论文部分内容阅读
Objective: Preparation and evaluationof long acting levonorgestrel(LNG)-loaded biodegrable microspheresfor contraception by the O/W type emulsion-solvent evaporation process.Methods:LNG-loaded microspheres were preparedby using PLGA and PLA, two kinds of polyester, as the combined matrix.LNG andpolymers were dissolved in the organic solvent (dichloromethane,DCM), and polyvinyl alcohol (PVA) solution was used as the water phase in the emulsification process.We also used N-methyl-2-pyrrolidone (NMP) as the co-solvent.Thetype of organic solvent and emulsifying O/W ratio were investigated (Table 1).LNG-loaded microspheres was characterized.The water bath shaker was used in the in vitrorelease test, and we detected the residual amount of LNG in microspheres at the injection sites of rats to help measuring the in vivo release.Results:The three batches formulations showed a good EE about 70%.The drug loading and yield of batch no.3 were higher than others.The in vitro initial burst releaseof batch no.3 was 48.17%, while the in vivo release test showed an initial burst release of 13.97% and the LNG release after 28d amounted to about 50%(Fig.1).Conclusion:According to the results, the formulation use NMP as the co-solventwas better than others, and worthy of further investigation.