FDA Approves Procysbi for Nephropathic Cystinosis

April 30, 2013

The US Food and Drug Administration (FDA) today approved a delayed-release version of cysteamine bitartrate (Procysbi, Raptor Pharmaceuticals) for a rare genetic disorder called nephropathic cystinosis, the agency announced.

Cystinosis, which affects roughly 500 patients in the United States, causes the amino acid cystine to accumulate in every cell of the body, leading to kidney problems and the loss of too much sugar, proteins, and salt through the urine. The most severe form of the condition, nephropathic cystinosis, stunts the growth of children and, if untreated, leads to complete kidney failure by roughly age 10 years, according to the National Institutes of Health.

The new therapy received orphan-product status from the FDA because it is designed to treat a rare condition. This designation confers economic benefits on the manufacturer that make commercializing a drug for a small number of patients more feasible.

The delayed-release version of cysteamine bitartrate, indicated for individuals 6 years of age and older, becomes the third FDA-approved drug to treat cystinosis. The other 2 are an immediate-release version of cysteamine bitartrate (Cystagon, Mylan) for nephropathic cystinosis, and cysteamine ophthalmic solution (Cystaran, Sigma-Tau Pharmaceutical), used to treat the build-up of cystine crystals in the eyes that occurs with adult onset of ocular, non-nephropathic cystinosis.

The immediate-release version of cysteamine bitartrate is taken around the clock every 6 hours. The delayed-release version is taken every 12 hours.

A study of 43 adults and children with nephropathic cystinosis showed that Procysbi controlled cystine levels just as well as Cystagon.

Nausea, bad breath, abdominal pain, and constipation number among the most common adverse events for cysteamine products, according to the FDA. More serious, but less common, adverse events include ulcers, altered mental states, and seizures.

More information about today's announcement is available on the FDA Web site.


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