Preparation and in vitro release properties of lovastatin-polylactic acid microspheres

Lovastatin-polylactic acid(PLA) microspheres have been prepared using a solvent evaporation-extraction method.The synthesis process was optimized using orthogonal tests and the factors that influence the process were analyzed.The surface morphology and average diameter of the microspheres were characterized by scanning electron microscopy,and the drug-loading ratio and encapsulation ratio were calculated.The dialysis method was used to study the drug release properties.Microspheres prepared by the optimized process were round with smooth surfaces.For microspheres made of PLA(50000),the average diameter was 65.8μm,the drug-loading-ratio was 32.28%,and the encapsulation ratio was 81.81%.For microspheres made of PLA(30000),the average diameter was 63.3μm,the drug-loading ratio was 27.66% and the encapsulation ratio was 60.84%.After 10days at 37℃,the in vitro cumulative release ratios for the two materials were 40.96% and 34.81%,respectively.The release profiles could be fitted to the Higuchi equation.