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Influence of anatomical site and topical formulation on skin penetration of sunscreens

Authors Heather AE Benson, Vikram Sarveiya, Stacey Risk, Michael S Roberts

Published 15 October 2005 Volume 2005:1(3) Pages 209—218

Heather AE Benson1, Vikram Sarveiya2, Stacey Risk3, Michael S Roberts4

1Western Australian Biomedical Research Institute, School of Pharmacy, Curtin University of Technology, Perth, WA, Australia; 2Faculty of Pharmacy, University of Manitoba, Winnipeg, MB, Canada; 3HillTop Research Inc, Winnipeg, MB, Canada; 4Department of Medicine, University of Queensland, Princess Alexandra Hospital, Brisbane, QLD, Australia

Abstract: Sunscreen products are widely used to protect the skin from sun-related damage. Previous studies have shown that some sunscreen chemicals are absorbed across the skin to the systemic circulation. The current study shows that absorption into the skin of sunscreen chemicals applied to the face is up to four times greater than that of the same product applied to the back. This has implications for the way sunscreen products are formulated and may allow the use of less potent products on the face compared with the rest of the body. The effect of formulation vehicles on the release and skin penetration of the common sunscreen agent benzophenone-3 (common name oxybenzone) was also assessed. Penetration of benzophenone-3 across excised human epidermis and high-density polyethylene (HDPE) membrane was measured using in vitro Franz-type diffusion cells. Penetration and epidermal retention was measured following application of infinite and finite (epidermis only) doses of benzophenone-3 in five vehicles: liquid paraffin, coconut oil, 50:50 ethanol:coconut oil, aqueous cream BP, and oily cream BP. Highest benzophenone-3 skin retention was observed for the ethanol:coconut oil combination. Maximal and minimal benzophenone-3 fluxes were observed from liquid paraffin and coconut oil, respectively. The alcohol-based vehicle exhibited low benzophenone-3 release from the vehicle but high skin penetration and retention.

Keywords: sunscreen, skin penetration, vehicle effect, formulation, skin stripping

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