Title:  Rapidly releasing and taste-masking pharmaceutical dosage form

United States Patent:  6,221,402

Assignee:  Pfizer Inc. (New York, NY)

Filed:  September 20, 1999

PCT NO:  PCT/IB97/01471

102(e) Date:  September 20, 1999

PCT PUB. Date:  July 16, 1998

A rapidly-releasing and taste-masking pharmaceutical dosage form and a process for preparing such oral dosage form are disclosed.

DETAILED DESCRIPTION OF THE INVENTION

In the present invention, the oral dosage form comprises at least three layers, i.e., a core (also referred to as core particle) containing a pharmaceutically active ingredient, low-substituted hydroxypropyl cellulose and microcrystalline cellulose; an inner coating layer containing a water-soluble polymer; and an outer coating layer containing a saliva-insoluble polymer.

Active ingredients which usually used in this invention have a bitter taste, although those having no bitter taste can also be used. Active ingredients useful in this invention include, for example, antifungal agents such as fluconazole, pain relievers such as acetaminophen and acetylsalicylic acid, antihistamines such as diphenhydramine, doxylamine succinate and meclizine, decongestants such as pseudoephedrine hydrochloride, anti-impotence such as sildenafil, antibiotics such as azithromycin, erythromycin and cepholosporin, penicillins such as sultamicillin tosylate and amoxicillin trihydrate, enzyme inhibitors such as sulbactam sodium, anthihypertensives such as nifedipine, doxazosin mesylate and arnlodipine besylate, antidiabetics such as glipizide, bronchodilators such as pirbuterol hydrochloride and theophyfline, anti-inflammatory agents such as piroxicam and tenidap, anti-depressants such as sertaraline hydrochloride, antacids such as calcium carbonate and magnesium oxide, and non-sedative antihistamines such as cetirizine, cardiotonics such as digitoxin and digoxin.

As used herein, "microcrystalline cellulose" means purified, partially depolymerized cellulose prepared by treating alpha cellulose. Examples of the microcrystalline cellulose are those soled under the tradename of Avicel.TM. (manufactured by Asahi Chemical Industry), Ceolus.TM.(manufactured by Asahi Chemical Industry), Vivacel.TM.(manufactured by J. Rettenmaier & Sohne GmbH), and Emcocel.TM.(manufactured by Edward Mendell Co. Inc.). Suitable microcrystalline celluloses include those sold under the trade name of Avicel.TM. PH-101, PH- 102, PH-301 and PH-302 (manufactured by Asahi Chemical Industry), and mixtures of two or more of these celluloses. Most preferred are Avice.TM. PH-101.

As used herein, "low-substituted hydroxypropyl cellulose" means a low-substituted poly (hydroxypropyl) ether of cellulose, which contains not less than 5.0% and not more than 16.0 % of hydroxypropoxy groups on a dried basis. Examples of low-substituted hydroxypropyl cellulose include one sold under the trade name of LH-31 (manufactured by Shin-Etsu Co. Ltd.)

If desired, the other additives may be added to the above-mentioned core materials. Such additives include a binder such as hydroxypropyl methyl cellulose, or hydroxypropyl cellulose, a masking agent such as calcium gluconate, magnesium oxide and a lubricant such as talc and magnesium stearate.

The core particles used in this invention are preferably in a spherical form, and has an average particle diameter of 80 to 400 micrometers, more preferably 100 to 300 micrometers. Preferably, the cores may have a sphericity of 0.85 to 1.0, more preferably 0.9 to 1.0. The spherical core particles used in this invention are advantageous in that coating efficiency can be improved in subsequent coatings of an inner layer and an outer layer.

Suitable cores (also referred to as core particles) used in the present invention comprises 0.1 to 73.5, more preferably 20.0 to 40.0 of the active ingredient; 26.0 to 99.4, more preferably 28.0 to 80.0, most preferably 30.0 to 60.0 weight percent of the microcrystalline cellulose; and 0.5 to 34.0, more preferably 3.0 to 30.0 weight percent of the low-substituted hydroxypropyl cellulose, the weight percent being based on the total weight of the core material. Use of core particles with these component ratios may give good drug release profiles. When the amount of the microcrystalline cellulose is outside of the above-mentioned level, the sphericity of the resultant core particles may be decreased, resulting in decrease in coating efficiency.

