EP0111144A1 — Sustained release solid dosage forms having non-uniform distribution of active ingredient

USPTO Abstract

This invention relates to sustained-release, solid-dosage forms having non-uniform distribution of active ingredient which provides for zero-order release of the active ingredient. The non-uniform distribution Is accomplished by providing for a multitude of enveloping, concentric layers over a central core. Each of the various layers having constant concentration of a hydrophilic gel and each layer and the core having an amount of medicament defined by the expression wherein D L is the amount of medicament in the core or in any given sustained-release layer, D T is the total amount of medicament in the sustained-release portion of the tablet, R D is the differential radius for the core or the enveloping layer for which the amount of required medicament is to be determined and R T is the radius of the sustained-release portion of the tablet.