Study of the influence of alcohol on the photostability of four UV filters.

ABSTRACT

OBJECTIVE: Spray formulations are currently under development in the field of topical photoprotection. Such forms are characterized by their high fluidity, a property that is obtained by the presence of alcohol in the formula. The purpose of this work was to study the influence of ethanol in sunscreens on the photoprotective efficacy as well as the photostability of UV filters. MATERIALS AND METHODS: The filters tested were octyl methoxycinnamate (OMC), PEG-25 PABA, octyl salicylate and butyl methoxydibenzoylmethane (BMDBM) at their maximum concentration authorized by European regulations and in the presence of increasing amounts of alcohol, up to 15% (w/w). RESULTS: The effect of the presence of alcohol on the efficacy of the filters and their photostability varies depending on the molecule considered. Alcohol has no effect on octyl salicylate, either on its efficacy or its photostability. However, filter stabilization is seen for BMDBM and PEG-25 PABA. CONCLUSIONS: Although these differences are significant, they are not great enough to justify large-scale use of ethanol in sunscreen products due to some of its properties, such as flammability.