composition in the form of a foam containing 5-aminosalicylic acid for intra-rectal administration

Abstract: Pharmaceutical compositions suitable for intra-rectal administration in the form of a foam are described which comprise a therapeutically effective amount of 5-aminosalicylic acid, a pharmaceutically acceptable aqueous carrier therefor, and means for generating a foam. Methods for their preparation and their use in the treatment of ulcerative colitis are also described.

Description: The present invention relates to a pharmaceutical composition for rectal administration, to a method for its preparation. Ulcerative colitis is an inflammatory disease of the colon which is characterised by severe inflammation of the colonic and rectal mucosa and profuse diarrhoea and bleeding. The disease can occur at any age and affects both sexes equally. The prevalence of the disease is greatest in Western society and is estimated to be in the region of 50 to 70 sufferers per 100,000 members of the population - see, for example, the article by P. Baker, The Pharmaceutical Journal, August 6, 1988, page 180. It is known that sulphasalazine and its metabolite, 5-aminosalicylic acid (5-ASA), are useful in the treatment of ulcerative colitis and a number of products containing these active ingredients are currently sold for this purpose. A problem with 5-ASA is that it is absorbed in the small intestine and hence, when administered orally, does not reach the colon where it is required to exert a localised topical effect at the site of disease. Several solutions to this problem have been proposed. One known solution is to administer 5-ASA orally in a polymeric coating which does not break down to release the 5-ASA until the lower ileum/colon is reached. This approach has been described in, for example, US Patent 4,496,553. A drawback with this approach is that, in general, the 5-ASA is delivered to the proximal colon, but may not reach the distal colon in therapeutic concentrations. Another solution is to administer the 5-ASA directly to the colon by means of rectal administration and it is known to administer 5-ASA in this way by means of suppositories and enemas. Suppositories suffer from the disadvantage that they show relatively little spreading in the rectum/colon and thus the 5-ASA is not distributed widely throughout the diseased region. Enemas suffer from several disadvantages. Firstly, liquid formulations of 5-ASA are relatively unstable and require special precautions to be taken in order that oxidative decomposition be avoided - see US 4,657,900. US patent 4 664 256 describes an improved enema composition comprising 5-ASA. Secondly, there is the problem of leakage of the enema liquid from the rectum. Leakage leads not only to a reduction in efficacy of the treatment, since contact time of the 5-ASA with the diseased area is reduced, but can also give rise to the unpleasant problem of stained clothing. The tendency of 5-ASA to acquire a brownish colour when oxidised means that this can be a particular problem. Rectal foam products comprising hydrocortisone acetate are available, for instance the products Coloifoam®, marketed by Stafford-Miller and Predcort®, marketed by Boehringer-Ingelheim France. A further rectal foam, comprising prednisolone is available, as Predfoam®, from Pharmax Ltd. The Coloifoam product is further described by, for instance, Ruddell et al (Gut, 1980, 21, 885-889); Farthing et al (British Medical Journal, 1979, 2, 822-824) and Hay et al (British Medical Journal, 1979, 1, 1751-1753). It has now been found that the above-mentioned problems with existing rectal compositions of 5-ASA can be overcome by administering the 5-ASA in the form of an aqueous foam. The use of a foam overcomes the problem of leakage while allowing the 5-ASA to spread efficiently through the diseased region of the colon. In a first aspect, therefore, the present invention provides a pharmaceutical composition for intra-rectal administration in the form of a foam which comprises (a) a therapeutically effective amount