| abstract |
The invention relates to a device for the release of at least one active substance (e.g. ranitidine) into a fluid medium by dissolution comprising a covering, which is impermeable to the active substance and the fluid, having at least one aperture therein and defining a shaped cavity, the cavity being filled by a shaped core comprising the active substance, and wherein:n a) on exposure of the device to the fluid medium, a surface of the core is exposed and dissolution of the surface by the fluid medium causes a change in at least one dimension of the area of the surface, whilst the surface area of the exposed surface remains substantially constant over at least 50% of the total dissolution time of the core; or b) the active substance is disposed in a matrix of an inert insoluble excipient, the device being axially symmetrical, with its aperture being peripherally disposed so that the release surface of core which is exposed through the aperture is substantially cylindrical or part of a cylinder in shape, whereby to allow substantially constant release of the active substance over at least part of the dissolution time; and processes for its preparation. |