GASTRIC PREPARATION

Abstract: A gastric preparation developed in order to solve the technical problems of conventional preparations, which is prepared by the bilayer packing technique and so comprises 5 to 60 %, desirably 10 to 40 % of a rapid release portion which can establish the therapeutic level of a drug shortly after the administration and 95 to 40 %, desirably 90 to 60 % of a sustained release portion which has a specific gravity of 1 or less and can maintain a satisfactory release rate.

Description: The present invention relates to quite a novel preparation having the properties of rapidly releasing a drug in the digestive tract and at the same time, retaining in the digestive tract to release gradually and optionally. BACKGROUND OF THE INVENTION Preparations having a sustained release property are clinically advantageous in many points in that the time of administration of a drug can be reduced to afford convenience to the patient, the effective concentration of a drug is maintained over a long period of time thereby to effectively keep its pharmaceutical effect, a definite concentration is maintained thereby to reduce toxicity and prevent development of side effects, and the like. In addition, release of a drug at the upper part of digestive tract is expected for a drug which is desired to directly act in stomach and in small intestine at the upper part thereof, or for a drug having absorption limited to the upper part of small intestine. For such a drug, a medical preparation with sustained gastric release has been proposed. As a technique for preparations with sustained gastric release, there is known a method utilizing selective action at the pyrolus by administering, for example, a tablet or capsule having a large diameter (Ogata et al., Pharmaceutical Factory, 3 (9), page 477, 1983). According to this method, however, there are big differences between individuals. Furthermore, residence time may vary depending upon gastric conditions and its contents so that reliability is poor as the form of administering a drug. In addition, the size of the preparation increases difficulty in administration. As another method, a preparation utilizing hydrophilic colloid (Japanese Patent Application Laid-Open No. 57315/83), a preparation obtained by molding in a hollow shape and coating an active substance on the outer layer (Japanese Patent Application Laid-Open No. 12411/80), a method using foamable microcapsules (Japanese Patent Application Laid-Open No. 76418/77), etc. have been proposed. However, these methods are complicated, require extremely severe conditions for production and require many steps, which are disadvantageous in economical consideration and poorly practicable. In addition, these methods also involve defects that preparations are destroyed by gastric peristaltic motion thereby to lose floatage and lose the sustained property. In order to solve the problems described above, there is disclosed a method for producing a medical preparation which is simple and hence highly practical and can retain a drug in stomach over a long period of time and can release a drug in a constant amount (Japanese Patent Application Laid-Open No. 43108/86). According to this method, a substance capable of forming gel in water, oils and fats which are solid at ambient temperature and a drug are mixed with each other, the mixture is heated to a temperature higher than the melting point of the oils and fats and then cooled to obtain the thus treated product. The product obtained by the method envelops therein many fine closed pores, thereby showing an apparent density of 1 or less. The product has a strength that can sufficiently stand gastric peristaltic motion and by doing so, retains the property of gradually release a drug while retaining in stomach. In this preparation, however, the entire system of the mixture comprising the gel component, oil and fat component and a drug is solidified by the heating and cooling operations. Therefore, where it is desired to increase the concentration of a drug to a therapeutical level in a short time after administration, rapid initial release of the drug cannot be expected. With respect to release control in the sustained release part, it is possible to control the release to a certain extent by changing a proportion of the gel component and the oil and fat component. However, an excellent prevention effect is exhibited with these components alone and