ALPHA-HYDROXYACIDS MODULATE STRATUM-CORNEUM BARRIER FUNCTION

Alpha hydroxyacids (AHAs) are used to enhance stratum corneum desquama tion and improve skin appearance, The purpose of this study was to eva luate whether some AHAs improve skin barrier function and prevent skin irritation, Eleven healthy subjects (aged 28 +/- 6 gears, mean +/- SD ) entered the study. Six test sites of 8 x 5 cm (four different AHAs, vehicle only (VE) and untreated control (UNT)) were selected and rando mly rotated on the volar arm and forearm, The four different AHAs at 8 % concentration in base cream were glycolic acid (GA), lactic acid, ta rtaric acid (TA) and gluconolactone IGLU). The products were applied t wice a day for 4 weeks (2 mg/cm(2)). At week 4. a 5% sodium lauryl sul phate (SLS) challenge patch test was performed under occlusion for 6 h (HillTop chamber, 18 mm nide) on each site. Barrier function and skin irritation were evaluated by means of evaporimetry (Servomed EP-1) an d chromametry (a value, Minolta CR200) weekly, and at 0, 24 and 48 h after SLS patch removal, No significant differences in transepidermal water loss (TEWL) and erythema were observed between the four AHAs at week 4. After SLS challenge, GLU- and TA-treated sites resulted in sig nificantly lower TEWL compared with VE. UNT (P < 0.01) and GA (P < 0.0 5) both at 24 and 48 h. Similarly, a values were significantly reduce d after irritation in GLU- and TA-treated sites, This study shows that AHAs call modulate stratum corneum barrier function and prevent skin irritation: the effect is not equal for all AHAs, being more marked fo r the molecules characterized br antioxidant properties.