Drug-Coupled Poly(Amino Acids) as Polymeric Prodrugs

Biodegradable poly(alpha-amino acids) can serve as chemical carriers of active agents. The narcotic antagonist naltrexone and the anti-hypertensive minoxidil were covalently coupled to polymer backbones based upon L-glutamic acid to give polymeric prodrugs. The synthesis and release characteristics of these two systems are reviewed. The rate of hydrolytic cleavage of the polymer-drug linkage should be much slower than the rate of diffusion through the polymer matrix; thus release rates approaching zero order can be achieved. In vitro and in vivo release studies demonstrate the potential for these types of polymeric delivery systems.