Determination of the horny layer profile by tape stripping in combination with optical spectroscopy in the visible range as a prerequisite to quantify percutaneous absorption

A new method was developed to determine the horny layer profile of voluntee rs using tape stripping in combination with UV/visible spectroscopy. The op tical absorbance and the weight of corneocyte aggregates were compared as p arameters for the determination of the mass of the horny layer particles fi xed to the individual tapes. It was shown that the potential disturbances i nfluencing both parameters must be considered critically before calculating the correlation factor, found as R-mean(2) = 0.93 +/- 0.05. It was proven that the absorbance in the visible range is better suited than the weight t o quantify the amount of corneocyte aggregates removed by a single strip. T he new method allows an exact anatomical localization of the individual tap es and all data obtained within the depth profile of the stratum corneum. T his was exemplified by the determination of the penetration of chemical and physical UV filters into the horny layer.