Abstract: Poly(lactic-co-glycolic acid) (PLGA) microspheres were prepared by premix membrane emulsification. The final optimum conditions for their particle size and size distribution were obtained: transmembrane pressure 5 kPa, concentration of poly(vinyl alcohol) in water phase 19 g/L and volume ratio of oil phase to water phase 1:10. The mean particle size of microspheres prepared under the optimal conditions was about 24 mm with Span value below 0.7. Furthermore, growth hormone-releasing peptide-6 loaded PLGA microspheres were prepared. The encapsulation efficiency of GHRP-6 loaded microspheres reached 85% under the concentration of Arlacel 83 2.5 g/L and concentration of NaCl in external water phase 10 g/L. Primary emulsion method had significant effect on both encapsulation efficiency and in vitro release profile. The microspheres prepared by ultrasonication showed compact interior structure with high encapsulation efficiency but slow as well as incomplete drug release; in comparison, the microspheres prepared by homogenization exhibited loose structure with decreased encapsulation efficiency and constant drug release.

Key words: premix membrane emulsification, poly(lactic-co-glycolic acid) microspheres, uniform-sized, growth hormone-releasing peptide-6, primary emulsion method

摘要： 采用快速膜乳化法制备了聚(乳酸-羟基乙酸)(PLGA)微球，得到制备PLGA微球的优化条件为：过膜压力5 kPa，水相中PVA浓度19 g/L，油/水相体积比1:10，该条件下所制空白微球的平均粒径约为24 mm，粒径分布系数Span<0.7. 在此基础上制备载生长激素释放肽-6(GHRP-6)微球，油相乳化剂浓度2.5 g/L、外水相中NaCl浓度10 g/L条件下所制载GHRP-6微球包埋率最高可达85%，初乳制备方式对药物包埋率及体外释放行为均有较大影响，超声法制备的初乳所得微球内部结构紧密，药物包埋率较高(85%)，但释药缓慢；而均质法制备的初乳所得微球内部结构疏松，药物包埋率较低(76.8%)，但在体外释放更完全.

关键词: 快速膜乳化, 聚(乳酸-羟基乙酸)微球, 粒径均一, 生长激素释放肽-6, 初乳制备方式