hence, where the content of a drug is extremely small, for example, or where a sparingly soluble drug is used, the preparation might not provide a sufficient release rate corresponding to various properties of drugs. DISCLOSURE OF THE INVENTION An object of the present invention is to overcome the aforesaid technical defects and develop a more effective medical preparation. The characteristic feature of the present invention lies in having a rapid release portion and a sustained release portion in a bilayered form simultaneously and in release control being sufficiently considered. Hereinafter the medical preparation of the present invention and a method for production thereof are described in detail. The rapid release portion in the present invention is to ensure a therapeutic level of a drug in a short period of time after administration, in which rapid release is made to exhibit its effect, even when the preparation is finally heated and cooled. In general, for adding the rapid release portion, there is considered a method in which the rapid release portion is simply mixed with the sustained release portion processed for medical preparation, a method for encapsulating the rapid release portion into capsules, a method for molding a mixture, etc. JP-A-58-26816 discloses a sustained-release preparation given an element of rapid-release portion. The preparation consists of (1) spherical granules having quick-acting and (2) spherical granules having slow-acting. The preparation is made by simply mixing the many quick-acting spherical granules and the many slow-acting spherical granules at random according to conventional techniques. The preparation is one of multiple-units dosage type. EP-A-0324981 discloses a sustained-release preparation given an element of rapid-release portion. The preparation consists of (1) granules having immediate release and (2) granules having delayed release. The preparation (tablet) is made by simply mixing the many immediate release granules and the many delayed release granules at random and to compress the resulting mixture according to conventional techniques. The preparation is one of multiple-units dosage type. The preparation of the present invention has both the rapid release portion which can rapidly release a drug and the sustained release portion which has suspendability and strength and can slowly release a drug, even after the preparation is subjected to a heat treatment. In such a general method for adding the rapid release portion, the rapid release portion and the sustained release portion are present together. Therefore, when a heat treatment is performed in such a state, the rapid release portion is also hardened at the same time; in this case, rapid release from the rapid release portion cannot be expected. In the present invention, therefore, this problem has been solved by adopting a bilayer packing technique so as not to mix the rapid release portion and the sustained release portion with each other. That is, the bilayer packing technique comprises packing the rapid release portion and the sustained release portion, respectively, by intermittent packing and forming powder layer comprising bilayered rapid release portion and sustained release portion in a packed container. The resulting composition is subjected to a heat treatment after molding or packing in a gelatin capsule, or as it stands. The thus obtained preparation is a molded preparation in which only the sustained release portion is hard and the rapid release portion is present in a powdery state. A proportion of the rapid release portion contained is in the range of 5% to 60%, preferably 10% to 40%, based on 40% to 90%, preferably 60% to 90% of the sustained release portion. Where the proportion of the rapid release portion is less than 5%, packing becomes uneven, or when heated after packing in a capsule or when heated after molding, the rapid release portion and the sustained release portion are present as admixture, whereby there is a danger that rapid release from the rapid release portion might be lost. Where the proportion exceeds 60%, the volume of the sustained release portion decreases and as the result, floatage might be reduced. The construction of the sustained release portion in accordance with the present invention is an improvement of that already disclosed (Japanese Patent Application Laid-Open No. 43108/86). The present invention is to utilize this technique. In the