New Combination of Ultraviolet Absorbers in an Oily Emollient Increases Sunscreen Efficacy and Photostability

Abstract

IntroductionIt is now recognized that to adequately protect skin from sun damage, sunscreens require a photostable combination of ultraviolet (UV) filters with a suitable level of UVA protection. The total amount of UV filters should be as low as possible to avoid adverse skin reactions, potential environmental impact, and to ensure acceptable texture for better application and usage.MethodsA synergistic combination of UV filters was selected to obtain a high sun protection factor (SPF) and UVA protection factor (UVA-PF). An oily vehicle was then added to the formula to improve the solubility and the photostability of the lipophilic UV filters.ResultsThe combination of filters, i.e., terephthalylidene dicamphor sulfonic acid (TDSA), bis-ethylhexyloxyphenol methoxyphenyl triazin (BEMT), and butyl methoxy dibenzoyl methane (BMDM), obtained an elevated SPF as well as a high UVA-PF. Isopropyl lauroyl sarcosinate (ILS), a derivative of a natural amino acid (sarcosine, also known as N-methylglycine) was introduced in this formulation in order to dissolve the oil-soluble UV absorbers and to photostabilize BMDM. The new sunscreen formulation obtained with this combination is photostable and contains a reduced amount of UV filters compared to other sunscreens with the same level of efficacy.ConclusionThis report described the steps resulting in the formulation of a new combination of UV filters in an oily emollient, which presents a high UVA-PF (UVA-PF = 38) and a SPF 50+, is photostable, and offers good protection against UV-induced biological damage.

Secondary Plant Metabolites for Sun Protective Cosmetics: From Pre-Selection to Product Formulation

“…Several vegetable oils have been proposed as photo-stability enhancers [92] and skin-friendly carriers by increasing the penetration of both synthetic and natural UV filters. Vegetable oils provide hydration to the sun-exposed skin and, in addition, can have an SPF themselves [93].…”

Allergic contact dermatitis caused by isopropyl lauroyl sarcosinate

“…Isopropyl lauroyl sarcosinate (glycine, N ‐methyl‐ N ‐[1‐oxododecyl]‐, 1‐methylethyl ester; CAS no. 230309‐38‐3; molecular weight, 313.48; Figure ) is used in oily vehicles to improve the solubility, efficacy and photostability of ultraviolet filters . According to the Household Products Database of the US National Library of Medicine, isopropyl lauroyl sarcosinate is present in 3 consumer products.…”

Photoprotection in changing times – UV filter efficacy and safety, sensitization processes and regulatory aspects

“…Due to the extension and multiplication of their chromophoric groups, the UVB filter ethylhexyl triazone (EHT), the UVB filter diethylhexyl butamido triazone (DEBT, iscotrizinol, Uvasorb HEB) and the broad‐spectrum UV filter bis‐ethylhexyloxyphenol methoxyphenyl triazine (BEMT, bemotrizinol, Tinosorb S) have a molecular weight well above 500 Da. These UV filters show comparatively high absorption coefficients, significant anti‐inflammatory effects and are highly efficient and very photostable . In addition, especially Tinosorb S can improve the photostability of other UV filter substances in a sunscreen .…”