Cutaneous Irritation to Alpha Hydroxy Acids in Normal Human Skin / 대한피부과학회지

ABSTRACT

BACKGROUND: Alpha hydroxy acids (AHAs) are known to diminish corneocyte cohesion at the innermost levels of the stratum corneum and have been used in the treatment of various disorders of keratinization. However, their effect on skin barrier function and their irritant potential is not fully understood. OBJECTIVE: Our study was done to evaluate the skin irritancy of AHAs in normal human skin. METHODS: Patches with 1%, 5% and 10% solutions of lactic acid (LA) and glycolic acid (GA) were applied to the volar forearm of 20 healthy volunteers for 24 hours using large Finn chambers with filter paper. Visual scores, erythema (E-) index and transepidermal water loss (TEWL) were measured at 30 min, 24 h and 48 h after removal of the patches. RESULTS: The results are summarized as follows. 1. Visual scores were 0.1+/-0.3 (1%), 0.5+/-0.6 (5%) and 1.1+/-0.8 (10%) at 24 h after removal of LA, and were 0.2+/-0.4 (1%), 0.6+/-0.6 (5%) and 1.0+/-0.7 (10%) at 24 h after removal of GA. They were increased in proportion to the concentrations and there were significant differences in skin responses between the control and each concentration of the solutions. 2. E-indices were 9.1+/-2.1 (control), 8.8+/-1.8 (1%), 9.0+/-2.6 (5%) and 10.5+/-3.9 (10%) at 24 h after removal of LA, and were 9.4+/-1.8 (control), 9.3+/-2.3 (1%), 10.0+/-3.0 (5%) and 11.1+/-3.5 (10%) at 24 h after removal of GA. They were not increased in the patch areas of 1% and 5% solutions in both the LA and GA group, but were significantly increased in the patch areas of 10% solutions in both the LA and GA group. 3. TEWL values were 7.3+/-2.3 (control), 8.3+/-4.0 (1%), 9.8+/-4.5 (5%) and 16.7+/-9.1 (10%) at 24 h after removal of LA, and were 8.1+/-3.2 (control), 7.8+/-3.8 (1%), 8.6+/-3.0 (5%) and 10.9+/-4.1 (10%) at 24 h after removal of GA. They were not increased in the patch areas of 1% LA, 1% GA and 5% LA, but there were high significant differences between the controls and 10% solutions of both LA and GA. CONCLUSION: Visual scores were increased in all concentrations of AHAs tested, but the increase in E-index and TEWL values were not significant or minimal in 1% and 5% solutions of AHAs. These findings suggest that AHAs could be classified as non-corrosive irritants.