present invention, the rapid release portion can be constructed by a drug itself in accordance with the present invention, or the drug and excipients which can be incorporated as ordinary components for medical preparations. The rapid release portion of the present invention occupies 5% to 60% of the sustained release portion. More preferably, the rapid release portion is 10% to 40%. With the proportion less than the lower limit, initial release is too small to maintain the concentration of a drug after release on a constant level. With the amount exceeding the upper limit, initial release is excessive so that a later concentration of the drug is incompatible. As the substance (a) capable of forming gel in water which is used in the present invention, any subtance can be chosen so long as it can form hydrated gel when put in water. There are, for example, cellulose derivatives, starch derivatives, dextran derivatives, polysaccharides, rubbers, polypeptides, proteins, acrylic acid derivatives, vinyl derivatives, etc. In more detail, representative examples of these substances include the following compounds. 1. Cellulose derivatives carboxymethyl cellulose, carboxyethyl cellulose, carboxypropyl cellulose, an alkali salt of carboxymethyl cellulose, an alkali salt of carboxyethyl cellulose, an alkali salt of carboxypropyl cellulose, methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose. 2. Starch derivatives alpha starch, alpha amylostarch, gelatinated starch, carboxymethylated starch, carboxyethylated starch, phosphated starch, acid-treated starch, oxidized starch, dialdehyde starch, soluble starch, thin-boiling starch, dextrin. 3. Dextran derivatives dextran, dextran sulfate, carboxylmethyldextran. 4. Polysaccharides alginic acid, pectinic acid, arabic acid, an alkali salt of arabic acid. 5. Rubbers gum arabic, tragacanth, carrageenan. 6. Polypeptides polyglutamic acid, polyaspartic acid, polylysine, polyarginine. 7. Proteins gelatin, collagen, casein, albumin, globulin, gluten. 8. Acrylic acid derivatives polyacrylic acid, polymethacrylic acid, an alkali salt of polymethacrylic acid, a copolymer of polyacrylic acid and polymethacrylic acid. 9. Vinyl derivatives polyvinylpyrrolidone, polyvinyl alcohol. As the oil and fat (b) which is solid at ambient temperature and used in the present invention, any oil and fat may be used as long as it is solid at ambient temperature. There are, for example, higher fatty acids, higher fatty acid ester derivatives, higher alcohols, higher alcohol ester derivatives, etc. In more detail, representative examples of the oil and fat include the following compounds. 1. Higher fatty acids lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, arachic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid. 2. Higher fatty acid ester derivatives esters such as glycerine, ethylene glycol, propylene glycol, sorbitol, polyethylene glycol, etc. of the fatty acids listed in 1. described above; glycerides of saturated fatty acids obtained from animals and plants; a mixture thereof and hardened oil and fat of the glycerides derived from these animals and plants; glycerides of unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, lisinolic acid, etc. and a mixture thereof. 3. Higher alcohols pentadecanol, hexadecanol (cetyl alcohol), heptadecanol (stearyl alcohol),nonadecanol, eicosanol, wool alcohol, cholesterol. 4. Higher alcohol ester derivatives cholesteryl palmitate, palmitate of plant sterol. As the substance (d) which controls release of a drug and is used in the present invention, any substance can be used so long as it is hydrophilic or swellable and when a mixture of (a) the substance capable of forming gel in water and (b) the oil and fat which are solid at ambient temperature is heated to a temperature higher than the melting point of the oil and fat, an apparent density of the resulting composition is less than 1.0. Representative examples of these subtances include the following compounds. Fine crystalline cellulose, hydroxypropyl celluose of low substitution degree, corn starch, mannitol, refined sugar, lactose. As the drug (c) used in the present invention, any kind of drug can be used so long as, when a mixture of (a) the substance capable of forming gel in water, (b) the oil and fat which are solid at ambient temperature and (d) the substance which controls release of a drug is heated to a temperature higher than the melting point of the oil and fat, an apparent density of the resulting composition is less than 1.0. Representative examples of these subtances include the following compounds. 