N-acetyl-4-S-cysteaminylphenol as a new type of depigmenting agent for the melanoderma of patients with melasma.
METHODS
--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.
Jimbow
K
K
Division of Dermatology and Cutaneous Sciences, Faculty of Medicine, University of Alberta, Edmonton, Canada.
D000328:Adult; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D003543:Cysteamine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008297:Male; D008548:Melanosis / Q000150:complications / Q000188:drug therapy* / Q000473:pathology; D008854:Microscopy, Electron; D008875:Middle Aged; D012880:Skin Pigmentation / Q000187:drug effects
D000970:Antineoplastic Agents; D003543:Cysteamine; C043037:4-S-cysteaminylphenol