Novel burst-free, sustained release biocompatible and biodegrable microcapsules
which can be programmed to release their active core for variable durations ranging
from 1-100 days in an aqueous physiological environment. The microcapsules are
comprised of a core of polypeptide or other biologically active agent encapsulated
in a matrix of poly(lactide/glycolide) copolymer having a molar composition of
lactide/glycolide from 90/10 to 40/60, which may contain a pharmaceutically-acceptable
adjuvant, as a blend of uncapped free carboxyl end group and end-capped forms ranging
to ratios from 100/0 to 1/99.
