Dutasteride to Treat Spinal and Bulbar Muscular Atrophy (SBMA)

Study Summary

This study will determine if the drug dutasteride can improve weakness, mobility, functioning, nerve function, and quality of life in patients with spinal and bulbar muscular atrophy (SBMA). Patients with this inherited disease have an abnormal androgen receptor protein. The male hormones testosterone and dihydrotestosterone (DHT) bind to this abnormal receptor, causing damage to nerve cells that innervate muscle and leading to weakness. Dutasteride decreases DHT production. Lowering DHT levels may decrease the harmful effects of DHT to the nerves and improve strength in people with SBMA. Males 18 years of age and older with SBMA who have neurological symptoms and can walk 100 feet (with or without assistive devices) may be eligible for this study. Candidates are screened with a blood test and a review of their medical records and genetic studies. Participants undergo the following procedures: * Blood and urine tests, history and physical examination, assessment of muscle strength * Quality-of-life questionnaire * Tests to assess functional abilities, such walking up steps, keeping the head up while lying down, and other measures * Nerve conduction study and motor unit number estimation to assess nerve damage. A probe placed on the skin delivers small electrical impulses and wires taped to the skin record the impulses. * Quantitative muscle testing to measure strength. The subject pushes and pulls levers attached to a gauge. Strength is recorded by a computer. * Medication. Participants are divided into two groups. One group is given the study drug, dutasteride; the other receives a placebo (sugar pill). All participants take their assigned medication once a day for 24 months. * Follow-up evaluations. Every 6 months for 2 years, participants return to NIH to repeat the tests described above to determine the effects of the dutasteride. Nerve and quantitative muscle testing is not done at the 6- and 18-month visits. * In addition to their follow-up appointments her

Primary Outcome

Quantitative muscle assessment (QMA) was done with a fixed frame dynamometer, a strain gauge tensiometer, and a computer-aided acquisition system. Maximal voluntary isometric muscle contractions were measured twice, the average was calculated, and the results were summed over 22 muscle groups (11 on each side). The total force was scaled for body weight and expressed as percent change from baseline. Measurements were performed at 0, 12, and 24 months. The calculated percent changes at 12 and 24

Interventions

• DRUG Placebo
• DRUG Dutasteride