ABSTRACT
BACKGROUND: Researchers have studied the water content at different skin depths. Since skin differs among tissue depth, we sought to determine the depth variability of the water content after moisturizing formulation application. Furthermore, we compared the effects of formulations with different type of manufacturing processes (hot and cold process). METHODS: To characterize the variations in the water content at different depths in the skin, measurements were done on the center of the inner forearm middle line of 18 sitting healthy women, before and after 1, 3, and 5 h of the application of two different moisturizing formulations (hot and cold process). Measurements included stratum corneum hydration via capacitance (SC) at 1.25 MHz (30-40 µm), and dermal water via tissue dielectric constant (TDC) at 300 MHz to depths of 500, 1500, and 2500 µm. RESULTS: There were significant differences between the SC mean values at all evaluated time intervals after application of both formulations when compared to baseline before application (T0). The SC mean values at 1 and 3 h are higher than those of the 5 h post application for both formulations. When comparing the formulations, hot formulation shows higher SC levels at 3 and 5 h, than cold formulation. TDC mean values to skin depths of 500 and 1500 µm increased after the application for both formulations. This increase was statistically significant at 1 and 3 h, when compared with T0. At 5 h no increases were seen in the TDC for any of the formulations. When comparing the mean values of each time evaluated, there is no statistically significant difference between the two formulations at depth of neither 500 µm nor 1500 µm. TDC mean value to a depth of 2500 µm does not increase after the application of any of the formulations. CONCLUSIONS: Hot and cold formulations are effective moisturizers; however, a distinct profile was obtained for each. When water content averages were compared, the effect of hot formulation in the superficial layers of the skin was greater and longer in time than those of the cold formulation. On the other hand, moisturizing formulations applied to the skin affected the dermis water content until depth of 1500 µm.
