Use of Cysteamine in the Treatment of Cystinosis

Overview

Cystinosis is an inherited disease resulting in poor growth and kidney failure. There is no known cure for cystinosis, although kidney transplantation may help the renal failure and prolong survival. Both the kidney damage and growth failure are thought to be due to the accumulation of the amino acid cystine within the cells of the body. The cystine storage later damages other organs besides the kidneys, including the thyroid gland, pancreas, eyes, and muscle. The drug cysteamine (Cystagon; ProCysBi) is an oral medication given to patients with cystinosis prior to kidney transplantation. The drug works by reducing the level of cystine in the white blood cells and muscle tissue. The drug may also decrease levels of cystine in the kidneys and other tissues. This study has several goals: 1. Long-term surveillance of cysteamine treated patients. 2. Detection of new non-kidney complications of cystinosis. 3. Maintenance of a patient population for genetic testing (mutational analysis) of the cystinosis gene.\<TAB\>

Patients with nephropathic cystinosis have been treated with the cystine-depleting agent cysteamine since 1978. This therapy prevents or delays renal deterioration, improves growth, and depletes parenchymal tissues of cystine. Based largely upon data produced through this protocol, the Food and Drug Administration approved cysteamine bitartrate for use in cystinosis patients on August 15, 1994. Cysteamine is available as CystagonR through Mylan Pharmaceuticals in 50 mg and 150 mg capsules and as ProcysbiR in 75 mg capsules. By virtue of the current protocol, patients are admitted to the NIH Clinical Center for investigations every two years, except for cases of great interest or urgency. On each 1-3 day admission, a battery of tests is performed and the adequacy of cystine depletion by cysteamine is monitored. This protocol demonstrates the course of cystinosis patients treated with cysteamine, describes new complications of the disorder in poorly treated adults, and maintains NHGRI expertise in the field. Its monitoring and followup of patients over the course of 3 decades represents an invaluable contribution to our understanding of the natural history of this rare disease.

Conditions