FDA Approves Procysbi
FDA Approves Procysbi For Rare Genetic Disorder
In April 2013, Procysbi was FDA approved as an orphan drug for the treatment of nephropathic cystinosis. Cystinosis affects only roughly 500 patients in the United States. The disorder 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.
Currently the FDA approved drugs used to treat cystinosis include Cystagon (cysteamine bitartrate), an immediate-release tablet that was approved in 1994, and Cystaran (cysteamine ophthalmic solution) eye drops, approved last year to treat corneal cystine crystal accumulation. Procysbi is a delayed-release capsule intended for patients ages 6 years and older. While Cystagon is taken every six hours around the clock to control cystine levels, Procysbi is a long-acting formulation that is taken every 12 hours.
The major study supporting Procysbi’s safety and effectiveness involved 43 adult and pediatric patients with nephropathic cystinosis. Patients were randomly assigned to receive Cystagon or Procysbi for three weeks before being switched to the other product for an additional three weeks. Blood testing showed Procysbi was as effective as Cystagon in controlling cystine levels.
The most common side effects in patients treated with cysteamine products include nausea, bad breath, abdominal pain, constipation, indigestion or upset stomach, headache, drowsiness and dizziness. Other uncommon but serious side effects include ulcers or bleeding of the stomach or intestine, altered mental state, seizures, severe skin rashes and allergic reactions.
The maintenance dose of Procysbi is 1.3 gram/m2/day, in two divided doses every 12 hours. For a 50 lb child that is approximately 600 mg every 12 hours. The capsules are available in 25mg and 75 mg doses. AWP for 250 pills of the 75mg capsules is $18,675. That would cover approximately 2 weeks of therapy for the 50 lb child.