N acetyl glucosamine

N-acetyl glucosamine (NAG) is an amino sugar that is a precursor to hyaluronic acid and is found throughout nature and human tissues.

Its depigmenting ability originates from the inhibition of tyrosinase glycosylation, a step necessary in the production of melanin.

Glucosamine itself has been reported to decrease melanogenesis; however, formulating a topical agent has been difficult due to its instability. More recently, focus has now shifted to the development of NAG-containing cosmeceuticals given its greater stability, good skin penetration, and overall tolerability.

NAG is typically used in 2% concentrations as monotherapy or in combination with niacinamide, which may lead to a greater clinical effect given that there are two different mechanisms of depigmentation at work.

Multiple double-blind, controlled clinical trials have shown the safety and efficacy of NAG alone or NAG/niacinamide combination therapy to significantly lighten hyperpigmentation secondary to solar radiation in Caucasian and Japanese patients. NAG was generally well tolerated with mild-to-moderate skin irritation reported in a small number of patients. However, large clinical studies are still needed to determine the role of NAG in the management of PIH in all skin types.