COIft'lOLLID ULIlSI or PROTII. lID DCCIHS ROll POLY(ISTIIt) IICROSPBlUS IN VI2'RO H.T. Vang, B. Palmer, I.J. Linhardt., D.I. Flanagan and E. Schaitt Division of Medicinal and Natural Products Chemistry and Division of Pharmaceutics College of Pharaacy University of Iowa Iowa City, Iowa 52242 Biodegradable aicrospheres of po1y(L-1actide) and copoly- mers of lactide and glycolide have been prepared by spray drying. Degradation studies of these microspheres using resi- dual mass measurements, viscometry and gel permeation chroma- tography indicated the entire mass of polyester matrices was aaintained for 10, 30 days and 6-10 months for 50:50 and 85:15 copolymers and poly(L-1actide), respectively. The con- tinuous drop in polymer intrinsic viscosity and molecular weight during hydrolysis suggested that matrix degradation began as soon as these microspheres were placed in the buffer and that their degradation proceeded through random-chain scission. Protein release, using bovine serum albumin micro- spheres, showed that release from 50:50 copolymer was inde- pendent of polymer molecular weight over a range from 31,000 to 93,000. The release was, however, dependent on the polymer coaposition and BSA loading in the microspheres. A burst- effect was found in the release study for microspheres pared from copolymers. The identity and integrity of the released protein was confirmed by sodium dodecy1 sulfate polyacrylamide gel electrophoresis on the release products of polymeric microspheres containing BSA, FPL-K and EcoBac R-P1us vaccines. These results suggested that the release BSA (or vaccine) from polymeric aicrospheres could be sustained for up to one month. III'ftODUCTIOI Biodegradable polymers have been used in delivery of drugs l-9 and bio1ogicals. 1o - 11 The major advantages of biodegradable polymers used in controlled release applications are that they do not require surgical removal from the host after delivery of bioactive agent is complete. Additionally, adverse tissue reactions from implanted polymer may be ame1iorated. 1t - 20 Cosmetic and PhDrflllJCeMlico1 Applicalions of Polymers Edited by C.G. Gebelein et 01., Plenwn Press, New York, 1991 239