In order to enhance the optical clearing effect of topically applied optical clearing agents (OCAs), we evaluated the effect of propylene glycol (PG) as a chemical penetration enhancer (PE) on optical clearing of skin in vitro by observation and measurement of optical-transmittance and diffuse-reflectance spectra. Three OCAs, i.e., glycerol, D-sorbitol and PEG400, and two other penetration enhancers, Azone and Thiazone, were used in this study. The results indicated that the decrease of reduced scattering coefficient caused by OCA/PG was larger than that by pure OCA, and the change by OCA/water was the least after the same treatment time. There were significant differences for the reduced scattering coefficient at 630 nm after 120 min application of agents between OCA and OCA/PG. The efficacy of optical clearing caused by OCA/PG depended on the OCA itself. When PEG400 was mixed with three different PEs, we found the optical clearing were different. The penetration enhancing ability of PG was much better compared to Azone, and suboptimal to Thiazone. Also, this study provides evidence for the use of PG as a PE in order to improve skin optical clearing.

为探讨在体皮肤实验中最为简便有效的给药方式, 将化学渗透促进剂噻酮与聚乙二醇400（PEG400）的混合溶液直接作用于去除部分角质和含角质的在体大鼠皮肤, 利用CCD拍照进行直观观察, 并通过反射光谱的变化来反映皮肤光透明效果, 同时与单纯PEG400作用进行了对比。结果表明：混合溶液可以使去除部分角质皮肤在15 min内反射光谱明显下降, 并产生显著的光透明效果, 30 min后皮肤更加透明; 而单纯PEG400以及未去除角质层的完整皮肤均无光透明效果。因此, 结合物理方法去除部分角质层、并添加促渗剂噻酮, 能以非侵入方式, 快速、有效提高PEG400对在体皮肤的光透明效果。