KERATIN PEPTIDE HAND CREAM 101 Table I Skin and Phototype of the Volunteers Who Participated in the Study Volunteer Age Phototype Initial skin capacitance Kind of skin 24 IV 49.22 Hydrated 2 28 IV 32.33 Dry 3 45 III 34.57 Dry 4 30 III 47.22 Hydrated 5 29 V 59.55 Hydrated 6 26 III 51.00 Hydrated 7 38 IV 30.89 Dry 8 29 III 24.78 Dry 9 35 III 32.89 Dry 10 32 III 30.33 Dry 11 50 IV 29.56 Dry 12 28 IV 49.22 Hydrated 13 32 III 46.22 Hydrated 14 28 III 42.56 Dry 15 50 III 48.78 Hydrated 16 38 IV 42.22 Dry (Courage and Khazaka) using Mode 1, where the measurements are performed with a constant negative pressure. Results are visualized in a curve that points out the visco­ elastic qualities of the skin. The parameters that were considered in these studies are: RS, net elasticity, and R 7, the portion of elasticity compared to the complete curve (the closer to 1 these parameters are, the more elastic the skin is). All parameters were recorded in accordance with established guidelines (1-4). EFFECT OF KERATIN PEPTIDE HAND CREAM ON UNDISTURBED HAND SKIN A long-term study was performed to test the effect of the formulations when applied repeatedly to undisturbed hand skin. Baseline measurements ofTEWL, skin capacitance, and skin elasticity were taken on three marked zones of the dominant hand of the volunteers: two zones for topical treatment (base cream and cream containing 3% keratin peptide) and one untreated zone (control). Creams were randomly applied onto marked areas of 9 cm2. After 24 h, skin capacitance and skin elasticity were evaluated, and then the formulations were applied again. The application of the formulations was repeated once a day during two and a half weeks (not including weekend days) with a total of 12 applications, and parameters were measured after 24 h following each application. TEWL was measured on the three zones at the end of the treatment. During all the treatment period, hands were left air exposed and no restrictions on washing were done. EFFECT OF KERATIN PEPTIDE HAND CREAM ON SODIUM LAURYL SULPHATE (SLS) DISTURBED HAND SKIN A test was performed to evaluate the protective effect of the keratin cream applied to undisturbed hand skin followed by SLS exposure. Following the long-term study on undisturbed hand skin, baseline measurements of TRWL, skin raparitan,f', ;:incl skin elasticity were taken in the three treated areas of the dominant hand of the volunteers in group 2. The three zones were then exposed to 2 % SLS aqueous solution for 2 h (see

102 JOURNAL OF COSMETIC SCIENCE below), and the resultant irritation reaction was assessed after 2 h 30 min and 24 h after SLS exposure by measuring TEWL and skin capacitance (5-7). SLS exposure. Fifty microliters of an aqueous solution of 2% SLS was pipetted onto a layer of filter paper placed in each of several aluminum chambers (d = 12 mm, large Finn Chambers, Epitest Oy, Finland). The chambers were fixed to the skin for 2 h with adhesive tape. Upon the removal of the patch, the skin was gently rinsed with water and allowed to dry. DATA TREATMENT The mean values and standard deviations (SD) were calculated. Results were presented doubly evaluated as a percentage of modification with respect to the basal (initial) value and subsequently as a percentage of modification with respect to the control zone at the same time. Dixon's test was used for detecting outliers, which were excluded from the data. ANOV A variance analyses were used to determine significant differences between values obtained from different treatments (significance level accepted *p 0.05) using the Statgraphics® program. Statistics on the figures indicate the percentages (versus basal values) for the keratin peptide cream or the base cream treatments that are sig­ nificantly different from the percentages (versus basal values) obtained for the non­ treated control zone. RES UL TS AND DISCUSSION EFFECT OF KERATIN PEPTIDE HAND CREAM ON UNDISTURBED HAND SKIN A long-term study was performed to test the effect of the base hand cream formulation and the same formulation containing 3% keratin peptide. Evaluation of skin capacitance and elasticity was carried out 24 h after a daily application over two and a half weeks with a total of 12 applications, and TEWL was evaluated at the end of the treatment. Initial tests on the skin capacitance of the volunteers clearly showed that they fell into two categories. Nine volunteers had dry skin (mean initial capacitance less than 40 a.u.), and seven had hydrated skin (mean capacitance greater than 45 a.u.). This is an impor­ tant parameter in determining the efficacy of the keratin hand and nail cream, as will be discussed below. Transepidermal water loss, TEWL, is a sensitive index of skin barrier integrity. A lower % change in TEWL (measured as water loss in g/m2h) indicates the skin is acting more efficiently as a barrier to water loss and thus is better able to maintain its present moisture content. TEWL values before and after the treatment period for all 16 volun­ teers didn't show significant differences between the different treatments, indicating that for healthy skin in the absence of any disturbing treatment, variations in transep­ idermal water loss are too small to be taken into consideration. The test population was separated into two distinct groups to allow differences in TEWL to be observed. Although no significant results were found, evaluation of TEWL indi­ cated an influence of the keratin peptide cream for the group of volunteers with dry skin. A decrease in TEWL of 13 % relative to the control zone was observed for the cream containing keratin peptide (Figure 1).