The aim of this study was to develop an ex vivo method that allows to quantify the transfollicular penetration of topically applied substances by combining microdialysis and selective follicular closure with varnish. An experimental setup with three skin areas on ex vivo intact porcine ear skin was designed (varnish on hair follicle, varnish next to hair follicle, no varnish). On each area, 10 µl/cm² caffeine-hydroxyethyl-cellulose-gel was applied. Samples were collected for 22 h by microdialysis. After sampling, the skin layers were separated, homogenized and caffeine was quantified by high pressure liquid chromatography (HPLC) in all samples. Potential impact of the varnish placed next to the follicle by tension on the follicle during the drying process was monitored by a microscopic setup and could be excluded. The microdialysis and homogenization study showed a significantly reduced penetration of caffeine when the hair follicles were closed. In areas with open hair follicles caffeine was detected already in the first ten minutes after application. The reported novel combination of two methods is suitable to investigate ex vivo transfollicular penetration. Possible impact of the closure material in the control area can be ruled out by adjusting the design of the control area in future studies.

本研究的目的是开发一种体外方法，通过将微透析和选择性毛囊闭合与清漆相结合，可以量化局部应用物质的跨毛囊渗透。设计了在离体完整猪耳朵皮肤上具有三个皮肤区域的实验装置（毛囊上的清漆、毛囊旁边的清漆、无清漆）。在每个区域，10 µl/cm ²应用了咖啡因-羟乙基-纤维素-凝胶。通过微透析收集样品 22 小时。取样后，将皮肤层分离、均质化，并通过高压液相色谱 (HPLC) 对所有样品中的咖啡因进行定量。在干燥过程中通过对毛囊的张力放置在毛囊旁边的清漆的潜在影响通过显微装置监测并且可以被排除。微透析和均质化研究表明，当毛囊闭合时，咖啡因的渗透显着降低。在毛囊开放的区域，在使用后的前十分钟内已经检测到咖啡因。报道的两种方法的新组合适用于离体研究经滤泡渗透。通过在未来的研究中调整控制区域的设计，可以排除封闭材料对控制区域的可能影响。