In the present invention, an inner coating layer is formed on the above-mentioned core particles. The purpose of formation of the inner coating layer is smoothing of core surface and easy separation of the outer coating layer from an acidic solution of an active ingredient such as sildenafil citrate (about pH3.85). Suitable inner coating layer comprises 70.0 to 100 weight percent of a water-soluble polymer, and up to 30.0 weight percent of a water-insoluble polymer.

As used herein, the term "water-soluble polymer" means a conventional polymer for pharmaceutical use, having a solubility of more than 10 mg/ml in water. Suitable water-soluble polymers include, for example, hydroxypropylmethyl cellulose, hydroxypropyl cellulose, polyvinyl pyrolidore and polyvinyl alcohol. Most preferred water-soluble polymers used in this invention are hydroxypropylmethyl cellulose and hydroxypropyl cellulose. As used herein, the term "water-insoluble polymer" means a conventional polymer for pharmaceutical use, having a solubility of not more than 10 mg/ml in water. Suitable water-insoluble polymers include, for example, ethylcellulose, methacrylate copolymers and aminoalkyl methacrylate copolymers such as an ethyl acrylate/methyl methacrylate copolymer and an ethyl acrylate/methyl methacrylate/trimethylammonioethyl methacrylate copolymer. Commercially available water-insoluble polymers may be used. Such water-insoluble polymers are those sold under the trade name of Aquacoat (manufactured by Asahi Chemical Industry) Eudragit NE and Eudragit RS (manufactured by Rohm Pharma).

If desired, the other additives may be added to the inner coating materials. Such additives include, for example, a lubricant such as magnesium stearate or talc.

Then, an outer coating layer is formed on the above-mentioned inner layer. The outer coating layer mainly has a taste-masking effect to prevent an active ingredient from being released when a patient hold a coated drug in his mouth. Suitable outer coating layer comprises 70.0 to 100 weight percent of a saliva-insoluble polymer and up to 30.0 weight percent of a water-soluble or water-insoluble polymer, the weight percent being based on the total weight of the outer coating layer. As used herein, the term "saliva-soluble polymer" means a conventional synthetic polymer for pharmaceutical use, having a solubility of less than 10 mg/ml in neutral pH (6.0-7.5) and more than 10 mg/ml in acidic pH (1.2-5.0). Suitable saliva-insoluble polymers include, for example, aminoalkyl methacrylate copolymers such as a buthyl methacrylate/(2-dimethylaminoethyl)methacrylate/methyl methacrylate copolymer and polyvinylacetal diethylaminoacetate. Commercially available polymers may be used. Such polymers are those sold under the trade name of Eudragit E (manufactured by Rohm Pharma) and the trade name of AEA (Sankyo) (manufactured by Sankyo). Suitable water-soluble polymers used as outer coating materials include, for example, hydroxypropylmethyl cellulose and hydroxypropyl cellulose. Suitable water-insoluble polymers used as inner coating materials include, for example, ethylcellulose and Eudragit RS.

In the oral dosage forms of the present invention, the core, the inner coating layer and the outer coating layer may be contained in an amount of from 49.9 to 95.1 (more preferably from 60.0 to 87.0), from 0.1 to 45.3 (more preferably from 4.0 to 31.0, most preferably from 4.0 to 10.0) and from 4.8 to 50.0 (more preferably from 9.0 to 36.0) weight percent, respectively, based on the total weight of the dosage form. The component ratio may be determined depending on the kind of active ingredient used, the kind of polymers used, desired drug release profile and the like. In general, the resultant coated drugs with the above component ratio, may give good drug release profiles and taste-masking effects.

The process for preparing the above-mentioned oral dosage forms will be described below.

