EFFECT OF BARRIER CREAMS - HUMAN SKIN IN-VIVO

An in vivo method was developed to measure the effectiveness of skin p rotective creams against 2 dye indicator solutions: methylene blue in water and oil red O in ethanol, representative of model hydrophilic an d lipophilic compounds. 3 representative barrier creams commercialized as effective against lipophilic, hydrophilic, or lipophilic and hydro philic substances were assayed by measurements of the dye in cyanoacry late strips of protected skin samples after various application times. The flexural surfaces of the forearms of 6 normal volunteers (3 femal e and 3 male, mean age 26.8+/-4.1 years) were treated. The method was as follows: solutions of 5% methylene blue in water and 5% oil red O i n ethanol were prepared, and applied to untreated skin and protective- cream-pretreated skin with the aid of aluminum occlusive chambers, for O h and 4 h, respectively. At the end of the application time, the cr eams were removed. Consecutive skin surface biopsies (SSB) from 1 to 4 strips were taken. The amount of stain in each strip was determined b y colorimetry, and the cumulative amount of stain from 1 to 4 strips i n each measurement was calculated. The cumulative amount represents th e amount of permeation of each solution at each time point, and the ef ficacy of skin barrier cream. The results showed one formulation at bo th O h and 4 h reduced the amount of permeation of methylene blue (p<0 .01) and oil red O (p<0.01) compared with the control group. Another f ormulation was protective against the permeation of oil red O (p<0.01) , but not against methylene blue at 0 h and 4 h; it was not significan tly different at O h versus 4 h. The 3rd formulation produced increase d cumulative amounts to oil red O at both O h and 4 h (p<0.05); it als o increased permeation amounts to methylene blue (p<0.05) after 4 h. T his model appears a facile, rapid and objective early screen to evalua te the efficacy of skin barrier creams in vivo, as well as their indiv idual ingredients. (C) Munksgaard, 1996.