1. Antiinflammatory agents Indometacin, Aspirin, Dichlorofenac sodium, Ketoprofen, Ibuprofen, Mefenamic acid, Dexamethasone, Dexamethasone sodium sulfate, Hydrocortison, Prednisolone, Azulene. 2. Antiulcer agents Sulpiride, Cetraxate hydrochloride, Gefarnate. 3. Coronary dilators Nifedipine, Isosorbitol dinitrate, Nitroglycerine, Diltiazem hydrochloride, Trapidil, Dipyridamole, Dilazep hydrochloride, methyl 2,6-dimethyl-4-(2-nitrophenyl)-5-(2-oxo-1,3,2-dioxaphosphorinan-2-yl)-1,4-dihydropyridine-3-carboxylate. 4. Peripheral vasodilators Ifenprodil tartrate, Cinepazide maleate, Cyclandelate, Cinnarizine, Pentoxyfylline. 5. Antibiotics Ampicillin, Amoxicillin, Cefalexin, Erythromycin ethyl succinate, Bacampicillin hydrochloride, Minocyclin hydrochloride. 6. Urinary antiseptics Pipemidic acid, Nalidixic acid. 7. Antipyretics Aspirin, Phenacetin, Isopropylantipyrine, Acetaminophen, Benzydamine hydrochloride. 8. Antispasmodics Propantheline bromide, Atropine sulfate, Oxapium bromide, Timepidium bromide, Butylscopolamine bromide. 9. Antitussives, anti-asthmatic agents Theophylline, Aminophylline, Methylephedrine hydrochloride, Procatechol hydrochloride, Trimetoxynal hydrochloride, Codein phosphate, Cromoglicate Sodium, Tranylast, Clofedanol, Dextromethorphan hydrobromic acid. 10. Diuretics Furosemide, Acetazolamide. 11. Amyotonic agents Chlorphenesin carbamate, Triperizone hydrochloride, Eperizone hydrochloride. 12. Cerebrometabolism improving agents Hopatenic acid Calcium, Meclofenoxate hydrochloride. 13. Minor tranquilizers Oxazolam, Diazepam, Clotiazepam, Metazepam, Temazepam, Fludiazepam. 14. Major tranquilizers Sulpiride, Clocapramine hydrochloride, Zotepine. 15. β-Blockers Pindolol, Propranolol hydrochloride, Carteolol hydrochloride, Metoprolol tartrate, Labetalol hydrochloride. 16. Anti-arrhythmic agents Procainamide hydrochloride, Disopyramide, Ajimalin, Quinidine sulfate 17. Agent for the treatment of gout Allopurinol. 18. Blood coagulation inhibitor Ticlopidine hydrochloride. 19. Anti-epileptic agents Phenytoin, Valproate Sodium. 20. Anti-histamic agents Chlorphenyramine maleate, Clemastine fumarate, Mequitazine, Alimemazine tartrate, Cycloheptazine hydrochloride. 21. Anti-vomiting agents Difenidol hydrochloride, Metoclopramide, Domperidone, Betahistine mesylate. 22. Antihypertensive agents Dimethylaminoethyl reserpinate hydrochloride, Rescinnamine, Methyldopa, Prazosin hydrochloride, Clonidine hydrochloride, Butofrazine. 23. Sympathomimetic agents Dihydroergotamine mesylate, Isoproterenol hydrochloride, Etilefrine hydrochloride. 24. Expectorants Bromhexine hydrochloride, Carbocistein, Ethylcysteine hydrochloride, Methylcysteine hydrochloride. 25. Oral agents for the treatment of diabetes Glibenclamide, Tolbutamide, Glymidine Sodium. 26. Agents for circulatory organs Ubidecarenone, ATP-2Na. 27. Iron agents Ferrous sulfate, Dry iron sulfate. 28. Vitamins Vitamin B₁, Vitamin B₂, Vitamin B₆, Vitamin B₁₂, Vitamin C, folic acid. 29. Agents for the treatment of pollakiuria Flavoxate hydrochloride, Oxybutynin hydrochloride, Terodiline hydrochloride, 4-diethylamino-1,1-dimethyl-2-butynyl (±)-α-cyclohexyl-α-phenylglycolate hydrochloride monohydrate. FUNCTION OF THE INVENTION It is confirmed that, where the preparation in accordance with the present invention is put in an aqueous medium (for example, gastric juice, artificial gastric juice), the rapid release portion is firstly released immediately and a hydrated gel layer is then formed at the interface between the medium and the sustained release portion, whereby a drug in the preparation is slowly released and invasion of the liquid into the inside of the preparation is prevented to maintain floats over a long period of time. Also in this case, in the preparation in accordance with the present invention, the phenomenon of excessive prevention which might be caused, for example, where the drug is contained in an extremely small amount, or where a sparingly soluble drug is used can be avoided. That is, by adding the substance in accordance with the present invention which controls release of the drug, the preparation exhibits the effects of accelerating permeation of the liquid into the inside of the preparation, assisting a rate of hydration and accelerating separation of the hydrated gel layer. This is