Pharmacology
People with cystinosis lack a functioning transporter (cystinosin) which transports cystine from the lysosome to the cytosol. This ultimately leads to buildup of cystine in lysosomes, where it crystallizes and damages cells. Cysteamine enters lysosomes and converts cystine into cysteine and cysteine-cysteamine mixed disulfide, both of which can exit the lysosome. Biological function
Cysteamine also promotes the transport of L-cysteine into cells, that can be further used to synthesize glutathione, which is one of the most potent intracellular antioxidants.Cysteamine is used as a drug for the treatment of cystinosis; it removes cystine that builds up in cells of people with the disease. History
First evidence regarding the therapeutic effect of cysteamine on cystinosis dates back to 1950s. Cysteamine was first approved as a drug for cystinosis in the US in 1994. An extended release form was approved in 2013. Society and culture
It is approved by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA).In 2013, the regular capsule of cysteamine cost about $8,000 per year; the extended release form that was introduced that year was priced at $250,000 per year.
Cysteamine is a chemical compound that can be biosynthesized in mammals, including humans, by the degradation of coenzyme A. The intermediate pantetheine is broken down into cysteamine and pantothenic acid. It is the biosynthetic precursor to the neurotransmitter hypotaurine.It is a stable aminothiol, i.e., an organic compound containing both an amine and a thiol functional groups. Cysteamine is a white, water-soluble solid. It is often used as salts of the ammonium derivative [HSCH2CH2NH3]+ including the hydrochloride, phosphocysteamine, and bitartrate.As a medication, cysteamine, sold under the brand name Cystagon among others, is indicated to treat cystinosis. Medical uses
Cysteamine is used to treat cystinosis. It is available by mouth (capsule and extended release capsule) and in eye drops.When applied topically it can scavenge free radicals and lighten skin thats been darkened as a result of post-inflammatory hyperpigmentation, sun exposure and Melasma. Tentative evidence suggests that it may be a more effective depigmentation agent than hydroquinone, retinoids and topical corticosteroids in individuals with chronic skin discoloration. Topical application of cysteamine cream has also demonstrated similar efficacy to intradermal tranexamic acid injections for the treatment of Melasma but with much fewer adverse effects. Adverse effects
Topical use
The most important adverse effect related to topical use might be skin irritation. However its significantly better tolerated than alternative skin lightening treatments with similar efficacy.