Substantivity of sunscreens —in vitro evaluation of the transdermal permeation characteristics of some benzophenone derivatives

Publisher Website
Google Scholar
Abstract
Synopsis: The in vitro permeation through excised hairless mouse skin of a series of 4‐O‐(N, N‐dimethylaminoalkyl)‐benzophenones, non‐quaternarized and quaternarized, and of two commercial benzophenone sunscreens, taken as reference compounds, was investigated. The aim of the study was to verify the skin penetration of the highly skin‐substantive quaternary ammonium derivatives, in comparison with their parent, non‐quaternarized compounds. While the quaternary derivatives proved unable to permeate the skin during the period of observation (45 h), their parent amine hydrochlorides and the reference sunscreens (2‐hydroxy‐4‐methoxy‐benzophenone‐5‐sulphonic acid and 2,2′‐dihydroxy‐4,4′‐dimethoxy‐benzophenone 5,5′‐sodium disulphonate), showed appreciable transdermal fluxes.These data indicate that the presence of a quaternary ammonium group in a molecule, besides inducing a high affinity for cutaneous keratin, may result in hindered or reduced transdermal (and possibly systemic) absorption. Both features may contribute in improving the safety of a cosmetic sunscreen.