharma­ceutical substances across nasal membranes, and the basic amino acid salt may be dissolved in an aqueous dilluent. Water may be used. Alternatively, the dilluent may comprise an aqueous buffer such as phosphate buffer.

A phosphate buffer, pH 7.6, useful as a dilluent may be prepared by combining 2.5 ml of 0.02M KH₂PO₄ and 2.12 ml of 0.02 M NaOH, and adding H₂O up to a final volume of 10.0 ml.

Generally, a concentration of glycyrrhetinic acid of about 0.25 to about 1.0% (w/v) in the composition will be sufficient to obtain an acceptable absorption enhancement across the nasal membrane. A higher or lower glycyrrhetinic acid concentration may be required, depending on the nature and dose of the pharmaceutical substance being administered. The concentration of amino acid basic salt is preferably that which will establish, on a molar basis, a concentration of basic amino acid salt equal to the concentration of glycyrrhetinic acid in the composition.

The composition may further optionally include one or more polyhydric alcohols to increase the soluability of glycyrrhetinic acid. Such polyhydric alcohols include, for example, propylene glycol, glycerin, polyethylene glycol, sorbitol, and glycerol. A hydroxide, e.g. NaOH, may also be added when needed to increase the alkalinity of the formulation to promote dissolving of glycyrrhetinic acid.

Finally, the composition may optionally include one or more preservative agents such as, for example, gentamycin, bacitracin (0.005%), or cresol.

The preparations of the invention may be produced by mixing the ingredients in any order by conventional means, taking care that the glycyrrhetinic acid becomes dissolved in the diluent.

The compositions may be administered to the nasal cavity in the form of a spray by using an atomiser, nubu­liser, sprayer, dropper or other device which insures contact of the solution with the nasal mucous membrane.

The practice of the present invention is illustrated by the following non-limiting examples. For preparations containing human insulin, a commercially available human insulin solution containing 100 units/ml and 0.2% (w/v) phenol was utilized as a source of insulin. Unless stated otherwise, each preparation contains 1% (w/v) glycyrrhetinic acid.

Example 1

100.5 mg 18 alpha-glycyrrhetinic acid are mixed in a test tube with 1 ml of a solution of 501 mg sodium glycinate in 10 ml of 0.02 M phosphate buffer (prepared by combining 2.5 ml 0.02 M KH₂PO₄ and 2.12 ml 0.02 M NaOH, and adding water up to a final volume of 10.0 ml). The mixture is stirred with a glass rod and heated to 90-100°C to dissolve the glycyrrhetinic acid by immersing the test tube in a water bath of boiling water for about 5 min. Stirring may continue until the mixture becomes homogenous. Following removal from the hot water bath, 1.0 ml of propylene glycol is added, followed by 5 drops from a solution of 502 mg glycine HCl in 10 ml of 0.02 M phosphate buffer. 0.02 M phosphate buffer is then added to raise the solution to a volume of 5 ml. One ml of this nasal absorption-enhancing solution is mixed with 1 ml of a 100 unit/ml commercially-­available human insulin solution (Squib-Novo). The result­ing preparation contains 50 units of insulin per ml.

Example 2

To 106.5 mg 18 alpha-glycyrrhetinic acid are added 1 ml of a solution of 502 mg sodium glycinate in 10 ml of 0.02 M phosphate buffer followed by mixing and heating as in Example 1. 1.5 ml of propylene glycol are then added, followed by 0.02 M phosphate buffer to 5 ml. 2.5 ml of this solution are added to 2.5 ml of a 100 unit/ml solution of human insulin. The insulin concentration in this final preparation is 50 units/ml.

Example 3a

To 100.3 mg 18 beta-glycyrrhetinic acid are added 1 ml of a solution containing 1005 mg sodium glycinate per ml of distilled water, followed by mixing and heating as in Example 1. 1 ml glycerin is then added, followed by water up to 5 ml. 2 ml of this preparation are added to 2 ml of a human insulin solution of 100 units per ml to yield a final insulin preparation of 50 units per ml insulin.

Example 3b

The preparation of Example 3a is repeated except the amount of glycyrrhetinic acid is reduced to 0.5% (w/v).

Example 3c

The preparation of Example 3a is repeated except the concentration of glycyrrhetinic acid is reduced to 0.25% (w/v).

Example 4

To 200.5 mg 18 beta-glycyrrhetinic acid are added 1.5 ml of a solution of 1005 mg sodium glycinate in 10 ml water, followed by mixing and heating as in Example 1. 1 ml of glycerin is then added. 2 ml of this preparation is com­bined with 2 ml of a human insulin solution containing 100 units per ml of insulin, which yields a final preparation containing 50 units of insulin per ml.

Example 5

50 mg sodium glycinate are added to 0.5 ml of 0.02 M phosphate buffer and 50 mg 18 beta-glycyrrhetinic acid and mixed until liquid. 0.5 ml of glycerin is then added. 50 mg of insulin crystals (24 units per mg) are dissolved in 1 ml of 0.1 N HCl, which is then added to the above mixture. Addition of phosphate buffer up to 5 ml provides a final preparation containing 240 units of insulin per ml.

Example 6

0.5 ml of glycerin and 2 ml of water are added to 2.5 ml of the final preparation from Example 4. 5 ml of the resulting solution is combined with 5 ml of a human insulin solution of 500 units per ml. The final preparation con­tains 250 units of insulin per ml and 0.5% (w/v) of 18 beta-glycyrrhetinic acid.

Example 7

To 90.5 mg of 18 beta-glycyrrhetinic acid are added 1 ml of a solution consisting of 504 mg L-aspartic acid monosodium salt per ml of water. Following mixing and heating as in Example 1, 0.2 ml of 1 N NaOH, 1 ml of glycerin, and water up to 5 ml are added. The resulting solution is added to 5 ml of an aqueous human insulin solution containing 100 units of insulin per ml to yield a final preparation containing 50 units of insulin per ml.

