Abstract

Controlled release dosage forms enhance the safety, efficacy, reliability, and convenience of drug therapy by controlling the rate and duration of drug release to control drug actions and to reduce the frequency of drug administration, thus encouraging patient compliance. Controlled release pharmaceuticals are designed to release drugs in vivo according to a predictable, therapeutically rational programmed rate to achieve the optimal serum-drug concentration in the minimal time. The most familiar of these systems are taken orally, but a growing number are designed for less conventional body sites such as the rectum, skin, oral cavity, nose, lungs, eyes, uterus, and vagina. The energy sources for controlled drug delivery are typically processes or properties such as biodegradation, diffusion (from matrix and membrane systems), elasticity, electricity, osmosis, pH sensitivity, and vapor pressure. Increasingly important applications of controlled release technology include patterned, targeted, triggered, and closed-loop delivery.