Comparative in vivo study of the efficacy and tolerance of exfoliating agents using reflectance spectrophotometric methods.

The aim of the present study was to compare the effectiveness and the safety of different topical agents (glycolic acid, mandelic acid, and grape juice acid mixture) in skin exfoliation by objective instrumental methods. To evaluate the exfoliating effects of these substances, a new experimental in vivo protocol based on DHA (dihydroxyacetone)-induced skin pigmentation was used. Skin acceptability towards acid application was investigated by the evaluation of skin erythema induced by topical application of these substances at increased concentrations. Furthermore, their photosensitizing effects were evaluated by determining the increase in sensitivity to UV-light exposure in cutaneous sites previously treated with acids. These in vivo evaluations were monitored by reflectance spectophotometry. From the results obtained, we observed the differing capacities of the tested acids to increase the rate of skin regeneration, with a significant reduction in the time required to obtain skin renewal. The study pointed out that glycolic acid (10% w/w) induced a faster skin exfoliation, a more intense erythema, and a higher photosensitizing effect in comparison with the mandelic acid and grape juice acid mixtures. Further evidence showed that the mandelic acid and grape juice acid mixtures were able to induce a slower and safer peeling action in comparison with glycolic acid. Finally, our results suggest that the methodologies and protocols used in this study may help in choosing the most appropriate topical agents for skin exfoliating treatments.