Li S K, Ghanem A H, Peck K D, Higuchi W I
Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City 84112, USA.
J Pharm Sci. 1997 Jun;86(6):680-9. doi: 10.1021/js960479m.
The effects of permeant charge (z) on iontophoretic-enhanced transport were investigated with synthetic Nucleopore membranes and with human epidermal membranes using a four-electrode potentiostat with side-by-side diffusion cells. The modified Nernst-Planck model (Nernst-Planck theory with an additional transport term to correct for the effect of the convective solvent flow due to electroosmosis) was first examined in a Nuclepore membrane system with model permeants calcein (z = -4), salicylate (z = -1), and a series of polystyrene sulfonates (from monomer to molecular weight of approximately 8000 with a z range of -1 to approximately -40). The flux enhancement (E) for each permeant was determined at 470 mV. Mannitol (a neutral molecule) was used as a probe to determine a correction for convective solvent flow under the same applied voltage conditions. Good agreement between the experimental results and the predictions from the modified Nernst-Planck model was found for calcein, salicylate, and polystyrene sulfonates up to molecular weight of approximately 1800 (z approximately -8). The flux enhancements for the higher molecular weight polystyrene sulfonates with greater z values were more than a factor of three lower than theoretical predictions; the electrophoretic effect and counterion binding to the permeants are proposed as possible explanations for these discrepancies between experiment and the modified Nernst-Planck theory. In the studies with human epidermal membranes, iontophoretic flux enhancements for calcein, salicylate, and taurocholate were determined at 250 and/or 470 mV. The flux enhancements were generally consistent with the results calculated from the modified Nernst-Planck model.
使用带有并排扩散池的四电极恒电位仪，通过合成的核孔膜和人表皮膜研究了渗透电荷（z）对离子电渗增强转运的影响。首先在核孔膜系统中，使用模型渗透剂钙黄绿素（z = -4）、水杨酸盐（z = -1）以及一系列聚苯乙烯磺酸盐（从单体到分子量约为8000，z范围为-1至约-40）检验了修正的能斯特-普朗克模型（在能斯特-普朗克理论基础上增加一个传输项以校正电渗引起的对流溶剂流的影响）。在470 mV下测定了每种渗透剂的通量增强（E）。甘露醇（一种中性分子）用作探针，以确定在相同施加电压条件下对流溶剂流的校正值。对于钙黄绿素、水杨酸盐和分子量高达约1800（z约为-8）的聚苯乙烯磺酸盐，实验结果与修正的能斯特-普朗克模型的预测结果吻合良好。对于z值更大的高分子量聚苯乙烯磺酸盐，其通量增强比理论预测低三倍以上；电泳效应和抗衡离子与渗透剂的结合被认为是实验与修正的能斯特-普朗克理论之间这些差异的可能解释。在用人表皮膜进行的研究中，在250和/或470 mV下测定了钙黄绿素、水杨酸盐和牛磺胆酸盐的离子电渗通量增强。通量增强通常与根据修正的能斯特-普朗克模型计算的结果一致。