Firstly, a core or core particles may be prepared by mixing core materials containing a pharmaceutically active ingredient, low-substituted hydroxypropyl cellulose and microcrystalline cellulose and subject the mixed core materials to wet agitation granulation, dry treatment and sieving treatment in this order. Methods for preparing the core particles, which can be used in this invention, are well described in Kokai H06-56700. For example, powders of an active ingredient such as sildenafil citrate is mixed with microcrystalline cellulose, L-HPC and other additives such as a masking agent (e.g., calcium gluconate), binder (e.g. hydroxypropyl methyl cellulose), lubricant (e.g., talc), in a vessel of the granulator. Then, the mixture is granulated for 10 to 60 minutes after addition of water at room temperature by a wet agitation granulation method known to those skilled in the art. The granulated core particles may be dried with a fluidized bed dryer and sieved, to obtain substantially spherical core particles. Preferably, the core particles may be fractionated to obtain fine particles having an average particle size of 80 to 400, preferably 100 to 300 micrometers.

Then, the core particles thus prepared may be coated with an inner coating layer on the core particles by spraying with an aqueous solution containing a water-soluble polymer; and then coated with an outer coating layer on the inner coating layer by spraying with an aqueous solution containing a saliva-insoluble polymer.

The core particles may be coated by spraying with an aqueous solution composed of a water-soluble polymer, water-insoluble polymer, water and other additives such as talc in a centrifugal fluidizing granulator (e.g., CF-Granulator under the trade name of CF-360 manufactured by Freund, Inc.). The coating conditions may be determined depending on the kind of granulator used, the kind of ingredients, component ratio and the like. Suitable conditions, when using the above CF-Granulator, may be a slit air temperature of 30 to 70^oC.; a slit air rate of 200 to 350 l/min; a rotating speed of 100 to 200 rpm; a spray speed of 2 to 7 g/min; and a spray air pressure of 2 to 4 kg/Cm². After spray, the particles may be dried with, for example, a fluidized bed dryer or tray dryer.

Further, the core particles may be coated by spraying with an aqueous ethanolic solution (e.g., 80% EtOH) composed of a saliva-insoluble polymer, ethanol, water and other additives such as talc in a centrifugal fluidizing granulator (e.g., CF-Granulator under the tradename of CF-360 manufactured by Freund, Inc.). The coating conditions may be determined depending on the kind of granulator used, the kind of ingredients, component ratio and the like. The similar conditions as mentioned above may be used. After spray, the particles may be dried with, for example, a fluidized bed dryer, and then oven-cured, to obtain three-layer core particles of this invention.

In addition, to achieve a good taste and mouth feeling, a sugar coating layer may be formed on the outer coating layer of the three layer particles thus prepared. A known coating method can be used to form such sugar coating layer. For example, the three layer particles may be fed by spray solution composed of sucrose and D-mannitol dissolved in water under reasonable conditions. Xanthan gum (a polysaccharide generated from natural source) may be added to provide a good mouth feeling. The amount of the sugar coating layer may be in a range of 15.0 to 270.0 weight percent based on the total weight of the coated particle composed of the core, the inner and outer coating layers. The pharmacological dosage forms of this invention can be used in the form of fine granules, tablets, POS (powder for oral suspension), capsules or the like.

Claim 1 of 9 Claims

What is claimed is:

1. A rapidly releasing and taste-masking pharmaceutical dosage form comprising a core containing a pharmaceutically active ingredient, low-substituted hydroxypropyl cellulose containing not less than 5.0% and not more than 16.0% hydroxypropoxy groups on a dried basis, and microcrystalline cellulose, the amount of the microcrystalline cellulose being at least 26.0 weight percent based on the total weight of the core; an inner coating layer formed on the core and containing a water-soluble polymer; and an outer coating layer formed on the inner coating layer and containing a saliva-insoluble polymer, wherein the core, the inner coating layer and the outer coating layer are contained in an amount of from 60.0 to 87.0, from 4.0 to 31.0 and from 9.0 to 36.0 weight percent, respectively, based on the total weight of the dosage form.

____________________________________________
If you want to learn more about this patent, please go directly to the U.S. Patent and Trademark Office Web site to access the full patent.