Effects of membrane type and liquid/liquid phase boundary on in vitro release of ketoprofen from gel formulations.

The aim of this study was to test the hypothesis that the most appropriate model for studying the diffusional release of an active from a topical formulation is one in which the membrane offers minimal resistance to release and involves a receptor phase that presents the least possible interfacial discontinuity. Using ketoprofen as the active, a series of simple gels were prepared consisting of PEG400 thickened with Cabosil M5. Using Franz-type diffusion cells, three different types of membrane (two porous and one non-porous) were compared, as were receptor phases of PEG400 (component of formulation) and PBS.