Gupta S L, Higuchi W I, Ho N F
J Pharm Sci. 1985 Nov;74(11):1178-83. doi: 10.1002/jps.2600741109.
The dissolution rate of cholesterol monohydrate in various concentrations of sodium chenodeoxycholate (1) was significantly influenced by the addition of strong electrolytes. The mass transfer resistances decreased with increasing electrolyte concentrations and attained an asymptotic minimum value predicted and experimentally established for the convective/diffusion-controlled situation. Reduction of the interfacial barrier to dissolution was many times more sensitive to Mg2+ than to Na+ at equimolar concentrations. Cholesterol monohydrate solubilities increased nonlinearly with increasing 1 in 0.01 M phosphate buffer at pH 8.0 and was not influenced by the presence of strong electrolytes. Measured diffusion coefficients gave supporting evidence that the effective micellar size remained the same within the various experimental systems up to 116 mM chenodeoxycholate. The experimental findings indicated that the interfacial barrier is electrostatic in character. They are consistent with the phenomenon of diffusion of negatively charged micelles toward a negatively charged cholesterol monohydrate surface and the subsequent collision complex transfer of cholesterol molecules at the crystal surface. The results and mechanistic interpretations are also in accord with the previous model studies on cholesterol monohydrate dissolution in the presence of mixed micelles composed of nonionic and ionic surfactants.
一水合胆固醇在不同浓度鹅去氧胆酸钠（1）中的溶解速率受到强电解质添加的显著影响。传质阻力随着电解质浓度的增加而降低，并达到对流/扩散控制情况下预测和实验确定的渐近最小值。在等摩尔浓度下，界面溶解屏障对Mg2+的降低比对Na+敏感许多倍。在pH 8.0的0.01 M磷酸盐缓冲液中，一水合胆固醇的溶解度随着（1）浓度的增加而非线性增加，且不受强电解质存在的影响。测得的扩散系数提供了支持性证据，表明在高达116 mM鹅去氧胆酸钠的各种实验系统中，有效胶束大小保持不变。实验结果表明，界面屏障具有静电性质。它们与带负电荷的胶束向带负电荷的一水合胆固醇表面扩散以及随后胆固醇分子在晶体表面的碰撞复合物转移现象一致。这些结果和机理解释也与先前关于在由非离子和离子表面活性剂组成的混合胶束存在下，一水合胆固醇溶解的模型研究一致。
