In vitro safety assessment of papain on human skin: A qualitative Light and Transmission Electron Microscopy (TEM) study

papain is a thiol proteolytic enzyme widely used in dermatology that found applications in wound treatment. recently, papain was also used as absorption enhancer which can modify the peptide/protein material in the bilayer domain. we investigated papain safety using human skin that was exposed to papain in vitro at different times: 4, 24 and 48 hours. the samples were examined using light and transmission electron microscopy (tem) to study of the mechanisms involved in enhancer-skin interaction. after 24 hours, changes occurred in corneosomes. however, samples of 48 hours did not show major changes in agreement with the control. these findings indicated that papain could be used safely onto the skin.