A randomized, double-blind, placebo-controlled trial of moclobemide in patients with chronic fatigue syndrome

Background: Chronic fatigue syndrome is characterized by prolonged and disabling fatigue and a range of neuropsychiatric symptoms including depressed and/or irritable mood. To date, no medical or psychotropic therapies have provided clear symptomatic benefit. Method: Ninety patients with chronic fatigue syndrome, diagnosed with our system that approximates CDC criteria, participated in a randomized, placebo-controlled, double-blind trial of 450 to 600 mg/day of moclobemide, a novel reversible inhibitor of monoamine oxidase-A. Results: Fifty-one percent (24/47) of patients receiving moclobemide improved compared with 33% (14/43) of patients receiving placebo (odds ratio = 2.16, 95% confidence interval [CI] = 0.9 to 5.1). Drug response was best characterized symptomatically by an increase in the subjective sense of vigor and energy rather than a reduction in depressed mood. The effect of moclobemide on subjective energy was detectable within the first 2 weeks of treatment and increased across the course of the study. The greatest reduction in clinician-rated disability was in patients with concurrent immunologic dysfunction (mean difference in standardized units of improvement = 0.8, 95% CI = 0.03 to 1.6). Conclusion: Moclobemide produces some improvement in key symptoms experienced by patients with chronic fatigue syndrome. This effect is not dependent on the presence of concurrent psychological distress and is likely to be shared with other monoamine oxidase inhibitors.