JEADV Clinical Practice (Sep 2022)
Improvement of photoprotection with sunscreen formulas containing the cyclic merocyanine UVA1 absorber MCE: In vivo demonstration under simulated and real sun exposure conditions in three randomised controlled trials
Abstract
Abstract Background Chronic sun exposure induces skin damage leading to skin ageing and skin colour heterogeneity with hyperpigmented spots. In this process ultra violet A (UVA) rays highly contribute, especially long‐UVA (UVA1) supporting the need for an efficient photoprotection over the whole UV spectrum. A new UVA1 filter, methoxypropylamino cyclohexenylidene ethoxyethylcyanoacetate (MCE), with a pic of absorption at 385 nm, has been recently approved for use in sunscreen products. Objective Three randomised clinical studies were performed to evaluate the additional photoprotection afforded by a sunscreen formula containing MCE compared to state‐of‐the‐art sunscreen lacking absorption in the longest UVA1 wavelengths. Two studies were performed on European volunteers with UV‐controlled (UVA1, ultra violet B (UVB) + UVA) exposures and one on Indian volunteers under real sun exposures. Methods Three intraindividual trials (two randomised UV‐controlled and one real sun) were conducted on a total of 62 healthy subjects with Fitzpatrick III–IV and individual typology angle (ITA°) values between −18° and 35°. The MCE at 2% was formulated in a state‐of‐the‐art sun protection factor 30 sunscreen reference allowing to enlarge the absorption profile up to 400 nm. UV‐induced pigmentation was assessed by colorimetric measures and visual scoring at different time points after a single exposure to UVA1 (Study 1) or repeated exposures to daily UV radiation comprising both UVB and UVA (Study 2) or under real sun (Study 3). Results Whatever the study exposure condition (UVA1, UVB + UVA, real sun), the level of pigmentation was increased as attested by colorimetric parameters (decreased luminance L* and ITA° values) and visual scorings. In the three studies, the comparison showed higher prevention of hyperpigmentation with the sunscreen enlarged in the longest UVA1 wavelengths with MCE compared to the state‐of‐the‐art sunscreen. No side effects were reported. Conclusions MCE is a valuable UVA1 filter to improve photoprotection over the entire UV spectrum in state‐of‐the‐art sunscreens and limits the impact of UVA1 rays.
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