Stripping method to quantify absorption of two sunscreens in human.

With the aim to know the remanence of two sunscreens, PEG-25 PABA and benzophenone, two cases have been considered: the application of aqueous solution of two filters studied for the application of oil-in-water (O/W) emulsions containing the same two filters on the skin of 21 voluntary women. In order to determine the quantity of filter remaining in the stratum corneum after times of application, which vary from 1 to 7 h, a series of six strippings have been carried out. The sunscreen agents were assessed by HPLC. With this study, it has been possible to emphasize the best remanence of benzophenone 4. Moreover, the incorporation of photo-protective agents in a O/W emulsion promotes their penetration, and this is particularly due to benzophenone 4.