STABLE SOLID PHARMACEUTICAL COMPOSITION CONTAINING IBUPROFEN AND CODEINE

Abstract: A solid composition comprising ibuprofen or a pharmaceutically acceptable salt thereof and codeine or a pharmaceutically acceptable salt thereof together with a sufficient amount of an insoluble salt of carboxymethylcellulose to prevent discolouration of the composition.

Description: This invention relates to pharmaceutical compositions comprising ibuprofen or a pharmaceutically accetable salt thereof and codeine or a pharmaceutically acceptable salt thereof. Ibuprofen, the chemical name of which is 2-(4-isobutylphenyl)propionic acid, is a well-known medicament with anti-inflammatory, antipyretic and analgesic activities. The uses of ibuprofen include the treatment of pain and inflammation in muscoskeletal disorders such as rheumatic disease and the treatment of pain in a variety of other disorders, for example headache, neuralgia and dysmenorrhoea. Codeine, the chemical name of which is 7,8-didehydro-4,5-epoxy-3-methoxy-17-methylmorphinan-­ 6-ol, is also a well-known medicament and has analgesic, narcotic, antispasmodic and antitussive activities. On some occasions it is advantageous to provide a formulation containing a combination of ibuprofen and codeine, for example in the treatment of post-operative pain, dysmennorhoea, pain due to trauma, e.g. sprains, and post-extraction dental pain (see for example Cooper et al, Journal of Human Pharmacology and Drug Therapy, 1982, volume 2, number 3, p. 162-167). It has been found however, that the storage properties of pharmaceutical compositions comprising an admixture of ibuprofen and codeine are generally unsatisfactory. This is most clearly seen in a tablet where, after a short period of time, the tablet presentation becomes unacceptable. This may take the form of discolouration, expansion or cracking of the tablet which may eventually lead to the break up of the tablet. Excipients which may be incorporated in typical dosage forms include one or more of binders, diluents, disintegrants, lubricants or stabilisers The degree of discolouration, cracking or expansion may vary according to the choice and amounts of excipients used to form the composition. Some systems of excipients and active ingredients interact to a greater extent than others. It has been observed, for example that when well-known disintegrants such as cross-linked polyvinylpyrrolidones, croscarmellose sodium, maize starches, sodium starch glycollate and a commercially available mixture of 17% protein and 80% high molecular weight polysaccharide, sold under the trade name Emcosoy, are incorporated in solid compositions comprising ibuprofen and codeine, a satisfactory storage stability is not achieved. In particular, the appearance and form of a tablet containing ibuprofen, codeine and the above-mentioned disintegrants becomes unacceptable after a short period of time. The problem of interaction is addressed in European Patent Application 159852, with particular emphasis on the problem of providing a satisfactory pharmaceutical composition containing codeine or its salts and other non-steroidal analgesics (including ibuprofen), as interaction causes discolouration of the product and adversely affects the stability of the active ingredients. A multi-stage process is disclosed in EP 159852 which minimises contact between the active ingredients in order to improve the stability of the resulting product. The process comprises blending one of the active ingredients with a binder and a filler; wet granulating the mixture so produced in the presence of a solvent; drying the granulated mixture; sizing the granulated mixture; and blending the mixture with one or more other pharmaceutically active ingredients. However, it is desired to provide an ibuprofen/codeine composition which is stable on storage without involving complex formulation stages. Unexpectedly, it has now been found that when insoluble salts of carboxymethylcellulose are incorporated in a solid composition comprising ibuprofen and codeine, the composition is stable on storage. Calcium carboxymethylcellulose is a known disentegrant. The above discovery, however, is surprising in view of the instability of ibuprofen/­ codeine compositions containing other well-known disintegrants. Accordingly, the present invention provides a solid composition comprising ibuprofen or a pharmaceutically acceptable salt thereof and codeine or a pharmaceutically acceptable salt thereof, together with a sufficient amount of an insoluble salt of carboxymethylcellulose to prevent discolouration of the composition. It has been found that compositions comprising ibuprofen, codeine and an insoluble salt of carboxy­ methylcellulose are stable on