LIGHT AND ELECTRON-MICROSCOPIC FINDINGS IN HUMAN EPIDERMIS RECONSTRUCTED IN-VITRO UPON TOPICAL APPLICATION OF LIPOSOMAL TRETINOIN

The topical application of tretinoin is a well-established approach to the treatment of acne vulgaris. However, induced inflammation, clinic ally addressed as a ''flare-up'', is a major drawback, Recently, clini cal and experimental investigations have hinted at a better tolerabili ty, with equal efficacy, if the active compound is liposomally encapsu lated, Using epidermis reconstructed in vitro, we compared the morphol ogical changes upon topical application of a liposomal form (0.05% and 0.025%) and conventional form (0.05%) light and electron microscopica lly, After 24 h several remarkable changes of the stratum corneum with all treatment modalities, representing inhibition of keratinisation w anted in acne vulgaris, were seen, When preparations of equal strength , i.e. 0.05%;, were compared, the changes representing toxic dermatiti s in the epidermis were more marked with the conventional form, Epider mis reconstructed in vitro treated with the Liposomal forms showed no significant differences due to either concentration, It is suggested t hat these changes correspond to the flare-up on clinical grounds, The in vitro findings further corroborate the hypothesis that Liposomal en capsulation can increase the benefit/risk ratio of an active compound applied to the skin.