Preparation and evaluation in vitro of polylactic acid microspheres containing local anesthetics.

Abstract

The use of DL-polylactic acid (PLA) microspheres as a means to achieve sustained release of butamben, tetracaine, and dibucaine was examined in vitro. As a first step, PLA solutions in an organic solvent containing the drug were dispersed in viscous aqueous solutions, then microspheres were formed by a solvent-evaporation process. The release mechanism was examined by scanning electron microscopy. The effects of polymer solvents and nonsolvents on the microsphere characteristics and release patterns from the microspheres were examined. The effects of drug contents and microsphere size on release patterns were also investigated.