Biodegradable polymers for protein and peptide drug delivery.

We have reviewed a large cross-section of degradable polymeric delivery systems for protein and peptide pharmaceuticals. These systems include monolithic type devices in which the drug is dispersed throughout the polymer and protein-polymer conjugates where the drug is covalently bound to the polymer. These delivery systems have unique challenges associated with their development that are related to both protein stability and protein release kinetics. Despite numerous reports in the scientific literature which include many encouraging results in preclinical models, very few of these systems have been developed into viable products. The products that have made it to market, however, have proven to be very successful and demonstrate the significant advantages that these systems can provide. The continuous advances in biotechnology will produce more proteins and peptides that will be difficult to administer by conventional means, and an increased demand for controlled or site-specific delivery systems is anticipated.