In vitro retinoic acid release and skin permeation from different liposome formulations

The effect of including charged phospholipids (both negative and positive) and/or cholesterol in liposomal formulations on retinoic acid (RA) in vitro release and permeation through human stratum corneum and epidermis was studied. No significant difference in RA release was observed comparing the different liposomal formulations tested. On the contrary, positively charged liposomes provided significantly higher RA skin permeation compared to negatively charged vesicles which, in turn, showed RA permeation through the skin similar to that obtained from neutral liposomes. Furthermore, the inclusion of cholesterol in charged liposomes did not significantly affect RA skin permeation.