In vitro skin permeation and retention of parabens from cosmetic formulations

Parabens are antimicrobial agents widely used in foods, cosmetics and pharmaceutical products. Although non-mutagenic, non-teratogenic and non-carcinogenic, parabens can induce allergic contact dermatitis and posses estrogenic activity. The aim of this work was to assess the skin permeation and retention of methyl- (MP), ethyl- (EP) and propyl- (PP) paraben from three commercial cosmetic creams. The results obtained indicate that parabens are capable of permeating through and accumulating in the skin. The extent of penetration depends more on paraben characteristics (solubility, lipophilicity) than on the composition of the formulation. In particular, the percentage permeated across the skin was independent of the composition of the cream used and decreased in the order MP, EP and PP, in accordance with decreasing solubility. After 8 h of contact with the skin, 60% of MP, 40% of EP and 20% of PP were found across the skin. Concerning skin retention, the percentage remaining in the skin after 8 h depends on both paraben characteristics and on the composition of the formulation used. In conclusion, it appears that only the type of paraben, in particular its water solubility, affects skin penetration whereas the composition of the emulsion, which influences skin retention, plays a secondary role. Finally, excised rabbit ear skin can be considered as a good model for human skin for in vitro experiments.