storage. In particular it has been found that compositions in tablet form do not suffer from discolouration on storage and also do not expand and crack or split which would cause the tablet to break up. It has also been observed that there is no degradation of either the ibuprofen or the codeine, accordingly the compositions retain their therapeutic activity. Furthermore, the incorporation of insoluble salts of carboxymethylcellulose in the composition does not add significantly to the overall formulation cost as the salt may also function effectively in the composition as a disintegrant. In addition, this dual function provides that the insoluble salt of carboxymethylcellulose does not add substantially to the bulk of the composition. Normally sodium metabisulphite must be added to compositions containing codeine in order to achieve satisfactory chemical stability. A further advantage of the invention lies in finding that it is not necessary to add sodium metabisulphite to these compositions particularly as sulphites have been found to provoke reactions in certain suceptible people. In addition, the compositions provided according to the invention are observed to have satisfactory disintegration and dissolution properties. It will be appreciated that reference herein to ibuprofen and codeine includes a reference to the pharmaceutically acceptable salts of ibuprofen and codeine respectively. The preferred combination of active ingredients in compositions according to the invention is ibuprofen and codeine phosphate. The insoluble salt of carboxymethylcellulose is preferably the calcium salt. Calcium carboxymethylcellulose is described in teh 1985 US National Formulary, (US NF), volume XVI, p1542-3, as the calcium salt of a polycarboxymethylether of cellulose. Calcium carboxymethylcellulose may be prepared from cellulose, ie cellulose is carboxymethylated and the prohect is then converted to the calcium salt. The insoluble salt of carboxymethylcellulose is added to the composition to enhance the stability of the combination of active ingredients. In particular it is added in a sufficient quantity to avoid discolouration of the product. Conveniently the composition according to the invention comprises 1-40% by weight of an insoluble salt of carboxymethylcellulose, preferably 5-20%, advantageiously 7-12% by weight. In a preferred composition according to the invention calcium carboxymethylcellulose is incorporated to an extent of 8 to 10% by weight of the composition. Conveniently the ratio of the insoluble salt of carboxymethylcellulose to ibuprofen is in the range 1:2 to 1:10, preferably 1:3 to 1:9 parts by weight and suitably the ratio of the insoluble salt of carboxymethylcellulose to codeine is 1:0.1 to 1:2, preferably 1:0.2 to 1:1, parts by weight. Preferred compositions comprise the ingredients in the ratio of 0.5 to 1.5 parts by weight calcium carboxymethyl­ cellulose, 4 to 8 parts by weight ibuprofen and 0.4 to 1.0 parts by weight codeine phosphate. The ibuprofen and codeine may be present in the composition to the extent desired for therapeutic effectiveness. Suitably 50-1200 mg ibuprofen may be present, preferably 200-800 mg. The dosage as employed for an adult human treatment is generally in the rang from 100 to 3200 mg ibuprofen per day. Codeine may be added to the composition to an extent of 10 mg, for example 10-100 mg, preferably 30-60 mg. The dosage as employed for an adult human treatment is generally in the range 30-200 mg codeine per day. Valuable compositions comprises 10-90% by weight ibuprofen, especially 30-80% by weight. Preferably the composition comprises 1 to 15% by weight of codeine, especially 2 to 10% by weight. Advantageous compositions comprise 50 to 70% by weight ibuprofen and 4 to 10% by weight codeine, in particular codeine phosphate. The solid composition is preferably presented in the form of a tablet, however advantages may also be obtained by the incorporation of an insoluble salt of carboxymethylcullulose in other solid dosage compositions such as powder-filled and paste-filled capsules, lozenges, and compressed suppositories and pessaries. Other formulation excipients may also be incorporated into a composition according to the invention. Such pharmaceutically acceptable excipients may be added to modify the rate of drug dissolution and/or facilitate the manufacture of suitable dosage forms of the formulation. Suitable excipients which may be added include binders, soluble and insoluble diluents, stabilisers, lubricants, flow aids, oils, fats and waxes as desired. Examples of binders include polyvinylpyrrolidone, microcrystalline cellulose, gelatin and gums. In general binders may comprise up to 20% by weight of the composition. Examples