Playtex In Vitro Sunscreen Test Predicts In Vivo UVA Protection, Firm Says
This article was originally published in The Rose Sheet
Executive Summary
A test developed by Playtex to measure sunscreens' UVA protection in vitro could be used as a preliminary step before in vivo testing, Playtex Sun Care Principal Scientist Olga Dueva, PhD, stated Dec. 5 at the Society of Cosmetic Chemists annual scientific meeting in New York City
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A test developed by Playtex to measure sunscreens' UVA protection in vitro could be used as a preliminary step before in vivo testing, Playtex Sun Care Principal Scientist Olga Dueva, PhD, stated Dec. 5 at the Society of Cosmetic Chemists annual scientific meeting in New York City. Ongoing studies conducted by Playtex have shown "excellent correlation" between the new in vitro method and in vivo testing that measures protection from UVA rays, Dueva said. To date, the firm has evaluated 15 sunscreens ranging from SPF 20 to SPF 50. In addition to providing a predictive measure, the in vivo test could potentially replace the standard in vitro test currently used by manufacturers, she added. In vivo testing is generally conducted using the Japanese Cosmetic Industry Association method, which measures protection factor A by comparing persistent pigment darkening in skin with and without sunscreen protection, Dueva said. UVA exposure time is based on an estimated range of PFA values determined in vitro prior to in vivo testing, making correct in vitro results essential to the accuracy of the human test, the researcher noted. The Playtex method may help ensure accuracy in both assays, she said. The test is based on a four-step process; first, in vivo SPF is identified in at least five panels. In vitro SPF based on sunscreen's absorbance spectrum in the UV region is then determined by applying 2 mg/sq. cm of sunscreen on Vitro-Skin , a substrate. The absorbance spectrum is adjusted if the two measurements differ. The final step is calculation of PFA in vitro using the integration area of the adjusted spectrum in the UVA1 region, an irradiation spectrum of a 150 watt xenon arc lamp with 2 mm WG355 and 1 mm UG11 filters and the PPD spectrum. A retrospective analysis utilizing results of a Cosmetic, Toiletry and Fragrance Association round-robin study of seven sunscreens confirmed Playtex' results, Dueva noted. Playtex has provided the test method to several other manufacturers and has submitted it to CTFA for consideration, according to the company. Currently, there is no FDA-approved method for determining UVA protection. However, the agency stayed the OTC Sunscreen Drug Products Final Monograph earlier this year to develop UVA testing and labeling requirements (1 (Also see "Skin Protectant Final Rule Allows Cross-Monograph Ingredient Combinations" - HBW Insight, 9 Jun, 2003.), p. 3). |