Preclinical and clinical studies to evaluate cutaneous biodistribution, safety and efficacy of UV filters encapsulated in mesoporous silica SBA-15

Innovative technologies have been designed to improve efficacy and safety of chemical UV filters. Encapsulation can enhance efficacy and reduce transdermal permeation and systemic exposure. The aims of this work were (i) to determine the cutaneous biodistribution of avobenzone (AVO), oxybenzone (OXY), and octyl methoxycinnamate (OMC) incorporated in mesoporous silica SBA-15 and (ii) to perform preclinical (in vitro) and (iii) clinical safety studies to demonstrate their innocuity and to evaluate sun protection factor (SPF) in humans. Skin penetration studies showed that deposition of OXY and AVO in porcine and human skin after application of stick formulation with incorporated filters (stick incorporated filters) was significantly lower than from a marketed (non-encapsulated) stick. Cutaneous deposition and transdermal permeation of OXY in and across human skin were 3.8-and 13.4- fold lower, respectively, after application of stick entrapped filters. Biodistribution results showed that encapsulation in SBA-15 decreased AVO and OXY penetration reaching porcine and human dermis. Greater deposition (and permeation) of OXY in porcine skin than in human skin, pointed to the role of follicular transport. Stick incorporated filters had good biocompatibility in vivo and safety profiles, even under sun-exposed conditions. Entrapment of UV filters improved the SPF by 26% and produced the same SPF profile as a marketed stick. Overall, the results showed that SBA-15 enabled safety and efficacy of UV filters to be increased.