Influence of physicochemical properties of polylactic acid on the characteristics and in vitro release patterns of polylactic acid microspheres containing local anesthetics.

Abstract

DL-Polylactic acid (PLA) microspheres were prepared from 3 lots of PLA by a solvent-evaporation process, and release patterns of butamben, tetracaine and dibucaine from these microspheres were examined. As a 1st step, the physicochemical characteristics of 3 lots of PLA were examined. The release mechanism was examined by scanning electron microscopy. Microsphere characteristics and release patterns from the microspheres were dependent on both PLA characteristics and the local anesthetics used for the preparations.