of soluble diluents include lactose, sodium chloride, doctrins and sorbitol and examples of insoluble diluents include microcrystalline cellulose, calcium suphate and di- and tri-calcium phosphate. Diluents may be used by up to 50% by weight of the composition. Also there may be added to the composition up to 5% by weight of lubricants, for example searic acid, polyethylene glycol 6000, magenesium stearate; up to 5% by weight of flow aids such as colloidal silica and talc; also surfactants, e.g. sodium lauryl sulphate and Tween 80, flavourings and other oils, fats and waxes may be added as desired. If desired, the solid dosage form may be coated with any conventional coating material. In particular, tablets may be coated with a film coating. A composition according to the invention may be prepared by formulating ibuprofen, codeine and an insoluble salt of carboxymethylcellulose, together with other optional tabletting excipients in the normal way, for example by combining all the ingredients by mixing in a rotating drum to form a uniform mixture, optionally followed by compression into tablets. It will be appreciated that compositions according to the invention are particularly useful as analgesics and anti-inflammatory agents. The invention is illustrated by the following non-limitative examples. In the Examples, the ibuprofen is available from the Boots Company, Nottingham, England; codeine phosphate is available from The Boots Company or from McFarlan Smith, Edinburgh, Scotland; calcium carboxymethylcellulose is available from Carnation Gums, London, England under the trade name ECG 505; the microcrystalline cellulose is available from FMC Corporation, Philadelphia, USA under the trade name Avicel PH101; the fumed silica is available from Degussa, West Germany under the trade name Aerosil 200; and the polyvinylpyrrolidone is available from GAF (GB) Limited, Manchester, England under the trade name Plasdone K29-32; Example 1 Tablets containing 400 mg ibuprofen and 30 mg codeine phosphate Ibuprofen, the microcrystalline cellulose, 21% of the calcium carboxymethylcellulose and 50% of the fumed silica were granulated using a solution of the polyvinylpyrrolidone in isopropyl alcohol. The granules were then sized and dried to remove the isopropyl alcohol. The dry granulate was sized and blended with the remaining excipients and compressed into tablets using suitable tooling. There was found to be no discolouration and no cracking or splitting of the tablets on storage for five years either: a) at ambient temperature; or b) at 30°C and 80% relative humidity. Example 2 Tablets containing 200 mg ibuprofen and 15 mg codeine phosphate were prepared using the same proportions of ingredients as described in Example 1. There was found to be no discolouration and no cracking or splitting of the tablets on storage for five years either: a) at ambient temperature; or b) at 30°C and 80% relative humidity. Example 3 Tablets containing 400 mg ibuprofen and 60 mg of codeine phosphate The tablets were prepared in a similar way as described in Example 1. There was found to be no discolouration and no cracking or splitting of the tablets on storage for five years either: a) at ambient temperature; or b) at 30°C and 80% relative humidity. Example 4 Tablets containing 200 mg ibuprofen and 30 mg codeine phosphate were prepared using the same proportions of ingredients as described in Example 3. There has been found to be no discolouration nor any cracking or splitting of the tablets to date on tablets stored 12 months ago a) at ambient temperature and b) at 30°C and 80% relative humidity. Example 5 Tablets containing 400 mg ibuprofen and 60 mg codeine phosphate The tablets were prepared in the same way as described in Example 1. There has been found to be no discolouration nor any cracking or splitting of the tablets to date on tablets stored 12 months ago a) at ambient temperature and b) at 30°C and 80% relative humidity. Comparison The appearance of ibuprofen/codeine compositions containing calcium carboxymethylcellulose after storage was compared with ibuprofen/codeine compositions containing other disintegrants listed below:- Cross-linked polyvinylpyrrolidone Croscarmellose sodium Sodium starch glycollate Ion Exchange resin (Amberlite IRP-88) Maize starch Protein and polysaccharide (17:80) [Emcosoy] Compositions containing effective levels of the listed disintegrants were stored at 50°C and observed regularly for discolouration and for swelling or splitting. Only compositions containing calcium carboxymethylcellulose gave satisfactory results and all other formulations showed unsatisfactory storage properties due to one or more of discolouration, swelling or splitting within a 12 week period.

