Bioadhesive liquid crystal systems for octyl methoxycinnamate skin delivery

Excessive exposure to ultraviolet radiation stemmed from sunlight can cause harm to human skin. An alternative to avoid and reduce the effects of ultraviolet radiation is the use of sunscreens. The sunscreen octyl methoxycinnamate (OMC) is one of the most used filters globally. Still, studies have indicated systemic absorption of this product and subsequent amendment and impaired functioning of the endocrine system. Surfactant systems as liquid crystals systems are used to improve the delivery and efficacy of active ingredients. The OMC incorporated into liquid crystals can have greater retention in the skin's outer layers and lower percutaneous absorption, avoiding their harmful systemic effects. This work aimed to develop and characterize surfactant-based systems for OMC skin delivery and evaluate the in vitro skin permeation and retention properties. Polarized light microscopy and SAXS showed that the selected formulations presented cubic mesophases. The formulations presented pseudoplastic behaviour and the F1 and F1F formulations presented the highest viscosity of all formulations. The three formulations presented controlled release over time, being the F2F and F3F presenting high release rates when compared to F1F. The formulation F3F presented the higher stratum corneum retention and lower epidermis and dermis retention when compared to F1F and F2F. The formultions manteined the sun protecting factor of OMC, being similar to the finds in the literature for this sunscreen. Thus, the bioadhesive LCS developed in this work have great potential for OMC delivery to the skin.