Figure 7. Single applications of either polyhydroxyl acids decrease SC pH and accelerate barrier recovery in lightly pigmented subjects.
(a–c) Lactobionic acid (LBA, 5% in propylene glycol/ethanol: 70/30), gluconolactone (GL), neutralized LBA, neutralized GL, or vehicle (V) was applied on the forearm skin of human volunteers (n = 16). Although basal values were identical on all test sites before application (not shown), significant decreases in surface pH were observed at 1, 6, and 24 hours following single application of either LBA or GL acids compared with the vehicle. (d) TEWL was measured before and at 0, 3, 24, and 48 hours following acute barrier disruption by repeated cellophane tape stripping on the forearms of type I–II subjects. Acidification of SC pH by PHA (LBA or GL, n = 16) significantly improved barrier recovery in comparison with vehicle (neutralized LBA/neutralized GL)-treated skin sites.