Claims: 1. A solid composition comprising ibuprofen or a pharmaceutically acceptable salt thereof and codeine or a pharmaceutically acceptable salt thereof together with a sufficient amount of an insoluble salt of carboxymethylcellulose to prevent discolouration of the composition. 2. A composition according to claim 1 wherein the insoluble salt of carboxymethylcellulose is calcium carboxymethylcellulose. 3. A composition according to either one of claims 1 and 2 comprising 5-20% by weight of the composition of an insoluble salt of carboxymethylcellulose. 4. A composition according to any one of claims 1 to 3 wherein the ratio of the insoluble salt of carboxymethylcellulose to ubuprofen or a pharmaceutically acceptable salt thereof is in the range 1:2 to 1:10 parts by weight. 5. A composition according to any one of claims 1 to 4 wherein the ratio of the insoluble salt of carboxymethylcellulose to codeine or a pharmaceutically acceptable salt thereof is in the range 1:0.2 to 1:1 parts by weight. 6. A composition according to any one of claims 1 to 5 comprising 0.5 to 1.5 parts by weight calcium carboxymethylcellulose, 4 to 8 parts by weight ibuprofen and 0.4 to 1.0 parts by weight codeine phosphate. 7. A composition according to any one of claims 1 to 6 comprising 30 to 80% by weight of the composition ibuprofen or a pharmaceutically acceptable salt thereof and 2 to 10% by weight of the composition codeine or a pharmaceutically acceptable salt thereof. 8. A composition according to any one of claims 1 to 7 comprising 50 to 70% by weight of the composition ibuprofen, 4 to 8% by weight of the composition codeine phosphate and 8 to 10% by weight of the composition calcium carboxymethylcellulose. 9. A composition according to any one of claims 1 to 8 in the form of a tablet. 10. A process to prepare a composition as claimed in any one of claims 1 to 9 comprising combining ibuprofen or a pharmaceutically acceptable salt thereof and codeine or a pharmaceutically acceptable salt thereof with a sufficient amount of an insoluble salt of carboxymethylcellulose to prevent discolouration of the composition, to form a uniform mixuture and optionally compressing the mixture. Claims for the following contracting States: GR, ES 1. A process to prepare a solid composition comprising ibuprofen or a pharmaceuticaly acceptable salt thereof and codeine or a pharmaceutically acceptable salt thereof together with a sufficient amount of an insoluble salt of carboxymethylcellulose to prevent discolouration of the composition, comprising combining ibuprofen or the salt thereof and codeine or the salt thereof with the insoluble salt of carboxymethylcellulose to form a uniform mixture and optionally compressing the mixture. 2. A process according to claim 1 wherein the insoluble salt of carboxymethylcellulose is calcium carboxymethylcellulose. 3. A process according to either one of claims 1 and 2 wherein the composition comprises 5-20% by weight of an insoluble salt of carboxymethylcellulose. 4. A process according to any one of claims 1 to 3 wherein the ratio of the insoluble salt of carboxymethylcellulose to ibuprofen or a pharmaceutically acceptable salt thereof is in the range 1:2 to 1:10 parts by weight. 5. A process according to any one of claims 1 to 4 wherein the ratio of the insoluble salt of carboxymethylcellulose to codeine or a phamaceutically acceptable salt thereof is in the range 1:0.2 to 1:1 parts by weight. 6. A process according to any one of claims 1 to 5 wherein the composition comprises 0.5 to 1.5 parts by weight calcium carboxymethylcellulose, 4 to 8 parts by weight ibuprofen and 0.4 to 1.0 parts by weight codeine phosphate. 7. A process according to any one of claims 1 to 6 wherein the composition comprises 30 to 80% by weight ibuprofen or a pharmaceutically acceptable salt thereof and 2 to 10% by weight of the composition codeine or a pharmaceutically acceptable salt thereof. 8. A process according to any one of claims 1 to 7 wherein the composition comprises 50 to 70% by weight ibuprofen, 4 to 8% by weight codeine phosphate and 8 to 10% by weight calcium carboxymethylcelluose. 9. A composition according to any one of claims 1 to 8 in the form of a tablet.

Inventors: MEYER, MICHAEL CHRISTOPHER, PANKHANIA, MAHENDRA GOVIND
Applicants: THE BOOTS COMPANY PLC
Application year: 1987
Main classification: A61K31
IPC codes: A61K47, A61K31, A61K9