Which medications in the drug class Cystine-lowering Agents are used in the treatment of Fanconi Syndrome?

Updated: Feb 09, 2018
  • Author: Sahar Fathallah-Shaykh, MD; Chief Editor: Craig B Langman, MD  more...
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Cystine-lowering Agents

Numerous compounds have been found to decrease the levels of cystine in cultured cells, but only a few were proven effective in clinical trials. Prominent among the effective drugs is cysteamine, which has been shown to decrease the tissue levels of cystine, delay the progression of renal disease, and improve linear growth, particularly when treatment is started in children younger than 2 years. However, no effect on the Fanconi syndrome was documented. Cysteamine bitartrate (Procysbi), a delayed-release formula that can be given every 12 hours, is approved by the US Food and Drug Administration (FDA) for management of nephropathic cystinosis in children aged 1 year and older and adults. A randomized controlled crossover trial showed the delayed-release product was safe and effective in reducing WBC cystine levels in patients with cystinosis. [22]  Approval for children as young as 1 year is based on a long-term, prospective, open-label study that enrolled 17 people living with nephropathic cystinosis, including 15 children between the ages of 1 and 5 years old, who had not previously been treated with cysteamine therapy. Children enrolled in the study experienced lowering of white blood cell (WBC) cystine levels from poor controlled to well controlled at 12 and 18 month measurements. Additionally, they experienced measured improvements in growth milestones including weight and height. [23]

Cysteamine bitartrate (Procysbi)

Cysteamine bitartrate is used off-label to reduce cystine levels, potentially delaying kidney and other damage associated with Fanconi syndrome. The delayed-release product is used in the management of nephropathic cystinosis, a rare genetic condition, in adults and children aged 1 year or older. It was granted an orphan product designation.

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