IE62640B1 - Novel dosage form - Google Patents

Abstract

The invention relates to a oral medicine preparation multi-unit, comprising comprises a pharmacologically active substance multiple independent core body, wherein the core body is provided with a coating; the coating is composed of the water and gastrointestinal liquid the insoluble and swelling, and water-proof and gastrointestinal liquid polymer and are randomly of the polymer can form a hole of material is formed, so the unit for coating core body made of the basically of the active substance for zeroth and diffusion control release rate of release. The invention further relates to prepare the side of the preparation method thereof.

Description

* The present invention relates to an oral pharmaceutical controlled release multiple units dosage form in which individual units containing an active substance are surrounded by a coating which releases the active substance through diffusion.

TechnicaS background The term 'controlled release multiple units formulation (Bechgaard & Hegermann Nielsen, 1978) indicates a pharmaceutical formulation comprising a multiplicity (typically at least 100) of individual coated (or 'microencap10 sulated) units contained in the formulation in such a form that the individual units will be made available from the formulation upon disintegration of the formulation in the stomach of animals, including humans, who have ingested the formulation. Typically, the multiple units formulation may be a gelatin capsule or a tablet which disintegrates in the stomach to make available a multi15 plicity of coated units.

Controlled release multiple units formulations aim at a controlled release of active substance in a predetermined pattern to reduce and delay the peak plasma concentration without affecting the extent of drug availability. Due to a lower peak plasma concentration, the frequency of undesirable side-effects may be reduced, and due to the delay in the time it takes to obtain the peak plasma concentration and the prolongation of the time above the therapeutically active plasma concentration, the dosage frequency may be reduced to a dosage taken only twice or once a day, in order to improve patient com25 pliance.

A further advantage of the controlled release multiple units dosage form is that » high local concentration of the active substance in the gastrointestinal system is avoided, due to the units being distributed freely throughout the gastrointes- 30 final tract.

Drug release from a controlled release dosage form is generally controlled by a costing outside an active core. The release can be acehieved a) by diffusion: the coating swells In aqueous environment so that the active substance can diffuse through the stagnant liquids phase contained in the coating polymer, or b) by osmosis: the coating is semipermeable, i.e. only water can penetrate the coating polymer and dissolve the active substance, this will lead to a pressure buildup inside the coating, in order to allow the active to be released from the unit a hole or channel with a well defined area must be formed in the coating, this can be aochieved either by laser drilling (SE patent 435 897 - US patent 4256108 to Alza) or by incorporation of a substance which will form the channels by erosion after ingestion (US patent 4687 660 and European Patent Application 0171 457 to Wellcome), should the coating have any weak spots or cracks in it these will increase theTelease area and as a result give varying dissolution rates for different units, i.e. zero order release will not be achieved for the hole dose, or c) by erosion: the coating will disintegrate by a process dependent on, e.g. enzymes or pH and leave the active core exposed to rapid dissolution. The importance of a pH independent diffusion with respect io obtaining a repro2Q ducible rate of availability and to minimizing intra- and smersubject variations is known (GB Patent No. 1,468,172 and Bechgaard &. Baggesen, 1980). It is also known that controlled drug release in vivo can be achieved through an erodable process by enteric coating of a multiple units dosage form (Green, 1966; McDonald et al., 1977; Bogentoft et al.. 1978).

The present invention deals with multiple units dosage forms controlled by diffusion membranes. Contrary to previously known diffusion membranes used for multiple unit dosages the membrane according to the invention is nonswell&ble tin water and gastrointestinal fluids. Furthermore the polymer used must be insoluble in and impermeable to water and pores are formed In the membrane after ingestion by a pH independent erosion process. The pores will give the coating a Sponge-like appearance and will be filled with stagnant liquid where the active substance can diffuse out from tine core.

Disclosure of the invention A number of coatings employed in connection with pharmaceutical controlled release multiple units formulations have been observed to suffer from the disadvantage that they change their release characteristics in the course of time. This means that it is not possible to maintain a reproducible release rate of an active substance contained in the multiple units formulation as a variable release rate has been observed for such coatings. In accordance with the present invention, it has unexpectedly been found that by selecting a special type of controlled release system which has not previously been used or disclosed for multiple units formulations many problems connected to multiple units formulations can be avoided.

