MOISTURIZING EFFECT OF TOPICAL COSMETIC PRODUCTS 337 intervals of hours 1, 25, and 26 ( p 0.02) as well as 24 ( p 0.006). In contrast, Allpresan® showed signifi cant improvement in hydration ( p 0.003) only after 24 h of the applica- tion. Regarding support of the protective barrier function of the skin presented through TEWL values, this was confi rmed to be signifi cant for Eucerin® after 1 h of application ( p 0.005), as well as the 4th and 25th h ( p 0.001) of application, whereas for Allpresan®, it was after the 1st ( p 0.002), 2nd ( p 0.001), 4th ( p 6.23 × 10 −6 ), 24th ( p 2.36 × 10−8), and 25th h ( p 4.53 × 10−9). This suggests that Eucerin® tends to possess moistur- izing effects, whereas Allpresan® favors barrier function. THE EFFECT OF PERIOD OF CREAM ACTION AND UREA CONTENT ON THE PARAMETERS OF THE SKIN Contour models were constructed to present the synergistic effect of CP action time (A factor) and urea content (B factor) on the skin parameters monitored (hydration, TEWL). Figure 5 shows the effect of A factor and B factor on skin hydration. The slope of contour lines in both graphs makes clear that both these factors observed are equally important. For Eucerin® (Fig. 5A), maximum hydration (51.6 c.j.) was measured at the beginning of the test (1 h) with maximum urea content (10%). Hydration gradually decreased over time to approximately 1.0 c.j. after 26 h of exposure to the cream at zero urea content. The model, however, suggests hydration can be increased signifi cantly even after 25 h of exposure to the cream by adding urea upon 10% addition of urea, hydration increases up to 16.3 c.j. For Allpresan® (Fig. 5B), the maximum value of hydration (23.0 c.j.) occurred at the beginning of the test (1 h) with maximum urea content (10%). Hydration during the fi rst 15 h of action of Allpresan® is approximately twice as low as for Eucerin®, the hydration values being about the same for both CPs after 20 or more hours of action. One should not forget the infl uence of the foam’s urea content on the effect of hydration at the end of the test (hour 25) a 10% addition of urea increases hydration up to about 15.3 c.j. Hydration is affected greatly by glycerol content. The differences between hydration value of both CPs at the beginning of the test, 51.6 c.j. (Eucerin) vs 23 c.j. (Allpresan), can be attributed to a difference in glycerol content in CPs. Relative concentration of urea Figure 5. Model dependence of skin hydration on CP action time and urea content. (A) Eucerin® (B) Allpresan®
JOURNAL OF COSMETIC SCIENCE 338 and glycerol in the compared CPs is not known. Nevertheless, according to INCI, Eu- cerin contains (Table I) more glycerol than urea Allpresan contains less glycerol than urea. Figure 6 presents a simulation of the infl uence of A factor and B factor on TEWL. Trends in TEWL development for Eucerin® (Fig. 6A) are equal to those of Allpresan® (Fig. 6B), the difference between the values of the two products being small, whereas that between the minimum and maximum values is approximately twice. At zero urea content and 1 h of action of the products, TEWL is about 13.0 g/m2/h. Lower TEWL values ( 10.0 g/m2/ h1) are evident at the addition of more urea (above 6%) and, in fact, are not much affected by the duration of action of the preparations, and at additions of urea less than 6% and with the duration of the creams’ action exceeding 15 h. At maximum addition of urea and 1 h of action of the CP, TEWL equals approximately 8.0 g/m2/h1. The lowest TEWL was recorded for both forms of application at zero addition of urea after 26 h of action of these. CONCLUSION Diabetes affects some functional properties of the epidermis and dermis and may be re- sponsible for a number of skin complaints associated with the disease. Using CPs of proper composition can prevent possible complications like these. Skin care has positive effects on the overall condition of the skin and is one of the fundamental preventative routines of diabetic patients, thereby contributing to the improved quality of their lives. The instrumental techniques used permit, via identifi cation of the selected characteristics of the skin’s surface, an appropriate description of the level of hydration effects of the tested commercially available CPs designed for the care of diabetic foot. The level of hy- dration effect is strongly dependent on the formulation of the product. Even a single ap- plication of a CP can induce a temporary regenerative effect in relation to selected characteristics of the skin’s surface. Although the observed hydration effect of each CP was similar, comparing the tested CPs (Beline®, Ziaja®, Eucerin®, Allpresan®, DiabeCare®, and Scholl®) containing effective humectants against the ointment base in which any mois- turizing substances were absent. This occurred after application of these at monitored time Figure 6. Model dependence of TEWL on CP action time and urea content. (A) Eucerin® (B) Allpresan®
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