A 10% Lactobionic acid-containing moisturizer reduces skin surface pH without irritation—An in vivo/in vitro study

Abstract

Background/Objectives: Stratum corneum acidification is a newer strategy in management of inflammatory dermatoses; acidifying emollients are normally used for that purpose. However, a decrease in pH of the skin is commonly connected to an increase in irritation. The aim of this study was to investigate whether lactobionic acid (LA), cosmeceutical active and "superacid" belonging to the class of alpha-hydroxy acids (AHAs), could decrease pH of skin surface without irritation. Methods: Safety profile of emulsion based on alkyl polyglucosides (APGs) sugar emulsifiers with 10% LA was evaluated in vitro (acute skin irritation test using cytotoxicity assay), and in vivo in safety study employing measurements of the relevant biophysical human skin parameters upon cessation of 24 hours occlusive treatment: transepidermal water loss (TEWL), stratum corneum hydration (SCH), and skin erythema index (EI). The effect on the pH of human skin surface was investigated by pH measurements prior and 1 hour after application of the emulsion with 10% LA. Results: The pH of the skin was significantly reduced after application of LA-containing emulsion. The results for in vitro skin irritation potential assessment were in line with the in vivo safety study, indicating a satisfactory safety profile of both APG-based emulsion vehicle per se and emulsion with 10% LA. Conclusion: Lactobionic acid (10%) in emulsion based on APGs reduces skin surface pH without irritation and skin barrier impairment; it could be proposed as an alternative to low-molecular AHAs in acidifying emollients.