黄芩苷微乳凝胶的稳定性和流变学考察

Stability and Rheological Characteristics of Baicalin Loaded in Microemulsion-based Gel

关键词:  黄芩苷  微乳凝胶  初步稳定性  影响因素试验  流变学

Key words:  baicalin  microemulsion gel  preliminary stability  influencing factor test  rheology

摘要:

目的 研究黄芩苷微乳凝胶（baicalin loaded in microemulsion-based gel，B-MBG）的稳定性和流变学。方法 通过初步稳定性试验，对B-MBG的外观性状、微观形貌、pH、黏度、含量和粒度等方面进行考察；通过流变学试验对B-MBG的稳态和动态流变学特性进行研究；通过影响因素试验，考察高温、低温、高湿和光照条件下B-MBG于0，5，10，15，20和30 d的pH值、黏度、含量和粒度变化。结果 初步稳定性试验显示B-MBG是澄清透明、质地均一的黄色半固体，具有明显的丁达尔效应，pH值为5.12±0.02，粒径为（14.95±0.04） nm，多分散指数为0.18±0.00，Zeta电位为（–28.6±0.66） mV，黏度为（3.44±0.09） Pa·s，包封率为（95.13±2.74）%，载药量为（0.47±0.01）%，未出现变色、沉淀及分层现象；流变学试验显示B-MBG呈现典型的假塑性流体特征，黏弹性模量不随时间变化而变化，弹性模量大于黏性模量，呈现凝胶态；影响因素试验表明30 d内高温、低温和高湿条件下其pH、药物含量和粒度无明显变化；光照对黏度无明显影响，但对pH、粒度和含量稳定性影响较大；20 d后高温和高湿对黏度具有显著影响。结论 流变学结果表明B-MBG的凝胶结构稳定，光照、高温、高湿对B-MBG的稳定性有一定影响，建议避光低温保存。

Abstract:

OBJECTIVE To study the stability and rheological characteristics of baicalin loaded in microemulsion-based gel(B-MBG). METHODS Preliminary stability test was used to study the appearance properties, micromorphology, pH, viscosity, content and particle size of B-MBG. The rheology test was utilized to study the steady-state and dynamic rheological properties of B-MBG. The influencing factor test was used to study the pH, viscosity, content and particle size changes of B-MBG on 0, 5, 10, 15, 20 and 30 d, in high temperature, low temperature, high humidity and light conditions. RESULTS Preliminary stability test showed that B-MBG was yellow, clear and transparent, with uniform texture and obvious Tyndall effect. The pH was 5.12±0.02, the mean particle size was (14.95±0.04)nm and polymer dispersity index was 0.18±0.00, Zeta potential was (-28.6±0.66)mV, viscosity was (3.44±0.09)Pa·s; the entrapment efficiency and drug loading were (95.13±2.74)% and (0.47±0.01)%. Rheological tests showed that B-MBG presented classic pseudoplastic fluid characteristics, the viscoelastic modulus would not change with time, the elastic modulus was greater than the viscous modulus, and B-MBG presented a gel state. Under the conditions of high temperature, low temperature and high humidity, the pH, drug content and particle size within 30 d had been proved by the influencing factors to be no significant different for B-MBG. Viscosity was not significantly affected by light, but pH, particle size and content stability were greatly affected by light. Under high temperature and high humidity conditions, the viscosity was proved to be a significant different after 20 d for B-MBG. CONCLUSION The structure is proved to be stable by rheological tests for B-MBG. The stability of B-MBG is affected by light, high temperature and high humidity. It is recommend that B-MBG should be stored at low temperature and protected from light.