冬凌草甲素自微乳给药系统的体外释放动力学研究

Release kinetics of oridonin self-microemulsifying drug delivery system in vitro

目的：研究冬凌草甲素自微乳给药系统的体外释放特性，探讨释药机制。方法：利用HPLC测定冬凌草甲素的含量，以反向透析法进行冬凌草甲素自微乳的体外释放实验，考察释放介质、搅拌速度和处方因素对药物释放的影响。采用相似因子法比较释药曲线的相似性，利用药物释放模型方程拟合释放曲线。结果：释放介质对药物释放无显著影响；在50～100r·min^-1药物释放曲线具有相似性；冬凌草甲素自微乳与乙醇溶液的释放曲线相似；冬凌草甲素自微乳在pH7．8PBS中，30min释放达65％，释放曲线符合Hixson—Crowell方程。结论：冬凌草甲素自微乳释药较快，在水性环境中自发形成的微小乳滴在释药过程中粒径和表面积均发生改变，药物分子透膜为被动扩散过程。

Objective： To investigate the release characteristics and mechanism of oridnonin self-microemulsifying drug delivery system （SMEDDS） in vitro. Method： The concentration of oridonin was determined by HPLC. In vitro release studies were conducted by reverse dialysis technique. The effects of release medium, agitation rate and preparations on the oridonin release were studied. The similarity factor （f2） was applied to the release profile comparisons. Model fitting was used to determine the kinetics and mechanism. Result： The release media and agitation rate from 50-100 r · min^-1 had no distinctive effect on the oridonin release kinetics, which the similarity factors were greater than 50.. The oridonin release profdes for oridonin SMEDDS and oridonin ethanol solution were similar. 65% of oridonin were released in 30 rnin for oridonin SMEDDS in pH 7.8 PBS. Oridonin SMEDDS fit the Hixson-Crowelt model best. Conclusion： The release data from oridonin SMEDDS showed it release fast. The deduced release mechanism is that the surface and particle sizes of seff-microemulsion in water solution are changing during the process of release and the drug penetration through membrane is a passive diffusion process.