Analysis of the penetration process of drugs and cosmetic products into the skin by tape stripping in combination with spectroscopic measurements

A new method is described for analyzing the penetration of drugs and cosmetic products into the skin. This method combines the tape stripping procedure with UV/VIS spectroscopic measurements to determine the amount of corneocytes on the tapes removed by their scattering properties. The UV/VIS spectroscopic measurements were made using a Perkin Elmer Lambda 20 double beam spectrophotometer, which had been modified to obtain a rectangular beam diameter of 10 times 10 mm 2 . The absorbance measured at 430 nm was taken as measure for the mass of the corneocyte aggregates placed on the individual tapes. It was proven by weighing, laser scanning microscopy and spatial-spectral density analysis, that the absorbance in the visible range is better suited than the weight to quantify the amount of corneocyte aggregates removed by a single strip. This novel combination method permits to determine the actual position of sunscreen components in the stratum corneum.