Sun-protection factor confounded by anti-inflammatory activity of sunscreen agents?

Autor: John C. Dowdy, Robert M. Sayre, E. William Rosenberg
Rok vydání: 2013
Předmět:
Zdroj: Journal of the American Academy of Dermatology. 69(3)
ISSN: 1097-6787
Popis: To the Editor: Recently 2 very interesting, stimulating articles about sunscreens appeared. The first from Ou-Yang et al reports sun-protection factors (SPFs) of 6 sunscreens, SPF 30 to 100, tested at 4 application rates from 0.5 to 2.0 mg/cm. They suggest that because sunscreen users may apply much less than the prescribed 2 mg/cm, SPFs as high as 100 are valuable because at 0.5 mg/cm at least SPF 30 protection remains. The other by Chouteau et al, testing both sunscreen products and active ingredients, reported that 13 of 21 showed antiinflammatory activity, including, interestingly, all ingredients in the SPF 100 products in the study of Ou-Yang et al. Table I shows sunscreen product amount applied over 0.5, 1, and 2 m body surface areas based on several of the application densities reported by Ou-Yang et al, and the corresponding topically applied amount of potential anti-inflammatory sunscreen agents. Because today’s sunscreen products are very water resistant, applied sunscreen is very efficiently absorbed into the body potentially at levels with pharmacologic significance. The SPF 100 products contained 5 sunscreens comprising 39% of their total weight, over half of which are salicylates, relatives of aspirin, reasonably expected to exhibit some degree of analogous antiinflammatory activity. Following this aspirin analogy, the amount of anti-inflammatory sunscreen agent applied to the skin is comparable to 2.5 to more than 40 tablets, not trivial levels of potent drugs. The sunscreens oxybenzone and dioxybenzone have in fact been patented as anti-inflammatory agents shown to be effective in attenuating ultraviolet-induced erythema when applied following exposure. In addition, several sunscreen agents were also reported as inhibiting the inflammatory mediator, inducible nitric oxide synthase. On the basis of these data, particularly that oxybenzone present in each of the products reported by Ou-Yang et al independently reduces ultraviolet erythema via anti-inflammatory mechanism(s) rather than the inherent optical attenuation of ultraviolet, the conclusions reached by Ou-Yang et al must be reconsidered. Robert M. Sayre, PhD, John C. Dowdy, PhD, and E. William Rosenberg, MD Rapid Precision Testing Laboratories, Cordova; Division of Dermatology, Department of Medicine, University of Tennessee Health Science Center, Memphis; and Department of Physics, University of Memphis
Databáze: OpenAIRE
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