蝙蝠葛碱缓释片溶解度和解离常数测定

目的：测定蝙蝠葛酚性碱缓释片的溶解度与解离常数，以指导缓释片的处方设计。方法：采用紫外分光光度法测定溶解度和解离常数。结果：蝙蝠葛酚性碱在水中的溶解度为5．28mg／ml，用柠檬酸增溶后的溶解度为71．12mg／ml，在不同pH值缓冲液中溶解度随着pH值的升高呈现先减少后增大的趋势；蝙蝠葛酚性碱的酸性解离常数pKa=8．20±0．03，碱性解离常数PKb=10．59±0．06。结论：蝙蝠葛酚性碱的水溶性较差，柠檬酸对它具有较好的增溶效果，可通过控制环境的PH值来控制其吸收速率。

Determination of Solubility and Dissociation Constant of Sustained Release Tablet of Phenolic Alkaloids of Menispermum Dauricum

Objective. To determine the solubility and dissociation constant of sustained release tablet of phenolic alkaloids of Menispermum Dauricum （PAMD） for preformutation of the sustained release tablets. Methods： The solubility and dissociation constant were determined using ultraviolet spectrophotometry. Results： The solubility of PAMD was 5.28 mg/ml in water, and it was 71. 12 mg/ml after being solubilized by citric acid. Its solubility was found to decrease firstly and increase afterwards with the increase of pH value in various phosphate buffer solutions （PBS）. The pKa （negative logarithm of acidic dissociation constant） of PAMI）was 8.20±0.03 and the pKb（negative logarithm of basic dissociation constant） was 10.59±0.06. Conclusion： PAMD is a slightly water-soluble drug; citric acid is an ideal solubilizer; and the drug absorption rate can be controlled by regulating the pH value of environment.