Drug release from PLA/PEG microparticulates

Drug-loaded biodegradable PLA, PLA/PEG microspheres were prepared by the coacervation technique, by solvent evaporation and by the emulsion method. The effects of drug properties, particle size, drug loading and method of microencapsulation on the in vitro drug dissolution were also examined. According to the results, PLA/PEG copolymer was more hydrophilic than PLA homopolymer, and with lower glass transition temperature. PLA/PEG microparticulates were not as smooth as that of PLA. Drug release from microspheres was effected by the properties of PLA/PEG copolymers. The release rate of the hydrophobic drug, lidocaine, encapsulated in the polymer PLA/PEG copolymer, was faster than that in a pure PLA homopolymer. The same results also held for the hydrophilic drug, propranolol hydrochloride. Microspheres obtained by the emulsion method were porous and with adequate drug permeability. (C) 1997 Elsevier Science B.V.