Characterization of the efficacy of a moisturizer that restores the cutaneous barrier

The high incidence of xerosis amongst the population is a factor that contributes to the high usage of moisturizers. Additionally, different types of cosmetic products include this claim in the labelling. Numerous strategies have been developed to assess the efficacy of moisturizers, however most of these methodologies are based in methods that can be influenced by the water that exists in the formulation and only provide instantaneous data. The aim of this study was to characterize the effect of a moisturizer on stratum corneum hydration and skin barrier function by two approaches that challenge the barrier: the assessment of the permeation of a vasodilating molecule and the assessment of the protection against irritation by sodium lauryl sulphate (SLS). The results obtained by these methodologies were then compared with those obtained with more conventional approaches. 15 healthy volunteers applied a formulation for two weeks, twice daily, on a marked site on the lower leg. Different measurements were then conducted in all volunteers. In the methodology that assesses changes in the permeation, ethyl nicotinate application was followed by measurements with laser Doppler flowmetry (LDF). The more conventional approaches were measurements of transepidermal water loss (TEWL) and skin hydration. Finally, to assess the protective properties, a 2.5% SLS solution was applied for 24h to a treated and untreated site, followed by measurements of TEWL and erythema. Results indicate that the formulation was able to cause positive changes to the barrier and skin hydration. The study was also able to demonstrate the advantages of using methodologies that challenge the skin, over the more conventional approaches