of 5-aminosalicylic acid present in an amount between 18 and 30% (w/w) of the composition wherein the particle size of the 5-aminosalicylic acid is such that at least 95% of the particles have an equivalent sphere diameter of less than 60µ, (b) a pharmaceutically acceptable aqueous carrier therefor present in an amount from 55 (w/w) to 65% (w/w) of the composition and which contains water in an amount from 50% (w/w) to 60% (w/w) of the carrier and a water-soluble organic polyalcohol consisting of a mixture of glycerol and a polyethylene glycol, in an amount from 40% (w/w) to 50% (w/w) of the carrier (c) a surfactant which is a mixture of sorbitan mono-oleate and Polysorbate 20, in an amount less than 12% (w/w) of the composition. (d) emulsifying wax which comprises cetostearyl alcohol and a polyoxyethylene derivative of a fatty acid ester of sorbitan in in amount between 0.3 and 0.7% (w/w) of the composition, (e) colloidal silica in an amount corresponding up to 1% (w/w) of the composition. and (f) a liquid or liquefied gas propellant for generating a foam. The equivalent sphere diameter is the diameter of a sphere having the same volume as the particle; see "Particle Size Measurement", Chapter 4, T. Allen, 2nd Edn., Chapman & Hall, London, 1975. Liquid or liquefied gas propellants are well known in the art. In view of the sensitivity of 5-ASA to oxidation, a compressed air propellant is not used. Suitable propellants are hydrocarbons such as propane or butane or halogenated hydrocarbons such as chlorofluorohydrocarbons or fluorohydrocarbons. Examples of such propellants include the Arcton™ propellants obtainable from Imperial Chemical Industries Limited, Runcorn, Cheshire, U.K., the Freon™ propellants obtainable from Du Pont (U.K.), Stevenage, Hertfordshire, U.K., and the Forane propellants obtainable from Atochem, Paris, France. Preferably the propellant is selected such that its vapour pressure is in the range from approximately 200 to 350 kNM -2 . A particular propellant is a combination of dichlorodifluoromethane (e.g. Arcton 12) and 1,2-dichlorotetrafluoroethane (e.g. Arcton 114) in the weight ratio 4:6. The propellant typically is present in the composition in an amount corresponding to between 5% and 15% (w/w), for example approximately 8-10% (w/w). The carrier will be one which is compatible with the rectal and colonic mucosa. The foam compositions will generally have a pH in the range from approximately 4 to 7 and can be buffered or unbuffered. Preferably the compositions are buffered and a particular buffering agent is a mixture of disodium hydrogen orthophosphate and sodium dihydrogen orthophosphate. The compositions can also contain other ingredients such as preservatives, chelating agents and antioxidants. Typical preservatives are those such as sodium benzoate, sorbic acid and the parahydroxybenzoates, e.g. methylparahydroxybenzoate (methyl paraben) and propylparahydroxybenzoate (propyl paraben). A preferred antioxidant is sodium metabisulphite and advantageously this can be used in conjunction with a chelating agent such as a salt of EDTA, e.g. disodium edetate. The composition contains colloidal silica, for example the Aerosil™ product obtainable from Degussa Ltd. of London, U.K. Suitably the colloidal silica is present in an amount corresponding to to approximately 0.4% (w/w) of the composition. The compositions of the present invention will usually be presented in a suitable dispensing container, for example an aluminium aerosol container, fitted with a suitable metering valve. Such containers are well known in the art. Where desired, the container can be fitted or supplied together with an applicator device for insertion into the rectum to ensure more efficient administration of the foam. The compositions of the present invention suitably will be presented in a container fitted with a valve adapted to dispense volumes of from approximately 2 cm 3 to approximately 5 cm 3 . Such valves can be obtained from, for example, Lablabo of 5, Rue Roger Salengro, 92120 Montrouge, France. The