Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Tablets – lozenges – or pills
Patent
1996-11-25
2000-10-24
Webman, Edward J.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Tablets, lozenges, or pills
424474, A61K 924
Patent
active
061363456
DESCRIPTION:
BRIEF SUMMARY
This invention relates to tablet formulations for oral administration, particularly to formulations, which comprise a .beta.-lactam antibiotic, optionally together with a .beta.-actamase inhibitor.
Many known tablet formulations which include .beta.-lactam antibiotic are required to be taken orally three times a day. There is a need for oral formulations which need only be taken twice or less often per day. Methods of forming delayed or sustained release tablet formulations are known, for example coating the tablet with a release-retarding coating, or coating individual granules with such a coating, and compressing these coated granules into a tablet. "Release-retarding" as used herein, unless otherwise defined, refers both to release which is retarded so as to be sustained, i.e. active material is released gradually from the tablet, and to release which is retarded so as to be delayed, i.e. release begins or the rate of release increases after an initial delay.
Particular problems occur in the preparation of delayed or sustained release forms of the known antibacterial combination of the .beta.-lactam antibiotic amoxycillin, in the form of its trihydrate, and the .beta.-lactamase inhibitor clavulanic acid, in the form of an alkali metal salt, such as potassium clavilanate. This is because amoxycillin trihydrate is relatively insoluble in aqueous media, whereas potassium clavulanate is extremely soluble, hygroscopic and moisture-sensitive, and it is difficult to achieve sustained or delayed release of two such components at a compatible rate from a single formulation containing both.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 shows a cross-section through the tablet of the invention.
According to this invention, a tablet formulation comprises a core which includes a first pharmaceutically active material, the core being coated with a release retarding coating, the coated core being itself surrounded by a casing layer which includes a second pharmaceutically active material.
The tablet formulation of the invention is suitable for oral administration, and provides a sustained and/or delayed release as a result of initial quick release of the second active material from the casing layer, and a sustained or delayed release of first active material from the coated core. Also the casing layer may serve to protect the core from the ingress of air and atmospheric moisture. Also coating of a single relatively large core in the tablet of the invention with a release-retarding coating requires less coating material than is required to coat a large number of smaller granules, and can therefore lead to a relatively low tablet weight.
The first and second pharmaceutically active materials in the tablet formulation may each individually, and/or together, comprise a .beta.-lactam antibiotic optionally together with a .beta.-lactamase inhibitor. Suitably the .beta.-lactam antibiotic may be amoxycillin, e.g. in the form of its trihydrate, optionally together in combination with the .beta.-lactamase inhibitor clavulanate, (the term "clavulanate" used herein, unless otherwise identified, refers both to clavulanic acid and its salts) e.g. in particular potassium clavulanate. The first and second active materials may both comprise the same active material, for example both comprising a .beta.-lactam antibiotic optionally in combination with a .beta.-lactamase inhibitor. When both the first and second active materials comprise amoxycillin and clavulanate, the relative ratios of amoxycillin: clavulanate may be different in the core and the casing layer, making up the overall ratio in the tablet.
The amoxycillin: clavulanate ratios in the core and casing layer and the overall ratio may each vary between broad limits, e.g. between 30:1 to 1:1, typically 12:1 to 2:1. A preferred ratio is around 8:1 to 4:1.+-.25%.
The quantity of active material(s) in the tablet may vary up to the maximum allowed daily dose, and may typically be around a nominal single unit dose. For example in the case of amoxycillin and clavulanate, a single tablet
REFERENCES:
patent: 3279997 (1966-10-01), Schneyer
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patent: 5277916 (1994-01-01), Dwyer et al.
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patent: 5558879 (1996-09-01), Chen et al.
Davidson Nigel Philip McCreath
Grimmett Francis Walter
Kinzig Charles M.
SmithKline Beecham p.l.c.
Webman Edward J.
Williams Janice E.
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