because the aubstance which controls the release of the drug in acccordance with the present invention is a hydrophilic porous one (e.g. microcrystalline celluose) and it has, for example, a property of swelling upon contact with water or a hydrophilic property (e.g. lactose or starch) exhibiting the same effect as porous substances such as microcrystalline cellulose due to many spaces among particles and small apparent density as a result of granulating operation. The effects can be controlled by kind and addition amount of the substance which controls release of the drug in accordance with the present invention, whereby the release rate of various drugs can be optionally controlled. When peristaltic motion is caused in stomach, a preparation having a poor strength is destroyed to lose the function as a sustained release preparation. In the preparation of the present invention, there is no chance to cause such. In the preparation in accordance with the present invention, it is confirmed that the sustained release portion is not collapsed for 3 to 6 hours or longer when a disc is put on a collapse tester defined in the Japanese Pharmacopeia and a collapse test is carried out, and during the test, a definite amount of the drug component is released. BEST MODE FOR PRACTICING THE INVENTION Hereinafter the present invention is described in detail, with reference to the examples for producing the preparations in accordance with the present invention and test examples thereof. Example 1 As a rapid release portion, 3 g of riboflavin and 22 g of corn starch were taken and uniformly mixed in a mortar and 25 mg each of the mixture was packed in a capsule having a size of No. 2. Then, 3 g of riboflavin, 16 g of stearic acid, 16 g of hydroxypropyl cellulose H type and 48 g of microcrystalline cellulose were taken as a sustained release portion in a mortar and mixed uniformly. Thereafter 195 mg each of the mixture was packed in the capsule in which the rapid release portion had already been packed. The capsule was heated for 10 minutes in an electric thermostat set at 70°C, then taken out and allowed to cool to obtain the capsule containing 3 mg of riboflavin in the rapid release portion and 7 mg of riboflavin in the sustained release portion. Example 2 As a rapid release portion, 15 g of diphenidol hydrochloride and 50 g of corn starch were taken and uniformly mixed in a mortar and 65 mg each of the mixture was packed in a capsule having a size of No. 2. Then, 15 g of diphenidol hydrochloride, 42 g of stearic acid, 42 g of polyacrylic acid and 36 g of microcrystalline cellulose were taken as a sustained release portion in a mortar and mixed uniformly. Thereafter 155 mg each of the mixture was packed in the capsule in which the rapid release portion had already been packed. Thereafter the capsule was subjected to a heat treatment in the same manner as in Example 1. Thus, the capsule contains 15 mg of diphenidol hydrochloride in the rapid release portion and 35 mg of diphenidol hydrochloride in the sustained release portion. Example 3 As a rapid release portion, 30 g of riboflavin, 110 g of lactose and 110 g of corn starch were taken in a fluidizing bed granulation drier (STREA, manufactured by Fuji Industry Co., Ltd.) and 80 ml of an aqueous solution containing polyvinyl alcohol was sprayed over the mixture for granulation. Then 25 mg each of the granules was packed in a capsule having a size of No. 2. Furthermore, 15 g of riboflavin, 160 g of stearyl alcohol, 160 g of alpha amylopectin and 80 g of hydroxypropyl cellulose having a low substitution degree were taken as a sustained release portion in a fluidizing bed granulation drier followed by spraying 250 ml of purified water for granulation. After 195 mg each of the granules was packed in the capsule in which the rapid release portion had already been packed. Thereafter the capsule was subjected to a heat treatment in the same manner as in Example 1 to give the capsule in which riboflavin was contained in 3 mg in the rapid release portion and 7 mg in the sustained release portion. Example 4 As a rapid release portion, 30 g of oxybutynin hydrochloride, 110 g of lactose and 200 g of corn starch were taken in a fluidizing bed granulation drier and 120 ml of an aqueous solution containing polyvinyl alcohol was sprayed over the mixture for granulation. Furthermore, 14 g of oxybutynin hydrochloride, 76.5 g of stearic acid, 76.5 g of hydroxypropyl cellulose