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October 1991

N-Acetyl-4-S-Cysteaminylphenol as a New Type of Depigmenting Agent for the Melanoderma of Patients With Melasma

Author Affiliations

From the Division of Dermatology and Cutaneous Sciences, Faculty of Medicine, University of Alberta, Edmonton.

Arch Dermatol. 1991;127(10):1528-1534. doi:10.1001/archderm.1991.01680090092011

• Background and Design.—  Melasma is a difficult medical problem to treat. Hydroquinone is administered to many patients, but it is unstable and local irritation and dermatitis may develop after a prolonged use at a high concentration. This study introduces a new depigmenting agent, N-acetyl-4-S-cysteaminylphenol, for better management of melanoderma in patients with melasma.

Results.—  Our study, based on a retrospective observation of 12 patients using 4% N-acetyl-4-S-cysteaminylphenol in oil-in-water emulsion, showed a complete loss (8%), a marked improvement (66%), or a moderate improvement (25%) of melasma lesions. Visible changes of melanoderma can be seen in 2 to 4 weeks after daily topical application. This depigmentation was associated with a decrease in the number of functioning melanocytes and in the number of melanosomes transferred to keratinocytes. N-acetyl-4-S-cysteaminylphenol is the tyrosinase substrate, and, on exposure to tyrosinase, it formed a melanin-like pigment.

Conclusions.—  A phenolic thioether, N-acetyl-4-S-cysteaminylphenol, is a new type of depigmenting agent for the better management of melasma. It is much more stable and less irritating to the skin than hydroquinone, and it is specific to melanin-synthesizing cells.(Arch Dermatol. 1991;127:1528-1534)

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