Khalil S A, Iwuagwu M
J Pharm Sci. 1978 Feb;67(2):287-9. doi: 10.1002/jps.2600670250.
Some steroids used in oral contraceptives were adsorbed significantly by magnesium trisilicate. The adsorption affinity followed the sequence: ethindrone greater than mestranol greater than norethindrone greater than ethinyl estradiol. Adsorption data obtained at relatively low initial concentrations fitted a Langmuir plot; the values for monolayer adsorption ranged between 0.24 and 0.32 mg/g. At higher concentrations of the steroids, multilayer adsorption occurred. The results of desorption experiments made at 37 degrees in water and 0.05 N HCl suggested that desorption was incomplete and depended on the amount of steroid adsorbed. During the dissolution testing of a brand of contraceptive tablets containing norethindrone acetate, the presence of 0.5% (w/v) magnesium trisilicate in the medium resulted in almost complete reduction in the amount of the steroid remaining in solution after 1 hr.
一些口服避孕药中使用的类固醇被三硅酸镁显著吸附。吸附亲和力顺序为：炔诺酮大于炔雌醇甲醚大于炔诺孕酮大于炔雌醇。在相对较低的初始浓度下获得的吸附数据符合朗缪尔曲线；单层吸附值在0.24至0.32毫克/克之间。在较高的类固醇浓度下，会发生多层吸附。在37摄氏度的水和0.05N盐酸中进行的解吸实验结果表明，解吸不完全，且取决于吸附的类固醇量。在对一种含醋酸炔诺孕酮的避孕片剂进行溶出度测试时，介质中存在0.5%（w/v）的三硅酸镁导致1小时后溶液中剩余的类固醇量几乎完全减少。
