Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Matrices
Patent
1995-02-15
1997-05-13
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Matrices
424489, 424468, 424469, 424470, 514778, 514965, A61K 916
Patent
active
056290187
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a composition for delayed release of an active substance in a target environment, the active substance being incorporated in a polysaccharide matrix.
2. Description of the Related Art
Compositions for delayed release of an active substance, for example for delayed release of an enzyme for oral administration in the gastrointestinal tract of a mammal, have advantages, inter alia because the administration of the active substance can take place in a small number of doses and because a more constant concentration is obtained in the target environment.
Compositions for delayed release are known in diverse forms. One form of delayed release can comprise the presence of a matrix containing the active substance therein, which matrix slowly dissolves in the aqueous environment and thus releases the active substance in a delayed manner; a composition of this type is, for example, disclosed in European Patent Application EP-A-241179. A composition of this type in which the matrix is formed by a natural polysaccharide such as xanthan is disclosed in International Patent Application WO-A-87,05212. According to a variant thereof, the active substance is packaged in an insoluble capsule which is provided with a water-soluble stopper, as disclosed, inter alia, in British Patent Application 2,241,485.
Another form of a composition for delayed release is a composition from which the active substance is released by erosion, as is disclosed, for example, in European Patent Application EP-A-381182.
Compositions for delayed release in which the matrix material is a .beta.-glucan, such as cellulose or a cellulose derivative, are disclosed, inter alia, in International Patent Application WO-A-88,10284 and Netherlands Patent Application 87,02294 (=GB-A-2,195,893). The use of heat-modified starch as the matrix for the controlled release of medicaments for oral administration is described by J. Herman and J. P. Remon, Int. J. Pharmaceutics, 56, 51-63 and 65-70 (1989).
The known compositions for the delayed release of an active substance frequently have the disadvantage that release is possible only for substances dissolving in the environment or effectively diffusing through the matrix material. Furthermore, the active substance of the known compositions does not normally proceed in accordance with an ideal zero order rate, that is to say with a constant amount per unit time, but in accordance with a first order rate, that is to say with an amount which decreases per unit time, or poorer; in addition, the materials used as matrix are often expensive.
SUMMARY OF THE INVENTION
The object of the invention is to provide a composition, and a method for the preparation thereof, which releases an active substance in a delayed manner and within a predetermined period of time, which further is harmless to health and/or the environment and which, moreover, is economical in use. The composition should especially be suitable for delayed release of active substances having a high molecular weight, which moreover are sensitive under certain conditions, such as a low pH or at increased environment temperatures.
This object is achieved by means of a composition according to the invention which to this end is characterised in that the matrix material in which the active substance is incorporated comprises an essentially crystalline straight-chain glucan and a glucan-degrading agent. The glucan is preferably an .alpha.-glucan and in particular an .alpha.-1,4-glucan and preferably has essentially a helical structure.
An .alpha.-1,4-glucan is understood to be an essentially straight-chain polysaccharide which is composed of anhydroglucose units which are linked to one another by .alpha.-bridges via the 1-position and 4-position. Other straight-chain glucans (polysaccharides) can also be used if these are able to assume a spiral-like structure, such as, for example, .beta.-1,3-glucans.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Suitable .alpha.-1,4-glucans are i
REFERENCES:
patent: 3493652 (1970-02-01), Hartman
Besemer Arie C.
Van Der Lugt Jan P.
Nederlandse Organisatie voor Toegepast-Natuurwetenschappelijk On
Page Thurman K.
Spear James M.
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