Techniques for measuring in vitro release from semisolids

Abstract

The SUPAC-SS guidance, which governs sca/e-up and post-approval changes for sent isolids, requires in vitro release da tit in certain instances of change in the amount of an excipient, batch size or manufacturing equipment, process or site. 1'he kinetics of diffusion of an active ingredient through a semisolid into a liquid sink (the receptor) are measured: an inert, porous membrane physically separates the tiro phases. Several commercial instruments, some of which incorporate automated transfer to an analytical instrument, are available. The principal experimental decisions involve selection of temperature, membrane, receptor and timing of samples. These should be chosen to minimize undesired interactions and make diffusion through the semisolid rate-limiting so that the intrinsic release is measured. Data treatment involves plotting the amount released against the square root of time and using the slope of the linear plot as an index. Release profiles may be altered by certain changes in manufacturing or formulation.