Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Capsules
Patent
1987-09-23
1989-07-11
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Capsules
424 45, 424 46, 424426, A61K 966
Patent
active
048470910
DESCRIPTION:
BRIEF SUMMARY
This invention relates to pharmaceutical compositions.
Sodium cromoglycate has been known for a number of years for the treatment of allergic conditions, for example asthma, hay fever, vernal keratoconjunctivitis and rhinitis; however it suffers from the disadvantage that it is of relatively short duration of action.
Microspheres have been proposed as drug delivery systems for numerous therapeutic areas including oral delivery of tetracycline, oral and intramuscular delivery of insulin for treatment of diabetes, subcutaneous delivery of local anaesthetics, delivery of cytostatics to various organs and intra-arterial coadministration with cytostatics, and as local dosage forms for e.g. ophthalmic, intra-articular, intramuscular, percutaneous, subcutaneous and nasal use.
Known microsphere formulations of sodium cromoglycate, however, suffer from the disadvantage that release of drug from the microspheres is very rapid, leading to a short duration of action and a requirement for frequent application.
We have now found a pharmaceutical microsphere formulation of sodium cromoglycate which substantially overcomes or mitigates these disadvantages.
Thus, according to the invention there is provided a pharmaceutical composition comprising microspheres incorporating sodium cromoglycate, wherein the microspheres include material having ion-exchange properties.
The microspheres are preferably formed from biodegradable material. The material should be compatible with sodium cromoglycate. Suitable biodegradable materials which have ion-exchange properties include suitable modified polymeric carbohydrates, e.g. diethylaminoethyl dextran. Alternatively the microspheres may comprise, as a first component, a biodegradable polymeric material not having ion-exchange properties and, as a second component, a biodegradable polymeric material having ion-exchange properties. The weight ratio of first component to second component is preferably from about 1:1 to 50:1, more preferably from about 1:1 to 25:1. Suitable biodegradable materials not having ion-exchange properties include carbohydrates e.g. starch and dextran; modified carbohydrates such as dextran cross-linked with epichlorhydrin e.g. the material known as dextranomer; serum albumin, e.g. rabbit, bovine or human serum albumin; gelatin; polyacrylamide and polycyanoacrylate; polyacryldextran and polyalkylcyanoacrylate. Polymeric materials which have ion-exchange properties include suitable modified carbohydrates e.g. diethylaminoethyl dextran.
The microspheres according to the invention may be prepared by procedures known in the art. In general microspheres including sodium cromoglycate may be prepared either by emulsifying aqueous solutions of microsphere material, e.g. diethylaminoethyl dextran, and sodium cromoglycate in a non-aqueous medium, e.g. olive oil or cotton seed oil, or by soaking preformed microspheres in a solution of sodium cromoglycate. In the former method of preparation of microspheres, a cross-linking agent may also be included in the aqueous solution. In either case, the microspheres may be removed by filtration, washed, e.g. with ether, and freeze dried.
The preferred size of the microspheres depends on the material used for the microsphere, the target organ(s), the disease being treated and the mode of administration.
In general, we prefer microspheres with a mean diameter between 1 .mu.m and 200 .mu.m. Microspheres for administration to the lung, e.g. as an entrained aerosol powder or as a pressurised aerosol, preferably have a mean diameter from 1 to 10 .mu.m, more preferably 3 to 8 .mu.m. For administration to the nose as an insufflated powder, the microspheres preferably have a mean diameter of from 5 to 200 .mu.m, more preferably 75 to 100 .mu.m. Microspheres for administration to the nose as a pressurised aerosol preferably have a mean diameter of from 1 to 10 .mu.m, more preferably 3 to 8 .mu.m. Microspheres may also be applied to the eye, e.g. as a suspension, and preferably have a mean diameter less than 30 .mu.m, e.g. 10 to 25 .mu.m. Micros
REFERENCES:
patent: 3425962 (1969-02-01), Granatek et al.
patent: 4057556 (1977-11-01), Bagli
patent: 4221778 (1980-09-01), Raghunathan
Fisons plc
Page Thurman K.
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