Topical Stabilized Cysteamine as a New Treatment for Hyperpigmentation Disorders: Melasma, Post-Inflammatory Hyperpigmentation, and Lentigines

Cysteamine is an aminothiol naturally present in cells of the human body as an antioxidant resulting from the degradation of Coenzyme A. Physiologically it is well distributed in mammalian tissues. Highly concentrated in human milk, cysteamine acts as an intrinsic antioxidant and is known for its protective role. Multiple studies now document that cysteamine is a potent skin depigmenting agent. Historically, its rapid oxidation and very offensive odor made it difficult for topical use until recently when stabilization of cysteamine was achieved. This has led to an acceptable galenical form for topical application. Since 2015, the efficacy, safety, and tolerability of stabilized cysteamine (st.Cys) has been demonstrated in multiple clinical studies, as well a case reports. Stabilized cysteamine has demonstrated significant effectiveness for the treatment of melasma by two double-blind randomized and vehicle control trials. Stabilized cysteamine has shown to be as effective as well-known depigmenting therapies, including triple combination cream or tranexamic acid mesotherapy, with higher tolerability. A recent clinical trial has shown considerable efficacy of topical cysteamine for the treatment of senile lentigines, which are usually considered to be resistant to topical depigmenting agents. Topical stabilized cysteamine can be regarded to as one of the most potent treatments available for hyperpigmentation disorders in humans.