PRIME Journal Vol. 9 Issue 5

CYSTEAMINE FORTREATING HYPERPIGMENTATION Dr JenniferDavid discusses theuseof cysteamine5%as anovel first line non‑hydroquinone treatment optionbridging that gapbetweensafetyand efficacy in treatinghyperpigmentation ABSTRACT The unmet needs for a safe and effective depigmentation agent are very significant worldwide, particularly in our skin of colour patients. Concerns are most common in these populations, yet safe and effective treatment modalities are lacking to them. 5% cysteamine can be used to reduce discolouration, even skin tone, and improve overall complexion, particularly for skin of colour patients. The physiologic activity of cysteamine in skin pigmentation was discovered in 1966 by Professor Chavin, a researcher of the American Museum of Natural History, while studying the skin of goldfish. Learning about these results, Drs Fitzpatrick, Frenk, Pathak, Bleehen, the grandfathers of pigmentation research, investigated the depigmenting effectiveness of cysteamine and observed in 1968 that cysteaminewas significantly stronger than hydroquinone in vivo . However, the instability and skunky odour of cysteamine prohibited its formulation as a topical treatment, until 50 years later when a providential laboratory accident lead to a dramatic improvement in its stability and odour. Cysteamine was now usable in a 5% topical formulation. A case series presented at the AAD 2013 validated its potent action in human and subsequent high standard clinical trials confirmed its significant pigment correction effectiveness. Emerging results of the clinical efficacy, safety, and tolerability of cysteamine 5% are making it a very interesting first line non-hydroquinone treatment for melasma and other hyperpigmentation concerns. D ISORDERSOFHYPERPIGMENTATION, most notably melasma and post- inflammatory hyperpigmentation, afflict a great deal of psychological stress on patients and remain a top concern at dermatology office visits 1 . These disorders also have a disproportionately higher rate of occurrence in the skin of colour population, which include those of African, Asian/Pacific Islander, Caribbean, Indian, Middle Eastern, and/or Latino descent. While the current cosmetic market is flooded with treatment options, most available products either lack efficacy or have a safety profile with a less than favourable risk/benefit ratio. Adverse events and drawbacks such as exogenous ochronosis, skin atrophy, photosensitivity, post-inflammatory hyperpigmentation and worsened hyperpigmentation have created a very large unmet need for a product that is both safe and effective 1–4 . Hydroquinone has remained the gold standard amongst topical bleaching creams in the United States despite controversies regarding its safety profile. While the increased risk of renal carcinoma noted in rodent models taking oral hydroquinone was never directly correlated to topical human consumption, this along with the risk of exogenous ochronosiswas enough to generate awarning report from theWorld Health Organisation (WHO) in 1997 and to implement a ban and strict regulation for the use of hydroquinone in Europe, Japan and a number of other countries in the early 2000s 5,6 . Innovative approaches for treating hyperpigmentation started centuries ago, and a variety of agents were utilized to lighten disfiguring hyperpigmentation, including applications of borax, sulfur, tincture of iodine, potassium and sodium hydroxide, and ammoniated mercury. Prepared in complex formulations, they proved to be highly poisonous, and many produced rapid desquamation of the epidermis 7,8 . Intensive research on depigmenting agents in the 1960s led to the discovery and first clinical evidence of a molecule that was safe in mammals yet effective in inhibiting melanogenesis. The discovery of the physiologic activity of cysteamine in skin pigmentation Professor Chavin was a researcher of the American Museum of Natural History studying fish physiology. In the 1960’s he became curious about the metabolic functions of cysteamine, a natural antioxidant, in fishes. For one of his experiments, investigating the physiology of fish colouration, he injected cysteamine into the skin of a black goldfish. The goldfish scales changed from KEYWORDS Cysteamine 5%, melasma, hyperpigmentation, post-inflammatory hyperpigmentation, skin of colour JENNIFER DAVID, DO, MBA is a board-certified dermatologist specialising in general dermatology, cosmetic dermatology, and skin of colour dermatology, at Schweiger Dermatology Group, Philadelphia PA, USA email COVER STORY | HYPERPIGMENTATION | CLINICAL FEATURE | September/October 2019 25