Randomized, Double-Blind, Controlled Trial of Acetylcysteine in Amyotrophic Lateral Sclerosis

Background: Free radicals may play a role in the pathogenesis of amyotrophic lateral sclerosis. Objective: To investigate the efficacy of the free radical scavenging agent acetylcysteine in patients with amyotrophic lateral sclerosis. Design: Randomized, double-blind, placebo-controlled clinical trial to assess the effect of treatment with acetylcysteine on survival and disease progression. Setting: A university hospital referral setting. Patients: One hundred ten consecutive patients who fulfilled the diagnostic criteria for amyotrophic lateral sclerosis, followed up at monthly intervals for 12 months. Intervention: Acetylcysteine or placebo in a dose of 50 mg/kg per day subcutaneously for 12 months. Main Outcome Measure: Survival. Results: After 12 months, 35 patients (65%) treated with acetylcysteine and 30 (54%) given placebo were still alive (hazard ratio, 0.74 in the acetylcysteine group relative to the placebo group; 95% confidence interval, 0.41 to 1.33; log-rank test, P =.31). Rates of disease progression, as expressed by decline in muscle strength, pulmonary function, disability, and bulbar function were similar in both groups. In the subgroup of 81 patients with limb onset of the disease, 28 patients (74%) in the acetylcysteine group and 22 (51%) in the placebo group survived 12 months (hazard ratio, 0.50; 95% confidence interval, 0.24 to 1.04; P =.06). In the bulbar subgroup of 29 patients, seven patients (44%) receiving acetylcysteine and eight (62%) receiving placebo were alive at the end of the study (hazard ratio, 1.66; 95% confidence interval, 0.56 to 4.99; P =.36). Conclusion: In this trial, treatment with the free radical scavenger acetylcysteine did not result in a major increase in 12-month survival or a reduction in disease progression in patients with amyotrophic lateral sclerosis.