Controlled release: mechanisms and release.

Abstract

Controlled-release systems of drug administration are discussed with an explanation of how the controlled release of agents according to zero-order of 1st-order kinetics (or other patterns) arises from membrane-moderated devices and the application of diffusion laws. Parameters which determine the release rate are discussed and it is shown how the release rate changes with alterations in these parameters. 2 types of membrane-moderated controlled-release devices are described: 1) those which are composed of a core of active agent surrounded by an inert diffusion barrier and 2) those in which the active agent is dissolved or dispersed in the diffusion barrier.