EVALUATION OF BARRIER CREAMS - AN IN-VITRO TECHNIQUE ON HUMAN SKIN

A method was developed to measure in vitro on human skin the effective ness of barrier creams against three dyes (eosin, methyl-violet and oi l red O) with different n-octanol/water partition coefficients (0.19, 29.8 and 165, respectively). Some galenic properties (water washabilit y, water content and viscosity) of the products were also evaluated to try to understand the mechanisms of such a protection. The barrier cr eams were assayed by measurements of the dyes in the epidermis of prot ected skin samples after an application time of 30 min. Whereas some p roducts showed some degree of protection, as claimed on the packaging, we demonstrated in several cases disagreement with the manufacturer's information. Surprisingly, petrolatum was found to provide the best p rotection of all tested products in our in vitro model. There was no c orrelation between the galenic parameters of the assayed products and the level of protections, indicating that neither the water content no r the consistence of the formulations influenced the protection effect iveness. In conclusion, regarding the possible skin effects of some ir ritants, our results stress that barrier creams should be used with ca ution, knowing the protection limits of some of the formulations marke ted.