RECONSTRUCTED EPIDERMIS AND FULL-THICKNESS SKIN FOR ABSORPTION TESTING: INFLUENCE OF THE VEHICLES USED ON STEROID PERMEATION.

This study by researchers at the Free University of Berlin demonstrated that MatTek’s EpiDerm in vitro human skin tissue equivalent and EpiDermFT full-thickness in vitro human skin tissue equivalent can be used in the development of topical dermatics and for hazard analysis of toxic compounds and their formulations. A protocol for percutaneous absorption studies has been validated, based on the use of reconstructed human epidermis (RhE) and aqueous solutions of test substances. However, it is often the case that it is more-complex formulations of drugs or chemicals which will make contact with the skin surface. To investigate whether reconstructed human epidermis (EpiDerm) and the reconstructed full-thickness skin model (EpiDerm-FT) can be used to predict uptake from formulations, we compared the permeation of hydrocortisone and testosterone when applied in emulsion form and as a solution containing the penetration enhancer ethanol. Human and pig skin and a non-cornified alveolar model served as references. The results were compared with steroid release from the formulations. The permeation rates of the steroids were ranked as: alveolar model >> RhE > FT-model, pig skin > human skin. In accordance with the rapid hydrocortisone release from the formulations, the permeation rates of this steroid exceeded those of testosterone. Only minor differences were observed when comparing the testosterone formulations, in terms of release and permeation. However, the ranking of the permeation of the hydrocortisone formulations was: solution > w/o emulsion > o/w emulsion, which permitted the elucidation of penetration enhancing effects, which is not possible with drug release studies. Differences in penetration were most obvious with native skin and reconstructed tissues which exhibited a well-developed penetration barrier. In conclusion, reconstructed human epidermis (RhE) and skin preparations may be useful in the development of topical dermatics, and in the framework of hazard analysis of toxic compounds and their various formulations.

AIR-606, EFT-306, EpiAirway, EpiDerm-FT, EpiDermFT, Ethanol, Human skin, Hydrocortisone, OECD TG 28, Oil-in-water emulstion, Penetration enhancer, Percutaneous absorption, Permeability coefficient Papp, Pig skin, SkinEthic®, Steroid permeation, Testosterone, Water-in-oil emulsion