In macro scale, i.e. for tablets, controlled release systems based on coatings containing pore-creating substances has been disclosed in, e.g. the GB Patent No. 1,186,990, the US Patent No. 3,538,214 and in the US Patent No. 4,557,925. The present release system is based on the principle of coating a core including an active substance with a film essentially consisting of a polymer that Is insoluble in and impermeable to water and gastrointestinal fluids, and in which a watersoluble pore-creating substance is randomly distributed.

It is also required that the polymer is non-swellable in water and gastrointestinal fluids. When applying this controlled release system to multiple units formulations it was unexpectedly found that important advantages could be obtained.

It was thus found that it is possible to coat different types of particles, including crystals, in ordinary coating equipment, i.e. in different types of standard equipment normally available in a pharmaceutical industry. From this follows that the manufacturing process is comparatively easy and cheap. Additionally it was found that a uniform essentially zero order controlled -release rate could be obtained also when relatively non-uniform particles were used as cores. This ss usually not the case in conventional multiple units controlled release formulations. For example diffusion controlled release from multiple units where the polymer swells are dependent on the thickness of the diffusion layer which will differ with time since the polymer will release the active substance while the swelling continues. This will lead to different release rates at the beginning and end of the release period which will result in a release more similar to first order release than zero order. Osmotic controlled multiple units on the other hand are dependent on both the ability of the substances in the core to draw water into it, which may lead to lowered release rate at the end of the release period if the osmotic active and drug active substances are not the same, and the coating quality, which, if it has any weak spots or cracks in it. increases the release area. Such defects give varying dissolution rates for diffeI rent units, i.e. zero order release will not be achieved for the multiplicity of the units contained in a dose.

Another advantage of the present invention is the possibility of adjusting the release rate by changing the film thickness. In currently commercially used multiple unit systems this possibility seems to exist in a rather unpredictable manner and only up to a certain film thickness. In the present system, on the contrary, an essentially linear con slaiion exists between the release rate and the film thickness. This means that for a given type of film the release rate del o creases when the film thickness increases in a proportional manner in accordance with rick’s first law of diffusion.

It is also possible to change the release rate by changing the ratio between the pore-creating substance and the tooating polymer. This gives the present sys15 tern a unique possibility to utilize active substances with very different solubilities, which is a great advantage over the existing multiple units controlled release systems.

Thus, one aspect of the invention relates to an oral pharmaceutical controlled release multiple units formulation characterized by individual units containing an active substance, which units are provided with an outer coating consisting essentially of a polymer iriat is insoluble in, impermeable io and non-swellable in water and gastrointestinal fluids, and a water-soluble pore-creating substance which is randomly distributed in the polymer. Another aspect of the in25 vention is a formulation in which units of the type described* above are combined with uncoated units which comprise the same or another active substance for instant release thereof, and/or with non-diffusion coated units which have been provided with a coating selected from hydrophilic coatings, hydrophobic coatings, waterbased coatings and organic coatings imparting desired properties to the unit such as add or alkali resistance, storage stability, taste masking, light stability, colouring, improved processability, etc. The ratio between diffusion coated and uncoated or non-diffusion coated units in the composition may be adjusted according to, for instance, tine desired release characteristics of toe composition, but is preferably fina the range of about 10:90 to 90:10 of diffusion coated units to uncoated or non-diffusion coated units.

' The oral pharmaceutical conbolted release multiple units formulation according to the invention will typically be a gelatin capsule containing a multiplicity of the units, typically more than 100, a sachet containing a multiplicity of the units, typically more than 500, or a tablet made from a multiplicity of the units, typically more than 100, en such a manner that the tablet will after ingestion disintegrate in the stomach into a multiplicity of individual units. In each of the three above mentioned formulations the units will be freely distributed througout the gastrointestinal tract shortly after ingestion.

Detailed description of the invention Coating The coating polymer should have good filmforming and adhesive properties, and should be readily soluble in organic solvents such as acetone, methylene chlorid, methylethyl ketone or mixtures of acetone and ethanol or methylene chloride. Suitable polymers are non swelling cellulose derivates, acrylic polymers and vinyl polymers. The coating polymer is a polymer con15 taining 80-95% weight by weight vinyl chloride, 1-19% weight by weight vinyl acetate and 0-10% weight by weight vinyl alcohol. Preferably containing 8894% weight by weight vinyl chloride, 2-5% weight by weight vinyl acetate and 3-5% weight by weight vinyl alcohol.

