ABSTRACT
Sustained and/or controlled release of biological agents is a concept that has received a great deal of attention during the past decade. Systems designed to release drugs at a rate directly influenced by the nature of their surrounding environment will be referred to as sustained delivery devices. Drug delivery devices designed to release drug at a predetermined rate influenced to a large extent by the nature of their fabrication, and not to a significant extent by environmental interaction, will be referred to as controlled delivery systems. The primary goal of sustained or controlled drug release is the prolonged delivery of a drug to a particular body compartment or anatomical target site. For many drug systems, the parent drug may be the only active drug species and consideration of individual drug metabolites within the kinetic model may not be of significant clinical importance.
