Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Tablets – lozenges – or pills
Patent
1997-04-22
1998-10-20
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Tablets, lozenges, or pills
424489, 424472, A61K 922
Patent
active
058243410
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/FR95/01079 filed Aug. 11, 1995.
FIELD OF THE INVENTION
The present invention provides a composition that ensures selective release of an active ingredient at a given site, and in particular a pharmaceutical composition enabling selective release of an active ingredient to be obtained at a target organ. The present invention more particularly relates to a pharmaceutical composition intended for oral administration, providing selective release of its active ingredient in the colon.
BACKGROUND OF THE INVENTION
Numerous pharmaceutical compositions have been developed with an aim to providing controlled release of the active ingredient. The majority of these compositions are based on the principle of delayed release or sustained release of the medicament at, or not at, a target organ.
EP-A-0,250,374 discloses coated mini-dosing units. Their core is obtained by compressing a mixture of the active ingredient with polymers that swell in water by osmosis action, the polymeric coating that surrounds the core controlling release of the medicament.
EP-A-0,077,956 discloses enteric micro-capsules containing an active compound as a core material, surrounded by a coating essentially consisting of ethyl cellulose and an enteric polymer material, a water-swellable polymer material being optionally incorporated into the core.
GB-A-2,202,143 discloses a pharmaceutical composition comprising a water-insoluble drug dispersed in a matrix consisting of microcrystalline cellulose and at least one cellulose derivative. Such a composition leads to sustained release of the active compound over a period of at least 8 hours. These compositions can be coated with an enteric coating so as to ensure release of the medicament in the intestinal tract rather than in the stomach.
The dosing units described in these documents do not make it possible to obtain immediate release of the active ingredient at a precise organ; speed of release is limited by the speed of diffusion through the matrix surrounding or trapping it, the result of this possibly being that all the administered dose is not released at the target organ. Effectively, considering the gastro-intestinal tract, transit time varies from one individual to another over a wide range, and the conditions prevailing in the gastro-intestinal system, notably as regards pH, also vary over wide degrees.
Research carried out with a view to obtaining a composition providing selective release of active ingredients at a target organ (for example the colon) were up until now centered around either the use of tablets for oral administration, coated with polymers that become decomposed by the bacteria present in the colon, or the use of tablets for oral administration, that were coated with an enteric coating.
In the first type of approach, the pro-drug concept is used, in other words a precursor of the active ingredient, the active ingredient being bound to, for example, a glucoside type polymer (Friend, Phillips et Torzen, F. Controlled Rel., 15, 47-54, (1991)). The main problem with this approach is that the medicament itself is chemically modified, and release of the active ingredient is conditioned by in-situ bacterial hydrolysis.
In the second type of approach, coatings are used consisting of polymers the solubility of which depends on pH, and which dissolve at a pH above that of the stomach. The products are unable to dissolve until the pH value of the ambient medium is above a certain value.
The use of tablets having this type of coating does not lead to satisfactory results and does not make it possible to obtain targeted release of active ingredients. In effect, if the pH profile of the gastro-intestinal tract is studied, it is noted that the pH in the distal part of the intestine varies between 6.8 and 7.2, and then falls to a value of 4.5 to 6 in the ascending colon. Consequently, the pharmaceutical composition is designed whereby the polymer coating dissolves at a pH which is greater than or equal to 7; the polymer dissolves in the intestine and t
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Seth Pawan
Stamm Andre
Page Thurman K.
Pharma Pass
Shelborne Kathryne E.
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