Long-Term Study of Nitisinone to Treat Alkaptonuria

Study Summary

This 3-year study will examine the safety and effectiveness of long-term use of nitisinone (Orfadin) for treating joint problems in patients with alkaptonuria, an inherited disease in which a compound called homogentisic acid accumulates. The excess homogentisic acid causes arthritis and limited joint movement. It can also cause heart valve damage and kidney stones. Patients between 30 and 80 years of age with alkaptonuria may be eligible for this study. Patients must have hip involvement, but at least one remaining hip joint. Candidates are recruited from among patients enrolled in protocol 00-HG-0141, "Clinical, Biochemical, and Molecular Investigations into Alkaptonuria." Participants may enter both protocols simultaneously. Participants are randomly assigned to one of two treatment groups: one group takes their regular medicines plus a 2-mg nitisinone capsule daily; the other group takes only their regular medicines. Patients taking nitisinone have blood tests to measure liver function 2 weeks and 6 weeks after starting treatment. Before starting therapy, all patients are admitted to the NIH Clinical Center for 4-5 days to undergo the following procedures: * Medical history and physical examination * 24-hour urine collection to test for sugar, protein, and other molecules * Blood tests for liver and thyroid function, blood counts, and blood chemistries * Blood and urine tests to measure tyrosine and other amino acids and homogentisic acid * Bone x-rays * Spiral CT (computed tomography) of the abdomen to detect kidney stones * Eye examination and evaluations by specialists in rehabilitation medicine and pain, plus other consults in skin, brain, lung, heart, and kidney, as needed All patients, whether or not they receive nitisinone, return to the Clinical Center for a 2-3 day follow-up admission every 4 months for a history and physical examination, blood tests, and two 24-hour urine collections. Every 12 months (12, 24 and 36 months after starting the study),

Primary Outcome

Change from baseline in the total (external + internal) hip range of motion (ROM) in the worse hip at 36 months. The patient lies on exam table in the supine position. The patient flexes his/her hip and knee to 90 degrees. The examiner measures the patient's hip external rotation and hip internal rotation range of motion with a goniometer.

Interventions

• DRUG Nitisinone (NTBC)