present compositions can be prepared by mixing the ingredients in an appropriate manner and then filling into a suitable dispensing container, for example as described in the Examples. The compositions of the present invention would typically be used to administer approximately 1-4g of 5-ASA per day, for example by administering one or two doses of 1g 5-ASA once or twice daily. However, the amount administered will depend upon the severity of the condition and ultimately would be at the discretion of the dispensing physician. Where desired, the rectal foams could be used in conjunction with the delayed-release oral preparations of 5-ASA such as the "Asacol"™ product, i.e. the product described in European Patent No. 97651. Where desired, other therapeutically useful ingredients may be added, for example, steroids such as hydrocortisone and prednisolone. The invention will now be illustrated by means of Examples. Reference EXAMPLE 1 FOAM CONCENTRATE (WITHOUT ADDITION OF PROPELLANT) %(w/w) Weight (g) 5-Aminosalicylic Acid 15.0 150.0 Polysorbate 80 0.25 2.5 Emulsifying Wax ('Polawax NF') 0.5 5.0 Colloidal Silicon Dioxide ('Aerosil 200') 0.5 5.0 Sodium Metabisulphite 0.3 3.0 Disodium Edetate, dihydrate 0.1 1.0 Methylparahydroxybenzoate 0.2 2.0 Propylparahydroxybenzoate 0.04 0.4 Disodium Hydrogen Orthophosphate, 12H 2 O 1.19 11.9 Sodium Dihydrogen Orthophosphate, 2H 2 O 0.52 5.2 Glycerol 15.0 150.0 Macrogol 300 (Polyethylene Glycol 300) 15.0 150.0 Water, Deionised 43.4 434.0 Reference EXAMPLE 2 25% 5-ASA FOAM %(w/w) Weight (g) 5-Aminosalicylic Acid 25.0 150.0 Sorbitan mono-oleate ('Span 80') 0.25 1.5 Emulsifying Wax ('Polawax NF') 0.5 3.0 Colloidal Silicon Dioxide ('Aerosil 200') 0.5 3.0 Sodium Metabisulphite 0.3 1.8 Disodium Edetate, dihydrate 0.1 0.6 Methylparahydroxybenzoate 0.2 1.2 Propylparahydroxybenzoate 0.04 0.24 Disodium Hydrogen Orthophosphate, 12H 2 O 1.19 7.14 Sodium Dihydrogen Orthophosphate, 2H 2 O 0.52 3.12 Glycerol 15.0 90.0 Macrogol 300 15.0 90.0 Propellants 'Arcton 12/114' 40:60 8.0 48.0 Water, Deionised 33.4 200.4 Reference EXAMPLE 3 25% 5-ASA FOAM CONCENTRATE (without Addition of Propellant) %(w/w) Weight (g) 5-Aminosalicylic Acid 25.0 250.0 Emulsifying Wax ('Polawax NF') 0.75 7.5 Sodium Metabisulphite 0.3 3.0 Disodium Edetate, dihydrate 0.1 1.0 Methylparahydroxybenzoate 0.2 2.0 Propylparahydroxybenzoate 0.04 0.4 Disodium Hydrogen Orthophosphate, 12H 2 0 1.19 11.9 Sodium Dihydrogen Orthophosphate, 2H 2 O 0.52 5.2 Water 63.9 639.0 Reference EXAMPLE 4 25% 5-ASA FOAM CONCENTRATE (without Addition of Propellant) %(w/w) Weight (g) 5-Aminosalicylic Acid 25.0 42.5 Propylene Glycol 30.0 51.0 Emulsifying Wax ('Polawax NF') 2.0 3.4 Sodium Metabisulphite 0.3 0.51 Disodium Edetate, dihydrate 0.1 0.17 Sodium Benzoate 0.1 0.17 Disodium Hydrogen Orthophosphate, 12H 2 O 1.0 1.7 Sodium Dihydrogen Orthophosphate, 2H 2 O 0.6 1.02 Water 35.95 61.115 Reference EXAMPLE 5 25% 5-ASA FOAM %(w/w) Weight (g) 5-Aminosalicylic Acid 25.0 250.0 Polysorbate 80 0.25 2.50 Emulsifying Wax ('Polawax NF') 0.5 5.0 Colloidal Silicon Dioxide ('Aerosil 200') 0.5 5.0 Sodium Metabisulphite 0.3 3.0 Disodium Edetate, dihydrate 0.1 1.0 Methylparahydroxybenzoate 0.2 2.0 Propylparahydroxybenzoate 0.04 0.4 Disodium Hydrogen Orthophosphate, 12H 2 O 1.19 11.9 Sodium Dihydrogen Orthophosphate, 2H 2 O 0.52 5.2 Glycerol 15.0 150.0 Macrogol 300 15.0 150.0 Water, Deionised 33.4 334.0 Propellants 'Arcton 12/114' 40:60 8.0 80.0 100.0 100.0 Reference EXAMPLE 6 22.5% 5-ASA FOAM %(w/w) Weight (g) 5-Aminosalicylic Acid 22.50 2.475 Polysorbate 20 (Tween 20) 10.00 1.100 Emulsifying Wax ('Polawax NF') 0.40 0.044 Colloidal Silicon Dioxide (Aerosil 200) 0.40 0.044 Sodium Metabisulphite 0.30 0.033 Disodium Edetate, dihydrate 0.10 0.011 Methylparahydroxybenzoate 0.20 0.022 Propylparahydroxybenzoate 0.04 0.0044 Disodium Hydrogen Orthophosphate, 12H 2 O 1.19 0.131 Sodium Dihydrogen Orthophosphate, 2H 2 O 0.52 0.057 Glycerol 11.50 1.265 Macrogol 300 11.50 1.265 Water, Deionised 31.35 3.44 Propellants 'Arcton 12/114' 40:60 10.00 1.100 100.00 11.00 EXAMPLE 1 20% 5-ASA FOAM %(w/w) Weight (g) 5-Aminosalicylic Acid 20.00 1.000 Sorbitan Mono-oleate 0.21 0.011 Polysorbate 20 7.80 0.390 Emulsifying Wax 0.43 0.022 Colloidal Silicon Dioxide 0.43 0.022 Sodium Metabisulphite 0.26 0.013 Disodium Edetate, dihydrate 0.10 0.005 Methylparahydroxybenzoate 0.20 0.010 Propylparahydroxybenzoate 0.04 0.002 Disodium Hydrogen Orthophosphate, 12H 2 O 1.19 0.060 Sodium Dihydrogen Orthophosphate, 2H 2 O 0.52 0.026 Glycerol 12.75 0.638 Macrogol 300 12.75 0.638 Water, Deionised 33.32 1.666 Propellants 'Arcton 12/114' 40:60 10.00 0.500 100.00 5.000

