PHARMACEUTICAL COMPOSITION

Abstract: The present invention relates to a process for preparing a rapidly disintegrating core granulate containing a pharma­ ceutically active compound, whioh granulate is optionally intended to be coated with a release determining coating, as well as such cores, whereby one adds a pharmaceutically active compound, optionally together with an emulsifier, to a solvent, and optionally treats the composition obtained intensively, optionally while reducing its particle size, distributes the treated composition obtained over a bed of a solid, preferably water soluble material, and dries the agglomerates thus obtained to the formation of a rapidly disintegrating core granulate.

Description: Technical field The present invention relates to a rapidly disintegrating and in relation to the pure, untreated pharmaceutically active compound present therein, a rapidly releasing core granulate, and a process for its preparation. The object of the present invention is primarily to obtain a composition, which gives a high bioavailability and the desired plasma concentration-time profile with regard to substantially hardly soluble therapeutically active compounds by creating the composition as a rapidly disintegrating, rapidly releasing core granulate, whereby the disintegration of the granulate with reference to place and time can be regulated in a simple way by means of a release controlling protecting coating. A further object is to obtain a rapidly disintegrating core, the disintegration of which with regard to place and rate per se is controlled by a protecting coating controlling the place and time. The background of the invention It is since long known that bioavailability particularly of hardly soluble active compounds is highly dependent on the particle size of the active compound-or its specific surface area. The greater the area-the greater the solubility rate in gastrointestinal juice of the particle prior to absorption through the mucous membranes. It is, however, known that bioavailability can not always be improved as desired, only by preparing the compound in a very fine particulate form (micronizing). These difficulties are particularly pronounced when the substance in spite of a small particle size is released during a long time period and over a long distance in the gastrointestinal tract. This is also a problem using compounds having a medium solubility, and which are absorbed over a very small part of the intestine - they show a so called absorption window. Hereby the compounds having a medium solubility can show a diminished bioavailability. Hereby it is particularly important that the compound is released in the right place and in a complete way during a time period being short enough. EP-A-0 164 587 discloses a solid composition of nifedipine with an improved bioavailability comprising 1 part per weight of nifedipine and 1-20 parts weight of an easily watersoluble filling agent and other inert agents. The filling agent is lactose and/or mannitol. The composition is obtained by granulation of nifedipine, a watersoluble material, cellulose, hydroxypropylmethyl cellulose, a tenside or an emulsifier. JP Laid open Patent publication 58-109412 (Patent Abstracts of Japan, vol. 7, no. 209 (C-189) (1354), Sept. 14, 1983 discloses a nifedipine composition which is prepared by adding carboxymethylethylcellulose and/or ethyl cellulose to nifedipine, which composition is said to have improved disintegration, elution, and absorption properties. The demands on modern pharmaceuticals are thus great, preferably with the intention of reaching a maximal therapeutical effect using a minimum amount of compound in order thereby to reduce the frequency of and the degree of side effects, as well as inter- and intra individual variations. In order to obtain this a process step is required that really gives an increased rate to complete dissolution of the compound, which dissolution can be controlled to take place in any desired place in the gastrointestinal tract. This dissolution must thereby be carried out in such a way that precipitation and recrystallization of the compound is avoided. Description of the present invention It has now surprisingly been shown possible to be able to solve the above given problems and to obtain a rapidly disintegrating core granulate, wherein a pharmaceutically active compound shows a high availability, whereby the process of the present invention is characterized in that a solution or suspension of a pharmaceutically active compound in a water:alkanol mixture having the ratio water:alkanol 40-80:60-20 is provided with an emulsifier/tenside having a HLB-value corresponding to the solubility properties of the pharmaceutically active compound to