H type and 153 g of microcrystalline cellulose were taken as a sustained release portion in a fluidizing bed granulation drier followed by spraying 150 ml of purified water for granulation. After 40 mg the rapid release portion and 160 mg of the sustained release portion were packed in a No. 2 capsule with a capsule packing machine of Model GKF-600 (manufactured by Hefriger) which had been modified to allow these granules to pack in a bilayer, the capsule was subjected to a heat treatment in the same manner as in Example 1 to give the capsule containing 3 mg of oxybutynin hydrochloride in the rapid release portion and 7 mg of oxybutynin hydrochloride in the sustained release portion. Example 5 As a rapid release portion, 50 g of oxybutynin hydrochloride, 150 g of lactose and 200 g of corn starch were taken in a fluidizing bed granulation drier and 200 ml of an aqueous solution containing polyvinyl alcohol was sprayed over the mixture for granulation. Furthermore, 10 g of oxybutynin hydrochloride, 77.5 g of stearic acid, 77.5 g of hydroxypropyl cellulose H type and 155 g of microcrystalline cellulose were taken as a sustained release portion in a fluidizing bed granulation drier followed by spraying 155 ml of purified water for granulation. After 40 mg the rapid release portion and 160 mg of the sustained release portion were packed in a No. 2 capsule with a capsule packing machine of Model GKF-600, the capsule was subjected to a heat treatment in the same manner as in Example 1 to give the capsule containing 5 mg of oxybutynin hydrochloride in the rapid release portion and 5 mg of oxybutynin hydrochloride in the sustained release portion. Example 6 As a rapid release portion, 10 g of oxybutynin hydrochloride, 195 g of lactose and 195 g of corn starch were taken in a fluidizing bed granulation drier and 150 ml of an aqueous solution containing polyvinyl alcohol was sprayed over the mixture for granulation. Furthermore, 18 g of oxybutynin hydrochloride, 190 g of hardened castor oil, 82 g of methyl cellulose (METOROSE SM-25, SHIN-ETSU KAGAKU Co.) and 30 g of microcrystalline cellulose were taken as a sustained release portion in a fluidizing bed granulation drier followed by spraying 200 ml of purified water for granulation. After 40 mg the rapid release portion and 160 mg of the sustained release portion were packed in a No. 2 capsule, the capsule was heated in an electric thermostat set at 100°C for 10 minutes, then taken out and allowed to cool to room temperature to give the capsule containing 1 mg of oxybutynin hydrochloride in the rapid release portion and 9 mg of the same drug in the sustained release portion. Example 7 As a rapid release portion, 32 g of methyl 2,6-dimethyl-4-(2-nitrophenyl)-5-(2-oxo-1,3,2-dioxaphospholynan-2-yl)-1,4-dihydropyridine-3-carboxylate, 184 g of lactose and 184 g of corn starch were taken in a fluidizing bed granulation drier and 130 ml of an aqueous solution containing polyvinyl alcohol was sprayed over the mixture for granulation. Furthermore, 12.8 g of methyl 2,6-dimethyl-4-(2-nitrophenyl)-5-(2-oxo-1,3,2-dioxaphospholynan-2-yl)-1,4-dihydropyridine-3-carboxylate, 147.6 g of stearic acid, 147.6 g of hydroxypropyl cellulose H type and 52 g of microcrystalline cellulose were taken as a sustained release portion in a fluidizing bed granulation drier followed by spraying 150 ml of purified water for granulation. After 20 mg the rapid release portion and 180 mg of the sustained release portion were packed in a No. 2 capsule with a capsule packing machine of Model GKF-600, the capsule was subjected to a heat treatment in the same manner as in Example 1 to give the capsule containing 1.6 mg of methyl 2,6-dimethyl-4-(2-nitrophenyl)-5-(2-oxo-1,3,2-dioxaphospholynan-2-yl)-1,4-dihydropyridin-3-carboxylate in the rapid release portion and 6.4 mg of methyl 2,6-dimethyl-4-(2-nitrophenyl)-5-(2-oxo-1,3,2-dioxaphospholynan-2-yl)-1,4-dihydropyridine-3-carboxylate in the sustained release portion. Example 8 As a rapid release portion, 20 g of 4-diethylamino-diethyl-2-butynyl (±)-α-cyclohexyl-α-phenylglycolate hydrochloride monohydrate, 190 g of lactose and 190 g of corn starch were taken in a fluidizing bed granulation drier and 1530 ml of an aqueous solution containing polyvinyl alcohol was sprayed over the mixture for granulation. Furthermore, 24 g of 4-diethylamino-1,1-dimethyl-2-butynyl (±)-α-cyclohexyl-α-phenylglycolate hydrochloride monohydrate, 164.5 g of stearic acid, 