Preferably plasticizers also are present in the coating. The amount may vary between 1 to 50% weight by weight of the coating polymer, preferably between 10 and 40%. Examples of suitable plasticizers are acetyltributylcitrate, polyethylene glycol, blown castor oil and glyceryl triacetate. Futhermore, the coating may include sodium bicarbonate as stabilizing agent in amounts be25 tween 1 and 20% weight by weight of the coating polymer, preferably 5 to 15% weight by weight of the coating polymer.

The pore-creating substance used according to the present invention should be highly water-soluble, insoluble in the solvent used for coating, pharmaco30 cologically acceptable and essentially free from own pharmacological effects in the amounts used. Especially preferred are sugars such as saccharose and lactos, and salts such as sodium chloride.

The particle size of the pore-creating substance may vary between 0.1 and 100, preferably between 0.5 and 50 pm. The ratio between the amount of pore-creating substance and coating polymer depends on the desired dissolution rate. Generally the ratio should be between 0.05 and 5, preferably bet tween 0.1 and 2.

The coating thickness is also dependent on the desired dissolution rate. It may vary between 5 and 300 pm, preferably 10 and 150 pm.

Cores The individual units of the multiple units formulations according to the invention are coated cores consisting of crystals or pellets. The crystal units are substantially monolitic crystals. The pellets are constituted by a combination of active substance and excipients. One major type of pellets consists of an excipient seed-particle with active substance applied to its surface. Typical pel· lets of this type are the so-called non-pareil* pellets where the seeds are in the form of spherical particles of saccharose. In another pellet formulation principle of this type the seeds are in the form of chrvstalline saccharose. Another major type of pellets consists of cross-sectionally substantially homogenous particles prepared e.g. wet-granulation or extrusion.

The diameter of the cores is normally about 0.1-1.5 mm, preferably about 0.41.2 mm, preferably with a range of about 0.4 mm within a specific formulation.

Active substance The active substance in the formulations according to the invention may beany active substance which is advantageously administered in a controlled release multiple units formulations. Examples of suitable active substances are found among almost all therapeutic groups, including diuretics, antiepileptics, sedatives, antiarrythmics, antirheumatics, β-blockers, Vasodilators, analgesics, bronchodilators, hormones, vitamins, oral antidiabetics, antibiotics, antihypertensives, antiinflammatory drugs, antimicrobial agents and antidepressants, polypeptides, enzymes and mucopolysaccharides.

As examples of active substances may be mentioned phenylpropanolamine, potassium chloride, quinidine salts, lithium carbonate, acetyl cystein, depyridarnol, theophylline, choline theophyllinate, dextropropoxvpbene, dextromethorphan, salbutamol, terbutaline, digoxin, furosemide, propranolol, ibuprofen, lidocaine, mepyramine, morphine, nitroglycerine, clonidine, disopyr&mide, verapamil, capiopril, prazocin, nifedipine, diltiazem, paracetamol, indomethacin, ticlopedine. oxybutynin and noscapine. Ί Among these substances, some are characterized as having a pH-independent solubility, others as having a pH-dependent solubility. Active substances having a pH-dependent solubility are preferably incorporated in cores in combination with buffering substances such as sodium bicarbonate, citric acid, succinic acid or tartaric add, in order to obtain a dissolution of active subJ stance which is substantially independent of the gastrointestinal pH variations through which the units will pass.

Method o Generally the method of producing the coated multiple unit preparation according to the invention comprises the steps of dissolving the polymer in a solvent, preparing a suspension of the pore-creating substance, mixing the suspension of pore-creating substance and the solvent solution of the polymer to form a coating fluid, prepare multiple unit cores containing an active substance in the form of crystals or pellets, applying the coating fluid to the core units, and drying the units in order to evaporate the solvent and provide polymer-coated multiple units having the water-soluble pore-creating substance randomly distributed within the coating.

The solvent for the polymer can be selected from, e.g. acetone, methylene chloride, methylethyl ketone or mixtures of acetone and ethanol or methylene chloride.

