Drug permeation through human skin: I. Effect of storage conditions of skin.

The purpose of this study was to establish conditions for the preparation and storage of excised human skin such that it most closely retained the permeation characteristics seen with skin samples studied immediately after having been removed from cadavers. Using skin taken from the inner thighs of cadavers within 48 hr post mortem, we have compared drug permeation through samples that were used immediately following removal with samples that had been stored in either the frozen or dried state. With the chromone acid under investigation, it was found that samples of stratum corneum attached to the underlying epidermis used without prior storage consistently showed less permeation than samples taken from the same individual that had been frozen at -17 degrees C upon removal and then thawed before permeation studies were started. However, drug permeation through samples of stratum corneum plus epidermis that had been allowed to dry under controlled humidity conditions at room temperature were found to be similar to those obtained with fresh skin. These results indicate that dried skin, when appropriately rehydrated before use, exhibits rates of drug permeation similar to those found with fresh skin. With the chromone acids under investigation, the use of frozen samples of excised skin should be avoided since the extent of permeation exceeds that obtained with fresh skin samples.