RESUMEN
BACKGROUND: There is a serious concern about the topical and systemic absorption of organic ultraviolet filters in sunscreen formulations and subsequent phototoxic and photo allergic reactions. Ideally, a sunscreen should localize in the surface of stratum corneum and create a barrier against UV radiation, but not penetrate into the underlying viable tissues and systemic circulation. PURPOSE: The objective of the present study was to determine the effects of ß-cyclodextrin (ß-CDX) complexation on the transdermal penetration of 3 commonly used sun blocking agents, Eusolex ® 4360 (avobenzone), Eusolex ® 9020 (Oxybenzone) and Eusolex ® 232 (Ensulizole). METHODS: The complexation of the sunscreen agents with ß-CDX was performed by 3 methods and confirmed by differential scanning calorimetry (DSC). Sunscreens, and their physical mixtures and complexes with ß-CDX were introduced into a model cream base (o/w emulsion). To find out the influence of ß-CDX, sunscreen creams were applied to the rat skin in vitro in standard Franz diffusion cells and the amount of sunscreen permeated after 6 h was assessed by HPLC. RESULTS: The skin penetration flux of the UV filters was significantly reduced (415 fold) by complexation with ß-CDX. Complexation also could prolong absorption lag time of sun blocking agents to more than 150 min. CONCLUSION: Considering the ability of ß-CDX complexation in the reduction of flux and enhancement ratio as well as prolongation of absorption lag time, this technique could be very helpful for reducing systemic absorption of the UV filters and subsequent toxicity and allergic reaction.