The pore-creating particles are micronized either by dry milling or by wet-mil25 ling to a defined particle size, preferably between 0.5 pm and 50 pm. The particles are dispersed in solvents such as those previously mentioned, and mixed with the terpolymer solution.

The coating fluid may, as previously stated, include a plasticizer and sodium bicarbonate.

Coloring matter can also be incorporated in the coating fluid, and insoluble f coloring materials are preferred. · 35 The coating fluid, in the form of a suspension, is then applied on drug-containing cores. A special advantageous feature is that the coating process can be performed in ordinary coating equipment, i.e. in different types of standard equipment normally available in a pharmaceutical industry. This is due to the good filmforming and adhesive properties of the coating material, and the easiness of solvent evaporation from the system. Examples of such coating equipments are pan coating in sugar-coating pans or perforated film-coating pans, Wurster coating, and other fluid-bed coating procedures. From this follows that the manufacturing process is comparatively easy and cheap.

The following examples further illustrate the invention but should not be construed as limiting to the invention.

Example 1 Theophylline is a weak acid (pKa = 8.7) which is poorly soluble in water. The cores used in this example contain 60% theophylline on non-parils and have a particle size of 0.8 -1.0 mm. These cores (1.0 kg) are coated with a coating suspension of the following composition: Terpolymer containing 92% vinylchloride, 4% vinylacetate and 4% vinylalcohol weight by weight 390 g Micronized succrose (particle size 1-10 pm) 930 g Acetyl tributyl citrate 89 g Blown castor oil 68 g Sodium bicarbonate 34 g Aceton ad 10.000 g The coating suspension is applied on the cores with an airless spray-coating device in a coating pan. Samples are taken after the application of 1.0, 2.0 and 3.0 kg of the suspension.

Table 1 shows the dissolution rate of a dose corresponding to 90 mg theophylline. The dissolution testing is performed according to the USP XXI basket method (100 rpm). There is a linear correlation between the release rate and the coating thickness, and the release rate is essentially independent of the pH. A uniform zero order release rate is observed during the major part of the release time. lablej.

Time Released amount of theophylline (%) (hours) 0.2 M TRIS buffer pH 7.4 0.1 M HCl A B C C 1 46 18 10 11 2 84 39 24 28 3 98 58 37 44 4 100 76 49 59 5 90 62 73 6 96 73 86 7 99 83 94 8 90 99 9 94 100 10 95 101 11 97 101 12 98 102 A: 2.5 mg coa ting materi ial per cm2 of the cores B: 5.9' ' - * «- C: 9.0' - Example 2 Choline theophylline is a salt of theophylline readily soluble.in water. The 25 cores used in this example contain 30% choline theophyllinate on sugar crys tals and have a particle size of 0.7 -1.0 mm. These cores (1.0 kg) are coated with a suspension of the following compositions: Terpolymer containing 92% vinylchloride, 4% vinylacetate and 4% vinylalcohol weight by weight 295 g Micronized succross (particle size 1-10 pm) 930 g Acetyl tributvl citrate 30 g Blown castor oil 23 g Sodium bicarbonate 34 g Titanium dioxide 59 g Aceton ad 10.000 g ίΟ The coating suspension is applied on the cores with an airless spray-coating device in a coating pan. Samples are taken after the application of 2.0, 2.5, 3.0 kg of the suspension.

Table 2 shows the dissolution rate of a dose corresponding to 90 mg theophylline. The dissolution rate testing according to the USP XXI basket method (100 rpm). The dissolution rate is considerably higher than in Example 1 due to the much higher solubility of the choline salt of theophylline than of pure theophylline. Despite the higher dissolution rate there is still a linear correla1 o tion between the release rate and the coating thickness.

