Lactic AcidvsPanthenol (Pro-Vitamin B5)

Lactic acid (90 Da, larger than glycolic acid) exfoliates via the standard AHA mechanism: chelating calcium at corneodesmosomes and promoting desquamation through protease activation. Unlike glycolic acid, lactic acid is a natural component of the skin's natural moisturizing factor (NMF) and functions as a humectant, drawing water into the stratum corneum through hygroscopic binding. It inhibits tyrosinase enzyme activity in melanocytes, providing mild brightening. At higher concentrations (10%+), lactic acid upregulates serine palmitoyltransferase and glucosylceramide synthase in keratinocytes, stimulating ceramide synthesis and improving barrier lipid composition. It also enhances filaggrin proteolysis to NMF components. This dual action—exfoliation plus barrier support—makes it the most moisturizing AHA and clinically useful for dry, sensitive, or barrier-compromised skin.

Panthenol (D-pantothenic acid alcohol) penetrates the stratum corneum and is converted to pantothenic acid (vitamin B5) by pantetheinase and alkaline phosphatase enzymes in the skin. Pantothenic acid is a precursor to coenzyme A (CoA), which is required for the synthesis of fatty acids (via acetyl-CoA carboxylase and fatty acid synthase) that form the ceramides, cholesterol, and free fatty acids of the stratum corneum lipid barrier. This supports barrier repair, improves lamellar structure, and reduces transepidermal water loss (TEWL). Panthenol has direct humectant properties—its hydroxyl groups attract and bind water in the stratum corneum. It stimulates fibroblast proliferation and migration, accelerating wound healing and re-epithelialization. Panthenol may also have mild anti-inflammatory effects. As a provitamin, it is stable in formulations and well-tolerated. The Bepanthen/Bepanthol healing creams leverage these mechanisms for wound care and barrier repair.