Craane-van Hinsberg W H, Verhoef J C, Bax L J, Junginger H E, Boddé H E
Leiden/Amsterdam Center for Drug Research, Division of Pharmaceutical Technology, Leiden University, The Netherlands.
Pharm Res. 1995 Oct;12(10):1506-12. doi: 10.1023/a:1016243706415.
Iontophoresis in vitro was performed in a transport cell (0.79 cm2 area available for percutaneous transport) by 8-hours application of a pulsed constant current of 100 Hz, 50% duty cycle and 0.26 mA.cm-2 current density delivered by a pair of Ag/AgCl electrodes, of which the anode was facing the anatomical surface of the skin samples.
The initial resistances of human stratum corneum and shed snake skin samples were of the same order of magnitude (20-24 k omega.cm2) and both skin species showed a comparable resistance-decrease profile during 8-hours iontophoresis, indicating that the resistances were mainly determined by the stratum corneum and not greatly influenced by the appendageal structures. The initial resistances of the skin samples pretreated with dodecyl-azone were less than 50% of the values of untreated samples. Because dodecylazone is known to perturb the ordering of the intercellular lipids, the effect of azone on the resistance confirms that the resistance mainly resides within the intercellular lipids of the stratum corneum. No correlation was found between the iontophoretic DGAVP-flux and the conductance of human skin. For shed snake skin, however, a good correlation was found, indicating that the iontophoretic permeability of human skin in vitro for a peptide such as DGAVP is, unlike shed snake skin, not related to its overall permeability to ions. While the initial resistances of both human and snake skin were in the same order of magnitude and showed the same declining profile during iontophoresis, the steady state iontophoretic DGAVP flux across human stratum corneum was approximately 140 times larger than through shed snake skin. These findings suggest that small ions follow pathways common to both skin types, presumably the intercellular route, while the peptide on the other hand is transported differently: across snake skin presumably along intercellular pathways only, but across human stratum corneum along additional pathways (most likely of appendageal origin) as well. This interpretation is supported by the observations made of the effects of dodecyl-azone on DGAVP-iontophoresis. Pretreatment with dodecyl-azone did not significantly change steady state fluxes and lag times of DGAVP-iontophoresis across human stratum corneum, but resulted in a significant 3-fold lag time decrease and a 3-fold flux increase of DGAVP-iontophoresis across snake skin.
The results of these in vitro studies emphasize the importance of the appendageal pathway for iontophoretic peptide transport across human stratum corneum.
在一个传输池中进行体外离子导入实验（有0.79 cm²的面积可用于经皮转运），通过一对Ag/AgCl电极施加频率为100 Hz、占空比为50%、电流密度为0.26 mA·cm⁻²的脉冲恒流8小时，其中阳极朝向皮肤样本的解剖表面。
人角质层和蜕蛇皮样本的初始电阻处于同一数量级（20 - 24 kΩ·cm²），并且在8小时的离子导入过程中，两种皮肤类型都呈现出类似的电阻下降曲线，这表明电阻主要由角质层决定，而受附属器结构的影响不大。用十二烷基氮酮预处理的皮肤样本的初始电阻小于未处理样本值的50%。由于已知十二烷基氮酮会扰乱细胞间脂质的排列，氮酮对电阻的影响证实了电阻主要存在于角质层的细胞间脂质中。在人皮肤的离子导入DGAVP通量和电导率之间未发现相关性。然而，对于蜕蛇皮，发现了良好的相关性，这表明人皮肤体外对诸如DGAVP这样的肽的离子导入通透性与蜕蛇皮不同，与人皮肤对离子的整体通透性无关。虽然人和蛇皮的初始电阻处于同一数量级，并且在离子导入过程中呈现相同的下降曲线，但经人角质层的稳态离子导入DGAVP通量大约比经蜕蛇皮的大140倍。这些发现表明，小离子遵循两种皮肤类型共有的途径，大概是细胞间途径，而另一方面，肽的转运方式不同：经蛇皮大概仅沿细胞间途径，而经人角质层还沿其他途径（很可能起源于附属器）。十二烷基氮酮对DGAVP离子导入的影响的观察结果支持了这一解释。用十二烷基氮酮预处理并未显著改变经人角质层的DGAVP离子导入的稳态通量和滞后时间，但导致经蛇皮的DGAVP离子导入的滞后时间显著减少3倍，通量增加3倍。
这些体外研究结果强调了附属器途径在经皮离子导入肽通过人角质层转运中的重要性。