Table 2 Time Released amount of theophylline (%) (hours) 0.2 M TRIS buffer pH 7.4 ABC 0.33 96 86 76 0.67 100 99 98 1.00 100 100 A 3.7 mg coating material per cm2 of the cores B: 4.6' • C: 5.5 - « „ * · * Example 3 Diltiazem hydrochloride is an ammonium salt readily soluble in water. The cores used in this example contain 44% diltiazem hydrochloride or non-pareils and have a parade size of 0.7 - 1.1 mm. These cores (0.9 kg) are coated with a coating suspension of the following composition.· Terpolymer containing 92% vjnylchloride, 4% vinylacetate and 4% vinylalcohol weight by weight Micronized sucerose (partide size 1-10 pm) Acetyl tributyl citrate 35 Blown castor oil ' Sodium bicarbonate Aceton ad 409 g 1 930 g g 52 g 34 g 10.000 g /. i The coating suspension is applied on the cores with an airless spray-coating device in a coating pan. Samples are taken after the application of 1.6, 2.3 and 3.0 kg of the suspension.

Table 3 shows the dissolution rate of a doze corresponding to 120 mg diltiazern hydrochloride. The dissolution testing is performed according to the USP XXI basket method (100 rpm). The solubility of this ammonium salt is si milar to that of the salt in Example 2. The dissolution rate is therefore also similar. Also here is the linear con-elation between the release rate and the o coating thickness obvious.

Table 3 Time Released amount of diltiazem hydrochloride (%) (hours) 0.05 M phosphate buffer pH 7.4 A B C 0.25 48 34 27 0.50 79 67 56 0.75 91 85 80 1.00 96 91 85 1.25 98 94 91 1.50 99 97 94 1.75 100 98 96 2.00 101 99 97 A: 6.8 mg coating material per cm2 of cores B: 9.8’ ' C: 12.4 ' ' ..... t

Claims (8)

1. Oral pharmaceutical multiple units formulation comprising individual cores containing a pharmacological active substance, said cores being 5 provided with a coating consisting essentially of a polymer, that is insoluble in, impermeable to and non-swellable in water and gastrointestinal fluids whereby said polymer is a polymer containing 8095 % weight by weight vinyl chloride, 1-19 % weight by weight vinyl acetate and 0-10 % weight by weight vinyl alcohol, and a watersoluble 10 pore-creating substance, which is randomly distributed in said polymer, whereby said coated cores form units providing an essentially zero order diffusion controlled release rate of said active substance.

2. Formulation according to claim 1, characterized in that the polymer is a 15 terpolymer containing 88-94 % weight by weight vinyl chloride, 2-5 weight by weight vinyl -acetate and 3-5 % weight by weight vinyl alcohol.

3. Formulation according to any of the claims 1-2, characterized in that the 20 pore-creating substance is «elected from the group consisting of sugars and salts.

4. Formulation according to any of the preceeding claims, characterized in that it also comprises uncoated cores containing the same or another 25 active substance for the instant release thereof.

5. Formulation according to any of the claims 1-4, characterized in that it also includes non-diffusion coated cores provided with a coating selected from hydrophilic, hydrophobic, waterbased or organic coatings.

6. Method of preparing an oral pharmaceutical multiple units formulation t. comprising individual cores containing a pharmacological active substance, said cores being provided with a coating consisting essentially of a polymer, that is insoluble in, impermeable to and non-swellable in water and gastointesnnal fluids whereby said polymer is a polymer containing 80-95 °/o weight by weight vinyl chloride, 1-19 % weight by weight vinyl acetate and 0-10 % weight by weight vinyl alcohol, and a watersoluble pore-creating substance, which is randomly distributed in said polymer, whereby said coated cores form units providing an essentially zero order diffusion controlled release rate of. said active substance, said method comprising the steps of dissolving the polymer in a solvent, preparing a suspension of the pore-creating substance, mixing the suspension of pore-creating substance and the solvent solution of the polymer to form a coating fluid, prepare multiple unit cores containing an active substance in the form of crystals or pellets, applying the costing fluid to the core units, and drying the units in order to evaporate the solvent and provide polymer-coated multiple units having the watersoluble pore-creating substance randomly distributed within the coating.

7. Method according to claim 6, characterized an. that the polymer is a terpolymer containing 88-94 % weight by weight vinyl chloride, 2-5 weight by weight vinyl acetate and 3-5 % weight by weight vinyl alcohol.

8. Method according to any of the claims 6-7 s characterized in that the pore-creating substance is selected from the group consisting of sugars and salts. g An oral pharmaceutical multiple units formulation according to clariai 1,,, substantially as hereinbefore described -and exessplified»