164.5 g of hydroxypropyl cellulose H type and 37 g of microcrystalline cellulose were taken as a sustained release portion in a fluidizing bed granulation drier followed by spraying 200 ml of purified water for granulation. After 40 mg the rapid release portion and 130 mg of the sustained release portion were packed in a No. 3 capsule with a capsule packing machine of Model GKF-600, the capsule was subjected to a heat treatment in the same manner as in Example 1 to give the capsule containing 2 mg of 4-diethylamino-1,1-dimethyl-2-butynyl (±)-α-cyclohexyl-α-phenylglycolate hydrochloride monohydrate in the rapid release portion and 8 mg of 4-diethylamino-1,1-dimethyl-2-butynyl (±)-α-cyclohexyl-α-phenylglycolate hydrochloride monohydrate in the sustained release portion. Example 9 As a rapid release portion, 150 g of Cefalexin and 100 g of corn starch were taken in a V-shaped mixer (manufactured by FUJI Industry Co., Model FM-V-10) and mixed for 10 minutes. In a No. 0 capsule 125 mg each of the mixture is packed. Furthermore, 175 g of Cefalexin, 90 g of stearic acid, 45 g of hydroxypropylmethyl cellulose (METOROSE 90SH, SHIN-ETSU KAGAKU Co.) and 15 g of hydroxypropyl cellulose having a low degree substitution were taken as a sustained release portion in a V-shaped mixer and mixed for 10 minutes. Thereafter 325 mg each of the mixture was packed in the capsule in which the rapid release portion had previously been packed. The capsule was heated in an electric thermostat set at 100°C for 10 minutes, then taken out and allowed to cool to room temperature to give the capsule containing 75 mg of Cefalexin in the rapid release portion and 175 mg of the same drug in the sustained release portion. Example 10 As a rapid release portion, 60 g of Nifedipine, 170 g of lactose and 170 g of corn starch were taken in a fluidizing bed granulation drier and 130 ml of an aqueous solution containing polyvinyl alcohol was sprayed over the mixture for granulation. Furthermore, 24 g of Nifedipine, 118 g of hardened castor oil, 118 g of hydroxypropyl cellulose L type and 60 g of microcrystalline cellulose were taken as a sustained release portion in a fluidizing bed granulation drier followed by spraying 150 ml of purified water for granulation. After 20 mg the rapid release portion and 160 mg of the sustained release portion were packed in a No. 3 capsule, the capsule was subjected to a heat treatment in the same manner as in Example 6 to give the capsule containing 3 mg of Nifedipine in the rapid release portion and 12 mg of the same drug in the sustained release portion. Example 11 As a rapid release portion, 54 g of chlorpheniramine maleate, 160.5 g of lactose and 160.5 g of corn starch were taken in a fluidizing bed granulation drier and 100 ml of an aqueous solution containing polyvinyl alcohol was sprayed over the mixture for granulation. Furthermore, 16.8 g of chlorpheniramine maleate, 104.8 g of stearic acid, 156.8 g of polyacrylic acid and 112 g of microcrystalline cellulose were taken as a sustained release portion in a fluidizing bed granulation drier followed by spraying 100 ml of purified water for granulation. After 25 mg the rapid release portion and 195 mg of the sustained release portion were packed in a No. 2 capsule with a capsule packing machine of Model GKF-600, the capsule was subjected to a heat treatment in the same manner as in Example 1 to give the capsule containing 3.6 mg of chlorpheniramine maleate in the rapid release portion and 8.4 mg of chlorpheniramine maleate in the sustained release portion. The excellent properties of the preparation in accordance with the present invention can be confirmed by the following experiments Experiment 1. Dissolution Test According to the second method (paddle method) in dissolution test defined in the Japanese Pharmacopeia, sample is sunk in first solution with a sinker. Stirring is performed at a paddle rotary number of 100 rpm, whereby a dissolution rate of each ingredient is determined. Oxybutynin hydrochloride and 4-diethylamino-1,1-dimethyl-2-butynyl (±)-α-cyclohexyl-α-phenyl glycolate hydrochloride monohydrate are subjected to sampling every time and determined by high performance liquid chromatography. In the case of riboflavin, absorbance is determined at 445 nm. The results are shown in Figs. 1 through 3. Experiment 2. Determination of buoyancy Utilizing a micro loading converter (UT-100GR: manufactured by Shinkoh Minebea), an attachment for