Example 8

2 ml of a solution of 501.5 mg L-glutamic acid mono­sodium salt in 10 ml water are added to 100 mg 18 beta-­glycyrrhetinic acid, and mixed and heated as in Example 1. 0.4 ml of 1N NaOH, 1 ml of glycerin and water up to 5 ml are then added. 5 ml of a human 100 unit/ml insulin solu­tion are added to yield a final insulin preparation of 50 units per ml.

Example 9

1 ml of a solution of 510 mg L-aspartic acid mono­potassium salt in 10 ml water is added to 100.5 mg 18 beta­glycyrrhetinic acid, followed by mixing and heating as in Example 1. 0.2 ml 1N NaOH solution, 1 ml of glycerin and water up to 5 ml are then added. This solution is combined with 5 ml of a human insulin solution containing 100 units insulin per ml. The final preparation contains 50 units of insulin per ml.

Example 10

To 100.5 mg 18 beta-glycyrrhetinic acid are added 1 ml of a solution containing 510 mg D,L-aspartic acid mono­potassium salt in 10 ml water, followed by mixing and heating as in Example 1. 0.2 ml 1N NaOH, 1 ml of glycerin and water up to 5 ml are then added. This solution is mixed with 5 ml of a human insulin solution containing 100 units per ml insulin to provide a final preparation con­taining 50 units of insulin per ml.

Comparative Example 11

1 ml of a 100 unit/ml human insulin solution was mixed with 1 ml of distilled water. This diluted solution contain­ing 50 units/ml insulin was used as a control.

Comparative Example 12

1 ml of a human insulin solution containing 100 units/ml of insulin were mixed with 1 ml of phosphate buffer, pH 7.6. The diluted solution of 50 units/ml insulin was used as a control.

Comparative Example 13

A sham preparation was prepared according to Example 3a, but omitting the insulin.

The hypoglycemic effect of the above preparations was confirmed in animal glucose monitoring studies utilizing continuous glucose monitoring with the device described in <u style="single">J. Clin. Endocrinol. Metab.</u><u style="single">53</u>: 1145 (1984). The device con­sists of a system for nonthrombogenic blood withdrawal coupled to a system for blood glucose measurement. The blood withdrawal system includes a disposable sterile intravenous needle and catheter connected to a peristaltic pump. The inside wall of the catheter is coated with tridodecyclmethylammonium chloride complexed with heparin to provide a nonthrombogenic surface. Blood is continuously withdrawn at a rate of 12 ml/hr from the experimental animal via the nonthrombogenic catheter. The blood is diluted in a Plexiglass mixing chamber with six volumes of phosphate buffer solution (0.015 M; pH 7.4) containing 10 IU/ml heparin and then moved into the device's sensory chamber. The sensory chamber contains a glucose-sensing system comprising a glucose sensing probe, a digital display and a digital graphic recorder.

Animal Study

Six preconditioned female mongrel hound dogs treated for worms, weighing 19-20 kg, were fasted overnight and anesthetized in the morning with intraveneous "NEMBUTAL" sodium pentobarbital (250 mg initial dose, 25 mg every 30 minutes for maintenance). Continuous glucose monitoring was then initiated, using the device described above, upon inserting the catheter into one of the major veins of the animal's front leg. A medicine dropper was inserted through the nasal opening into the nasal cavity. A plastic tubing was inserted through the medicine dropper into the nasal cavity. A prepration according to one of the above Examples was administered by injection into the plastic tubing with a small syringe. The solution was then blown into the nasal cavity of the animal. Blood glucose level was contin­uously monitored. The resulting decrease in blood glucose level for the insulin dosages in Table 1 are recorded in Figures 1 to 12. <tables id="tabl0001" num="0001"><img file="EP0285367A2_D0001.tif" /></tables>

The effectiveness of the insulin preparation of the invention is indicated by a substantial decrease in blood glucose level (Figures 1-8) in relation to the comparative examples lacking either glycyrrhetinic acid (Figures 9-11) or insulin (Figure 12). The results indicate that glycyr­rhetinic acid is effective in enhancing absorption of insulin across the nasal membrane.

The preparations of the comparative examples lacking glycyrrhetinic acid caused an insignificant decrease in blood glucose from 70 mg% to 60 mg% over seven hours. Preparations containing glycyrrhetinic acid and five units of insulin induced marked decreases in blood glucose con­centration in only 40 to 50 minutes (Figures 1, 2 and 3). The effect was even greater in those animals receiving 10 unit insulin doses (Figures 4, 5, 6, 7 and 8).

Human Study

A preparation according to Example 6, except for the substitution of a porcine insulin solution of 50 units/ml insulin (Eli Lilly &amp; Co.) for human insulin, was administered to a diabetic patient as follows. The basal free plasma insulin concentration was measured as 2 mg/ml. The patient received a dose of the preparation equivalent to 50 units of insulin at time T=0 from a nasal nebulizer (Pfiffer Inc., Princeton Jct, NJ). The tip of the nebulizer was introduced through the nasal aperature. The patient was instructed to inhale as the plunger was depressed, deliver­ing the preparation as a spray of droplets into the upper and inner areas of the nasal cavity. Twenty minutes after administration, the concentration of free insulin in the patient's blood increased to 28 mg/ml. The free insulin level fell to 9 mg/ml 50 minutes after administration, and to the basal level of 2 mg/ml at 80 minutes. See Figure 13. The patient reported no iritation or stinging.

Example 14

- Human Growth Hormone

Example 3a was repeated except tht 7 mg of human growth hormone was substituted for insulin.

The present invention may be embodied in other speci­fic forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.