Engineering Research Center of Modern Chinese Medicine Discovery and Preparation Technique, Ministry of Education, 88 Yuquan Road, Tianjin 300193, PR China.
Int J Pharm. 2011 May 30;410(1-2):31-40. doi: 10.1016/j.ijpharm.2011.03.007. Epub 2011 Mar 22.
Baicalin has been reported to have anti-inflammatory and anti-cataract effects on eye tissues, but it has a low bioavailability partly due to its poor stability of baicalin, the special anatomic structure and efficient protective mechanism of eyes. The aim of this study was to investigate the correlation between the stability of baicalin and in situ pH-triggered gelling system. Carbopol(®) 974P (0.3%, w/v) was used as the gelling agent combined with hydroxypropylmethylcellulose E4M (0.6%, w/v) which acted as a viscosity enhancing agent. In vitro and in vivo evaluations were performed using several techniques, namely confocal scanning light microscopy analysis, rheometry, Gamma scintigraphic technique and microdialysis method. The rheological behavior showed a significant enhancement in gel strength under physiological conditions, and the formulation provided sustained release of the drug over an 8-h period. In elimination studies, the radioactivity of formulation was always higher than that of the control solution. Additionally, the AUC and C(max) values were 6.1-fold and 3.6-fold higher than those of the control solution, respectively. The results demonstrated that an in situ pH-triggered gelling system have better ability to keep baicalin stable and retain drug release than marketed baicalin eye drops to enhance the ocular bioavailability.
黄芩苷具有抗炎和抗白内障作用，对眼组织有影响，但由于其黄芩苷稳定性差，眼睛具有特殊的解剖结构和有效的保护机制，生物利用度较低。本研究旨在探讨黄芩苷的稳定性与原位 pH 触发凝胶系统之间的相关性。卡波姆（®）974P（0.3%，w/v）用作凝胶剂，与羟丙基甲基纤维素 E4M（0.6%，w/v）结合使用，羟丙基甲基纤维素 E4M 用作增粘剂。使用几种技术（共聚焦扫描光显微镜分析、流变学、γ闪烁技术和微透析法）进行了体外和体内评价。流变行为表明，在生理条件下凝胶强度显著增强，该制剂在 8 小时内提供了药物的持续释放。在消除研究中，制剂的放射性始终高于对照溶液。此外，AUC 和 C（max）值分别比对照溶液高 6.1 倍和 3.6 倍。结果表明，原位 pH 触发凝胶系统比市售黄芩苷滴眼液具有更好的保持黄芩苷稳定和保持药物释放的能力，从而提高眼部生物利用度。