fixing a capsule is mounted to the converter and buoyancy of the capsule is determined every time during the dissolution test. The results are shown in Fig. 4. The preparation of the present invention releases a drug slowly and maintains release of the drug controlled to an optional rate, after the preparation is put in water and its rapid release portion is rapidly released. It is evident that by such, the form having both rapid release property and sustained released property is obtained. The foregoing results reveal that where the preparation of the present invention is orally administered, the preparation enables to increase the concentration of a drug to its therapeutic level in a short period of time after administration and then its sustained release portion is floated in gastric juice or in the upper part of the gastric content, has a strength against gastric stirring motion and peristaltic motion so as not to be destroyed and slowly releases the drug in the stomach. BRIEF DESCRIPTION OF THE DRAWINGS In Fig. 1, black squares and black triangles indicate the preparation of Example 1 and the preparation of Example 3, respectively, and each represents a dissolution rate of riboflavin, wherein the abscissa shows time (minutes) and the ordinate shows dissolution rate (%), respectively. In Fig. 2, black circles, black triangles and black squares indicate the preparation of Example 4, the preparation of Example 5 and the preparation of Example 6, respectively, and each represents a dissolution rate of Oxybutynin hydrochloride, wherein the abscissa shows time (minutes) and the ordinate shows dissolution rate (%), respectively. Fig. 3 shows the preparation of Example 8 and represents a dissolution rate of 4-diethylamino-1,1-dimethyl-2-butynyl (±)-α-cyclohexyl-α-phenylglycolate hydrochloride monohydrate, in which the abscissa shows time (minutes) and the ordinate shows dissolution rate (%), respectively. Fig. 4 shows a dissolution rate of the riboflavin preparation obtained in Example 1 and buoyancy at that time. Solid line obtained by connecting black circles and dashed line line obtained by connecting black circles show dissolution curve and change in buoyancy, respectively. The abscissa, the left ordinate and the right ordinate show time (hours), dissolution rate (%) and buoyancy (mg), respectively. INDUSTRIAL APPLICABILITY As described above, the present invention has the following excellent technical effects and is useful as a device for medical drugs. (1) The preparation in accordance with the present invention shows, when put in an aqueous medium, rapid disintegration in a part of the preparation which is a rapid release portion and hence, can maintain a therapeutic level of a drug in a short period of time after administration. (2) The preparation in accordance with the present invention assures floatage in an aqueous medium and therefore, maintains its floated state in stomach to exhibit reliable sustained release. (3) The preparation in accordance with the present invention has an appropriate strength so that the preparation is not disintegrated rapidly by peristaltic motion in stomach. (4) The preparation in accordance with the present invention can provide an optional release rate so that the preparation can be designed to cope with the property of a drug. (5) The preparation in accordance with the present invention has reproducibility pertinent to a release rate in an aqueous medium so that the preparation can maintain release of an effective drug in a constant amount during being floated in stomach.

Claims: A preparation comprising both (1) and (2): (1) a rapid release portion comprising a drug or a drug and an excipient which can be mixed as an ordinary component for preparation; and, (2) a sustained release portion comprising four of (a), (b), (c) and (d): (a) a substance capable of producing gel in water, (b) an oil and fat which is solid at an ambient temperature, (c) a drug, and (d) a substance for controlling release of the drug whereby the specific gravity is not more than 1 by incorporation of many closed fine spaces therein; and, in said preparation, both (1) and (2) are present simultaneously by forming a bilayer.

Inventors: NAKAMICHI KOUICHI, USHIMARU KOUICHI, YASUURA HIROYUKI, NAKAMICHI, KOUICHI, USHIMARU, KOUICHI, YASUURA, HIROYUKI
Applicants: NIPPON SHINYAKU CO LTD, NIPPON SHINYAKU COMPANY, LIMITED
Application year: 1990
Main classification: A61K9
IPC codes: A61K9