夫西地酸微乳凝胶的制备与体外抗菌活性研究

Preparation and in vitro antibacterial activity evaluation of fusidic acid microemulsion gels

目的 制备夫西地酸微乳凝胶并评价其体外抗菌活性。方法 通过考察夫西地酸在不同油相、表面活性剂和助表面活性剂中的平衡溶解度,确定夫西地酸微乳的处方组成,并进一步通过伪三元相图获得其处方用量;以卡波姆941作为凝胶基质制备夫西地酸微乳凝胶。使用激光粒度仪在25℃测定微乳的粒径分布以及Zeta电位;透射电子显微镜下观察微乳的形貌;使用黏度计和pH计在25℃测定微乳凝胶的黏度及pH值;透析法测定夫西地酸微乳和夫西地酸微乳凝胶的体外药物溶出速率;以外观、黏度和pH值作为指标,考察夫西地酸微乳凝胶在4、25℃下3个月内的物理稳定性;Mueller-Hinton肉汤稀释法测定夫西地酸微乳凝胶和夫西地酸原料药对金黄色葡萄球菌的最小抑菌浓度(MIC);通过抑菌圈实验比较夫西地酸原料药和夫西地酸微乳凝胶的体外抗菌活性。结果 根据各辅料对夫西地酸溶解性,选择油酸乙酯、聚山梨酯80和异丙醇分别作为夫西地酸微乳的油相、表面活性剂和助表面活性剂,配比为6∶2∶2;夫西地酸微乳外观为淡蓝色半透明状溶液,在透射电镜下可观察到其呈规则球型,粒径分布均匀,平均粒径为(105.4±2.9)nm,Zeta电位为(-16.9±0.6)mV;夫西地酸微乳的黏度为(0.027 7±0.000 5)Pa·s,黏度过低,而夫西地酸微乳凝胶的黏度为(5.614 5±0.036 1)Pa·s;夫西地酸微乳中的药物在15 min内已完全溶出,而夫西地酸微乳凝胶中的药物溶出速度明显减慢,在240 min时溶出达到90%左右;夫西地酸微乳凝胶3个月内物理性质稳定。夫西地酸微乳凝胶、原料药对金黄色葡萄球菌的MIC分别为0.12、0.40μg·mL^(-1),抑菌圈直径分别为(33.7±0.6)、(27.5±0.7)mm。结论 制备的夫西地酸微乳凝胶理化性质较好,体外抗菌活性显著,有潜力成为夫西地酸局部外用给药新剂型。

Objective To prepare fusidic acid microemulsion gels and evaluate its in vitro antibacterial activity. Methods By evaluating the balance solubility of fusidic acid in different oils, surfactants and co-surfactant, the formulation composition of fusidic acid microemulsion was determined, and its formulation dosage was further obtained by pseudo-ternary phase diagram. The fusidic acid microemulsion gels were prepared with Carbomer 941 as a matrix. The particle size distribution and Zeta potential of microemulsion were measured by laser particle size analyzer at 25 ℃. The morphology of microemulsion was observed under transmission electron microscope. The viscosity and pH values of the microemulsion gel were measured at 25 ℃ using a viscosity meter and a pH meter. The dissolution rate of fusidic acid microemulsion and fusidic acid microemulsion gel in vitro was determined by dialysis method. The physical stability of fusidic acid microemulsion gel at 4 ℃ and 25 ℃ for three months was investigated with the appearance, viscosity and pH values as indexes. The minimum inhibitory concentration(MIC) of fusidic acid microemulsion gel and fusidic acid API against Staphylococcus aureus was determined by Mueller-Hinton broth dilution method. The antibacterial activity of fusidic acid API and fusidic acid microemulsion gel in vitro was compared by bacteriostatic zone assay. Results According to the solubility of fusidic acid in various excipients, the ethyl oleate, Tween 80 and isopropyl alcohol were selected as oil phase, surfactant and co-surfactant of fusidic acid microemulsion, respectively, and the formulation ratio was 6:2:2. The fusidic acid microemulsion was spherical and its particle size distribution was uniform under the transmission electron microscope, the average particle size was(105.4±2.9) nm and Zeta potential was(-16.9±0.6) mV. The viscosity of fusidic acid microemulsion was(0.027 7±0.000 5) Pa·s, which was too low, while the viscosity of fusidic acid microemulsion was(5.614 5±0.036 1) Pa·s. The drugs in fusidic acid microemulsion were completely dissolved within 15 min, while the dissolution rate of drugs in fusidic acid microemulsion gel was significantly slowed down, reaching about 90% at 240 min. The physical properties of fusidic acid microemulsion gel were stable within three months. The MIC of fusidic acid microemulsion gel and API against S. aureus were 0.12 and 0.40 μg·mL^(-1),respectively, and the diameters of inhibition zones were(33.7±0.6) and(27.5±0.7) mm, respectively. Conclusion Fusidic acid was prepared into microemulsion gels, the physicochemical properties were good, the in vitro antibacterial activity was significant. It was expected to be a novel vehicle for the topical use of fusidic acid.