Claims: Claims for the following Contracting States : AT, BE, CH, DE, DK, FR, GB, IT, LI, LU, NL, SE A pharmaceutical composition suitable for intra-rectal administration in the form of a foam which comprises: (a) a therapeutically effective amount of 5-aminosalicylic acid present in an amount between 18 and 30% (w/w) of the composition wherein the particle size of the 5-aminosalicylic acid is such that at least 95% of the particles have an equivalent sphere diameter of less than 60µ. (b) a pharmaceutically acceptable aqueous carrier therefor present in an amount from 55 (w/w) to 65% (w/w) of the composition and which contains water in an amount from 50% (w/w) to 60% (w/w) of the carrier and a water-soluble organic polyalcohol consisting of a mixture of glycerol and a polyethylene glycol, in an amount from 40% (w/w) to 50% (w/w) of the carrier, (c) a surfactant which is a mixture of sorbitan mono-oleate and Polysorbate 20, in an amount less than 12% (w/w) of the composition, (d) emulsifying wax which comprises cetostearyl alcohol and a polyoxyethylene derivative of a fatty acid ester of sorbitan in an amount between 0.3 and 0.7% (w/w) of the composition, (e) colloidal silica in an amount corresponding to up to 1% (w/w) of the composition. and (f) a liquid or liquefied gas propellant for generating a foam, A dispensing container suitable for dispensing a foam intrarectally, comprising an aerosol container fitted with a valve adapted to dispense volumes of from approximately 2ml to approximately 5ml and containing a composition as defined in claim 1. Claims for the following Contracting States : ES, GR A process for preparing a pharmaceutical composition suitable for intra-rectal administration in the form of a foam, which comprises bringing into association (a) a therapeutically effective amount of 5-aminosalicylic acid present in an amount between 18 and 30% (w/w) of the composition wherein the particle size of the 5-aminosalicylic acid is such that at least 95% of the particles have an equivalent sphere diameter of less than 60µ. (b) a pharmaceutically acceptable aqueous carrier therefor present in an amount from 55 (w/w) to 65% (w/w) of the composition and which contains water in an amount from 50% (w/w) to 60% (w/w) of the carrier and a water-soluble organic polyalcohol consisting of a mixture of glycerol and a polyethylene glycol. in an amount from 40% (w/w) to 50% (w/w) of the carrier, (c) a surfactant which is a mixture of sorbitan mono-oleate and Polysorbate 20, in an amount less than 12% (w/w) of the composition, (d) emulsifying wax which comprises cetostearyl alcohol and a polyoxyethylene derivative of a fatty acid ester of sorbitan in an amount between 0.3 and 0.7% (w/w) of the composition, (e) colliodal silica in an amount corresponding to up to 1% (w/w) of the composition. and (f) a liquid or liquefied gas propellant for generating a foam, A process according to claim 1 wherein the composition is introduced into a dispensing container suitable for dispensing a foam intrarectally, said container comprising an aerosol container fitted with a valve adapted to dispense volumes of from approximately 2ml to approximately 5ml and containing a composition as defined in claim 1.

Inventors: HEALEY JOHN NORMAN CHARLES, WHITEMAN MARSHALL, HEALEY, JOHN NORMAN CHARLES, WHITEMAN, MARSHALL
Applicants: SMITH KLINE FRENCH LAB, SMITH KLINE & FRENCH LABORATORIES LIMITED
Application year: 1990
Main classification: A61K31
IPC codes: A61K9, A61P1, A61K31