the formation of a pumpable composition, which is subjected to an intense treatment, whereupon the treated composition thus obtained is distributed over a bed of at least one solid material having a large effective surface, which material has nonbinding properties to said active compound, and which material encompasses micro-crystalline cellulose in an amount of up to 25 % by weight of the final composition, and at least one disintegrating agent in an amount of up to 25 % by weight of the final composition, whereby an agglomerate is obtained which is dried to a granulate having irregular or spherical shape. It is possible in spite of the inclusion of micro-crystalline cellulose, which has a binding effect, to obtain a rapid disintegration into primary particles by means of the addition of water:alkanol. The water is hereby necessary to obtain a formation, while the alkanol has turned out to have a positive impact on the disintegration in spite of the binding effect of the micro-crystalline cellulose. The pharmaceutically active compound can be protected, as evident from the following, against crystal growth in the dissolution stage by adding, as shown above, an emulsifier. Further characteristics are evident from the accompanying claims. By means of the present invention a rapidly disintegrating and releasing granulate or core is obtained, which preferably can be provided with a release controlling coating so that the disintegration and the release take place at the suitable place and with a suitable rate after the administration. It has also turned out that one obtains a higher bioavailability. Pharmaceutically active compounds which are hardly soluble in water or gastrointestinal juice relates to defined hardly soluble compounds and compounds which have a medium solubility. By defined hardly soluble compounds those are primarily regarded that has a solubility of <1000 mg/l, and the ones which have a medium solubility, particularly those having an absorption window, are those having a solubility of 1-10 g per liter. In the former group the following are present, i.a., nifedipine, nimodipine, nivadipine, nitrendipine, nisolidipine, niludipine, nicardipine, felodipine, omeprazole, spironolactone, griseofulvine, furosemide, terbutaline. In the latter group i.a. such compounds are present as L-dopa, riboflavine, digoxine. The amount of active compound in the final core is at most 60 % by weight, normally, however, preferably 20-30 % by weight. The emulsifier used shall have a HLB-value, i.e., a hydrophilicity-lipophilicity value that substantially corresponds with the solubility properties of the active compound. Emulsifiers that fulfill such conditions are polyoxyethylene sorbitane fatty acid esters (Tween), polyoxystearate, polyethylene glycol. The emulsifier is added in an amount of 5-100 % by weight of the active compound, preferably 15-30 % by weight, or is about 5 % of the final core, however, at most 15-30 % by weight of the final core. In the group of emulsifiers/tensides wetting agents as sodium lauryl sulphate, polyoxy ethylene-polyoxy propylene copolymer (Pluronic), esters of polyhydroxy alcohols, macrogol esters, macrogol ethers, long chain alcohols, macrogol-polyoxy propyl copolymers are present. Thus one prepares a mixture of active compound, emulsifier/tenside and a solvent, as described above. The suspension thus obtained is then intensively treated in an intense mixer (homogenizer), dispersing apparatus, or a colloid mill, a pearl mill, pebble mill, or micronizing mill, whereby the active compound can dissolve and form a true emulsion together with the emulsifier, be distributed in and covered with emulsifier/tenside, or only become covered with emulsifier. The solubility is dependent on which solvent has been used. The amount of active compound when a true solution is not obtained, controls the viscosity of the suspension obtained, whereby one should always get a pumpable suspension. Per se the amount of solvent can be increased, but due to the subsequent steps it is, however, restricted. For this reason the amount of active compound will normally become at most 60 % by weight. It is apparent that the amount can be increased when one selects a solvent which dissolves the active compound and a true solution/emulsion is obtained. Suitable alcanols are methanol, ethanol, isopropanol, t-butanol. The suspension or emulsion obtained is then distributed over a bed of a solid material having a large effective surface area, whereby neither absorption nor adsorption shall take place between the active compound and the bed material. The active compound shall attach without any remaining binding. The bed material consists, preferably of a water soluble material, such as