Phosphate film free of chromate, fluoride and nitrite on AZ31 magnesium alloy and its corrosion resistance

A phosphate solution free of chromate, fluoride and nitrite was prepared and an environment-friendly film was obtained on AZ31 magnesium alloy surface via the chemical deposition method. The morphology, composition, phase structure and its corrosion resistance were studied. The effects of film-forming temperature and free acid on corrosion resistance, microstructure and electrochemical behavior of the film were discussed. The results indicate that the corrosion resistance of AZ31 with the phosphate film was better than blank AZ31 substrate, which was most attributed to the great inhibitive action on the anodic dissolution and cathodic hydrogen evolution of the film.

苦豆碱阴道用温敏凝胶的流变学及释药行为研究

目的考察苦豆碱阴道用温敏原位凝胶的流变学性质,并预测其体内释放行为。方法采用冷溶法工艺,以泊洛沙姆407和泊洛沙姆188为材料制备温敏凝胶;倒置法检测苦豆碱温敏凝胶的胶凝温度和时间;流变仪测定流变学参数;采用无膜溶出模型评价体外释药性能;荧光成像法考察阴道局部滞留性。结果凝胶剂在室温下为淡黄色、均匀、透明的流体,黏度较低;在约33℃变为凝胶状假塑性流体,黏度上升;且经阴道模拟液稀释后,在37℃仍能形成凝胶。凝胶中苦豆碱的体外释放动力学行为符合Higuchi方程。通过成像与IR783荧光定量分析可知:苦豆碱温敏凝胶在小鼠阴道内至少可停留48 h,但其溶液剂在24 h时几乎观察不到荧光信号。结论苦豆碱温敏凝胶具适宜的胶凝温度和良好的流变学性质,可延长药物在阴道内的滞留时间,延缓药物的释放,能满足阴道局部用药的要求。

秦皮温敏眼用即型凝胶的制备与体内外研究

目的研究秦皮温敏眼用即型凝胶的体外性质,刺激性,药物释放机制及眼部消除动力学。方法采用无膜溶蚀模型研究药物的释放机制。以凝胶外观、pH值、胶凝温度、含量等变化为指标考察强光照射、冷冻及加速实验条件下凝胶的稳定性。采用Draize眼部刺激性试验评价单次和多次给药后凝胶对兔眼的刺激性。使用统计矩法评价了药物在家兔眼部的消除动力学特征。结果该制剂稳定性好,无刺激,药物释放主要受胶凝溶蚀控制,符合零级动力学过程。药动学结果显示,凝胶组AUC和MRT明显高于滴眼液组(P<0.05)。结论秦皮温敏眼用即型凝胶可明显延长药物在眼部的滞留时间,提高药物的生物利用度,展现出良好的眼部应用前景。