Preparation of pingyangmycin PLGA microspheres and related in vitro/in vivo studies

Using a multiple emulsion solvent evaporation method, pingyangmycin was entrapped in poly(lactic-co-glycolic acid) (PLGA) to prepare a long-acting pingyangmycin PLGA microsphere formulation that can be sustainably released with high entrapment efficiency. Meanwhile, the effects of stirring speed during the multiple emulsion solvent evaporation process were also taken into consideration. Investigation of the in vitro release properties showed that the microsphere formulations could sustainably release the drug over nearly 28 d, and, moreover, it could stably control pingyangmycin release over nearly 24 d when intramuscularly injected into dogs. No serious toxic effect was observed in an acute toxicity test in mice. A subcutaneous xenotransplant model of hepatoma H22 in mice was established for pharmacodynamic studies and the results showed that the process of preparing pingyangmycin PLGA microsphere formulations was feasible and that intramuscular injection of this microsphere formulation resulted in anti-tumor activity in vivo.