mannitol, lactose, saccharose, glucose, xylitol, sorbitol, phosphates (Na, K), urea, citrates (Na, K), ascorbic acid, fructose. The bed material can also consist of less soluble substances such as starch, Ca-phosphates, and Ca-citrate, or combinations of these two groups. The solid bed is at least 40 % by weight, preferably normally 60-90 % by weight of the final core. In order to increase the disintegration rate the solid bed includes microcrystalline cellulose in an amount of <25 % by weight, preferably 2-15 % by weight, of the final composition and/or disintgrating agents such as low substituted hydroxypropyl cellulose (LHPC), carboxymethyl starch, crosslinked carboxymethyl cellulose, crosslinked starch, or crosslinked polyvinyl pyrrolidone in an amount of <25 % by weight, preferably 2-15 % by weight of the final composition. The effective surface area shall be large, which means a particle size of <500 µm, preferably 50-250 µm. The disintegration time for the granulate thus obtained has been determined to 5-10 min., whereafter primary particles are reobtained. In order to obtain spherical granules/cores, the moist water containing mass is extruded through an extruder; the extrudate is allowed to pass a spheronizer, and is dried. By means of this, thus obtained core it is not this that controls the absorption event in the intestine but coatings used, which are place and rate determining with regard to the release. Thus gastric juice resistent coatings are used, such as shellac, anionic polymer coatings having different pk a -values, mixtures of anionic polymers or anionic polymer(-s) and ethyl cellulose, and Eudragit RS, RL, or more simple non-gastric juice resistent coatings as sugar, water soluble cellulose derivatives and others, if an immediate dissolution in the abdomen is wanted. The present invention has been tested using nifedipine as a model compound. Thereby cores where prepared having the following composition and in the following way. The moist bed obtained was extruded in an extruder (NICASYSTEM), was spheronized in a spheronizer (NICASYSTEM) and dried. In the corresponding way as in Ex. 1 the following was prepared Ex. 2) cores using isopropanol:water (40:60), as solvent; Ex. 3) cores using the double amount of Na-lauryl sulphate; Ex. 4) cores without Na-lauryl sulphate; Ex. 5) cores using water as the only solvent; Ex. 6) cores using water as the only solvent, but without intense treatment of emulsifier-active compound; Ex. 7) cores using Na-lauryl sulphate but without emulsifier Tween 80; Ex. 8) cores using Na-lauryl sulphate, without Tween 80; and without intense treatment Ex. 9) cores with Na-lauryl sulphate, without emulsifier Tween 80, water as the only solvent; Ex. 10) cores as in h) but without intense treatment; and Ex. 11) cores as in Ex. 1, however, without intense treatment. The release of active compound from the different cores were determined in a standardized test. The results are given in Table 1 below. As evident from Table 1 the addition of emulsifier and intense treatment have a determining importance for the release rate, but also the additions of ethanol and isopropanol give an apparent effect. In another test a core of Ex. 1 above was compared with a core (A), where nifedipine had been micronized together with water, whereupon emulsifier was added and the mixture was granulated with the bed material, i.e., a composition which was the same as that of Ex. 1 with regard to pure composition. The result of the release test is given in Table 2 below. The influence on the release rate of the bed consisting of solid material has also been studied. Hereby cores were prepared in accordance with Ex. 1 using lactose (Ex. 1(l)), maize starch (Ex. 1(ms)), calcium phosphate (Ex. 1(CaP)), and Calcium citrate (Ex. 1(CaCi)). The result of the release test is given in Table 3 below. Mannitol, lactose, maize starch, and calcium citrate are relatively equal during the first two hours and then particularly during the first hour, while calcium phosphate is worse. This may depend on the fact that calcium phosphate is not readily dissolved in water, but has a limited solubility. In a further test a dried slurry of Ex. 1 above was compared with a dried slurry (NIM) prepared from nifedipine ground with water, and ground to 5-10 µm particle size. The release rate for the ingoing, unground, water slurried, dried nifedipine compound (NIOM), about 50-150 µm particle size was also determined. The result is evident from Table 4. As evident from the results of Table 4 a considerably improved release is obtained using a composition prepared in accordance with the present invention. As evident from Table l above an improved release is obtained by means of the distribution over and onto the solid material.

