This presentation discusses kinetics of drug release from controlled release drug delivery systems. It begins by describing different types of controlled release systems including matrix systems, encapsulation systems, and reservoir systems. It then discusses the mechanisms of drug release, focusing on diffusion processes. Mathematical models for drug release are presented, including Higuchi's equation and Fick's laws of diffusion. Factors that influence drug diffusion and release rates are also summarized such as temperature, molecular weight, particle size, and drug solubility.