Barry B W, El Eini D I
J Pharm Pharmacol. 1976 Mar;28(3):219-27. doi: 10.1111/j.2042-7158.1976.tb04134.x.
The lag-time method of diffusion has been used to investigate permeation of hydrocortisone, dexamethasone, testosterone and progesterone across cellulose acetate membranes between 10 degrees and 40 degrees. The process depended mainly on membrane-water partition coefficients of the steroids so that the least polar compound permeated the fastest. Permeation generally increased with increasing temperature and from the temperature dependance of the diffusion coefficient, energies of activation were derived. The varied from 2.4 kcal mol(-1) for the least polar steroid, progesterone, to 7.4 kcal mol(-1) for the most polar, hydrocortisone. n-C16 Polyoxyethylene surfactants when present below and above the cmc increased the steroids permeation rates. Varying the polyoxyethylene chain length (OE equals 17-63) did not significantly affect permeation rates, suggesting that the enhancing effect of surfactants arises from their hydrophobic group.
扩散的滞后时间法已被用于研究氢化可的松、地塞米松、睾酮和孕酮在10℃至40℃之间透过醋酸纤维素膜的渗透情况。该过程主要取决于甾体激素的膜 - 水分配系数，因此极性最小的化合物渗透最快。渗透通常随温度升高而增加，并且根据扩散系数的温度依赖性得出了活化能。其范围从极性最小的甾体激素孕酮的2.4千卡·摩尔⁻¹到极性最大的氢化可的松的7.4千卡·摩尔⁻¹。当n - C16聚氧乙烯表面活性剂低于和高于临界胶束浓度（cmc）时，会增加甾体激素的渗透速率。改变聚氧乙烯链长度（OE等于17 - 63）对渗透速率没有显著影响，这表明表面活性剂的增强作用源于其疏水基团。