Claims: Process for the preparation of a rapidly disintegrating core granulate comprising a pharmaceutically active substance, characterized in that a solution or suspension of a pharmaceutically active substance in an amount of up to 60 % by weight of the final composition in a water:alkanol mixture having the ratio water:alkanol 40-80:60-20 is provided with an emulsifier/tenside in an amount of 5-100 % by weight of the pharmaceutically active substance and having a HLB-value corresponding to the solubility properties of the pharmaceutically active compound to the formation of a pumpable composition, which is subjected to an intense treatment in an homogenizer, dispersing apparatus, a colloid mill, a pearl mill, a pebble mill or a micronizing mill, whereupon the treated composition thus obtained is distributed over a bed of at least one solid material in an amount of at least 40 % by weight of the final composition and having a large effective surface with a particle size of <500 µm, which material has non-binding properties to said active compound, and which material encompasses micro-crystalline cellulose in an amount of up to 25 % by weight of the final composition, and at least one disintegrating agent in an amount of up to 25 % by weight of the final composition, whereby an agglomerate is obtained which is dried to a granulate having irregular or spherical shape, the combined levels of the ingredients totalling 100 % by weight of the composition. Process according to claim 1, characterized in that the pharmaceutically active substance has a solubility of <1000 mg/litre, and is present in an amount of up to 6o % by weight of the final granule. Process according to claims 1-2, characterized in that the pharmaceutically active substance is nifedipine, nimodipine, nivadipine, nitredipine, nisoldipine, niludipine, nicardipine, fellodipine, omeprazole, spironolactone, griseofulvine, furosemide, and terbutaline. Process according to claim 1, characterized in that the pharmaceutically active substance has, on one hand a solubility of 1-10 g/litre and, on the other hand shows an absorption window at the absorption in the gastro-intestinal tract. Process according to claim 4, characterized in that the pharmaceutically active substance is L-dopa, riboflavine, digoxine, digitoxine. Process according to claim 1, characterized in that an emulsifier having a corresponding HLB-value is selected from the group consisting of polyoxyethylene sorbitane fatty acid esters, polyoxystearate, and polyethylene glycol. Process according to claims 1 and 6, characterized in that the emulsifier is selected from the group consisting of sodium lauryl sulphate, polyoxaethylene-polyoxapropylene co-polymer, esters of polyhydroxy alcohols, macrogolesters, macrogolethers, long chain alcohols, macrogol-polyoxypropylene co-polymers, as well. Process according to claim 1, characterized in that the solid bed material is one or more material from the group consisting of mannitol, lactose, saccharose, glucose, fructose, sorbitol, xylitol, phosphates (Na, K), urea, citrates (Na, K), ascorbic acid, whereby it is preferably 60-90 % by weight of the final granulate. Process according to claim 1, characterized in that the solid bed material is selected from the group of starch, Ca-phosphates, and Ca-citrates. Process according to claims 1 and 8, characterized in that the disintegrating agent is selected from the group consisting of low substituted hydroxypropyl cellulose, carboxymethylcellulose, cross linked carboxymethylcellulose, cross linked starch, or cross linked polyvinyl pyrrolidone in an amount of <25 % by weight, preferably 2-15 % by weight. Process according to claim 1, characterized in that the composition is subjected to intense treatment in a homogenizer. Process according to claim 1, characterized in that the composition is homogenized during simultaneous particle reduction in a colloid mill, pearl mill, pebble mill. Process according to claim 1, characterized in that the granulate has a disintegration time of 5-10 min. Process according to claims 1, 8 or 9, characterized in that the bed material has a particle size of preferably <250 µm. Rapidly disintegrating granulate comprising a pharmaceutically active substance, characterized of a relatively undissolvable pharmaceutically active substance in particulate form, which is provided with a coating of an emulsifier/tenside having a HLB-value corresponding to the solubility properties of the active substance or has formed a real emulsion using such an emulsifier in the presence of a solvent, and has been applied onto a solid material to the formation of an agglomerate, whereupon granulation has been carried out and obtainable in accordance with the process of one or more of claims 1-14.

Inventors: APPELGREN, CURT HENRY, ESKILSSON, EVA CHRISTINA, UVDAL, JONAS PAUL
Applicants: LEJUS MEDICAL AKTIEBOLAG
Application year: 1987
Main classification: A61K9
IPC codes: A61K9