Article

Human skin penetration of sunscreen nanoparticles: in-vitro assessment of a novel micronized zinc oxide formulation.

Therapeutics Research Unit, Southern Clinical Division, Department of Medicine, University of Queensland, Princess Alexandra Hospital, Woolloongabba, Australia.
Skin pharmacology and physiology (Impact Factor: 1.96). 02/2007; 20(3):148-54. DOI: 10.1159/000098701
Source: PubMed

ABSTRACT The extent to which topically applied solid nanoparticles can penetrate the stratum corneum and access the underlying viable epidermis and the rest of the body is a great potential safety concern. Therefore, human epidermal penetration of a novel, transparent, nanoparticulate zinc oxide sunscreen formulation was determined using Franz-type diffusion cells, 24-hour exposure and an electron microscopy to verify the location of nanoparticles in exposed membranes. Less than 0.03% of the applied zinc content penetrated the epidermis (not significantly more than the zinc detected in receptor phase following application of a placebo formulation). No particles could be detected in the lower stratum corneum or viable epidermis by electron microscopy, suggesting that minimal nanoparticle penetration occurs through the human epidermis.

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