METHOD TO STUDY SKIN MOISTURIZERS 267 .-, 80[ 6o = 40 m 20 (J 0 Formulations mE [] E+A [] E+E [] E+C mControl Figure 2. Mean values of the capacitance data of the stratum corneum 30 days after using the studied formulations. E = emulsion (base formulation) E + A = emulsion + vitamin A palmitate E + E = emulsion + vitamin E acetate E + C = emulsion + ceramide III. The values indicate means _+ standard deviation, where the replicate number is n = 8. palmitate, vitamin E acetate, and ceramide III behaved in a statistically similar way, and the presence or not of these active substances in the base formulation presented no statistical difference for the hydration of the stratum corneum. Thus, the studied for- mulations at the concentrations and period analyzed were not effective in the hydration of the stratum corneum. The cosmetic raw material market has types of ceramides such as ceramide II and ceramide III in different concentrations. The suppliers suggest using ceramide II in concentrations between 0.2% and 1.0% and concentrations between 0.05% and 0.5% for ceramide III. Moreover, these can be prescribed by dermatologists in different con- centrations in agreement with the patient's need. The concentration of ceramide III of 0.1% was within the recommended amount, and was a balance between cost and benefit. In regard to the vitamin A palmitate, Maia Campos and collaborators observed an increase in the intra- and extracellular hydration in the deeper layers of the epidermis (7). However, the results of our study cannot be compared with those obtained by Maia Campos et al., because the capacitance method did not allow us to measure the vitamin A palmitate hydration properties on the skin surface. Likewise, the capacitance method was not appropriate to evaluate the expected moisturizing effort of the 2% vitamin E acetate, known for its beneficial hydration effects. Considering the hydration effects observed for the three active-enriched formulations, there were no differences from the formulation without it, suggesting that the concen- tration of moisturizing raw materials in the formulation used as a vehicle masked the moisturizing property of the vitamin A, vitamin E, and ceramide IIl when used at the concentrations evaluated. The non-invasive capacitance method was also utilized by L6den and Lindeberg (17) to evaluate the hydration effect of different topical formulations. They documented that the emulsions of interest increased the capacitance of the stratum corneum in a similar manner. AccoMing to them, the presence of different active ingredients (glycerine, pyrollidone carboxylic acid, and urea) does not significantly alter skin capacitance, thus suggesting that non-absorbed components influence the capacitance values. Therefore, electrical measurement, such as the capacitance method, used to evaluate skin moisture is not sufficiently appropriate to determine the effect of moisturizer cosmetic

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