摘要：To study the effect of hydration on skin absorption, we investigated penetration across human skin of twelve model chemicals having steroidal structure but different molecular weight and compared the steady-state penetration rate ( J ) and lag-time ( t ) across hydration intact skin ( J h and t h) with that across dehydrated intact skin ( J d and t d). Stratum corneum (SC) thickness of hydrated (52 μm) is 3.3 times that of dehydrated skin (16 μm). Transepidermal water loss (TEWL) of hydrated (7.6±2.1 g/m2/h) is twice that of dehydrated skin (3.4±1.6 g/m2/h, p <0.05) which are similar to in vivo values, suggesting the SC barrier function was recovered. The ratio of J h/ J d ranged between 0.7 and 3.6 (average of 1.9). On the other hand, the ratio of t h/ t d was almost constant (average of 0.8). Ratios of J h/ J d and t h/ t d were independent of MW and K o/w. In percutaneous absorption experiments in vitro , skin was preserved in culture medium until use and SC might swell during that time. Therefore, we consider the possibility that J and t varied between hydrated and dehydrated skin. We confirmed the difference of J and t between hydrated and dehydrated skin in vitro and now need to define these results under in vivo condition.
关键词：hydrated skin;dehydrated skin;penetration flux;lag-time;in vitro experiment;transepidermal water loss (TEWL)
