DESIGN OF BIODEGRADABLE POLYMER SYSTEMS FOR CONTROLLED-RELEASE OF BIOACTIVE AGENTS

Major advances in therapeutic regimens are now possible with biodegradable polymer systems for controlled delivery of bioactive agents. Therapies involving peptide and protein drugs will be most applicable in the future; however, these types of therapies are limited in use due to their low oral absorption potential and relatively short half-lives. Parenteral (subcutaneous or intramuscular) administration of a ''depot'' preparation of a peptide/protein drug in a controlled release polymer matrix can provide very effective continuous therapy. Many of these delivery systems use microspheres composed of biodegradable homo- and copolymers of lactic and glycolic acid. Extensive experience with these materials has established their safety, biocompatibility, and subsequent biodegradation to non-toxic products. Short-term therapeutic regimens can be designed based on the selection and optimization of a number of drug/polymer variables. This paper examines the technology involved in the design of a controlled release injectable product for peptides and proteins, with particular emphasis on the pharmaceutical aspects of quality control and regulatory compliance.