The impact of methoxypropylamino cyclohexenylidene ethoxyethylcyanoacetate (MCE) UVA1 filter on pigmentary and ageing signs: An outdoor prospective 8-week randomized, intra-individual comparative study in two populations of different genetic background

Background: Of all ultraviolet (UV) radiations reaching the earth, UVA1 rays have a higher potential of penetrating and producing clinically harmful consequences. While UV radiations up to 370 nm are well-blocked by current sunscreens, a photoprotection gap remains for the UVA1 wavelengths between 370 and 400 nm.

Objective: This study was to assess under outdoor summer conditions the impact on pigmentation and skin ageing signs of a protection against UVA1 using methoxypropylamino cyclohexenylidene ethoxyethylcyanoacetate (MCE) filter added to a reference SPF50 sunscreen, in comparison with the same sunscreen without the MCE filter.

Materials and methods: This prospective randomized comparative intra-individual study was conducted in 113 women in Brazil and China. Subjects had their face and two forearms exposed twice-daily to a 1-h outdoor sunlight exposure over 8 weeks. Before exposure, the SPF50 sunscreen containing 3% MCE was applied on one half-face and one forearm and the same reference product without MCE on the other half-face and forearm. Primary study endpoint was skin colour changes (chromametry). Other endpoints included expert panel grading of pigmentation and facial skin ageing, and naïve panel assessment of facial skin radiance and homogeneity.

Results: After 8 weeks, the skin was darker on both forearms but the increase in sun-induced pigmentation was smaller with the SPF50/MCE sunscreen. Expert panel evaluations showed no change in severity scores for pigmentation and a decreased severity scores for facial skin ageing in areas protected with the SPF50/MCE product: severity scores in areas protected with the SPF50 alone were either increased (pigmentation) or unchanged (skin ageing). Naïve panel evaluations of skin radiance and homogeneity showed statistically significant superiority of the SPF50/MCE product.

Conclusion: Overall, this study demonstrates that a protection with the SPF50/MCE sunscreen significantly reduces pigmentation and ageing signs compared to the same SPF50 sunscreen.