The mode of action of ethyl lactate as a treatment for acne.

We have shown that an alcoholic lotion containing ethyl lactate when applied topically to rat skin under occlusion became localized in the follicles and sebaceous glands. When applied to human facial skin the ethyl lactate was hydrolysed to ethanol and lactic acid, and thereby lowered the skin pH. Under such conditions the growth of recoverable skin bacteria, in particular the anaerobe Propionibacterium acnes, was inhibited, and the hydrolysis of sebum to free fatty acids by lipase derived from the bacteria was greatly impaired. These effects of ethyl lactate would account for its observed clinical efficacy in acne vulgaris.