Effect of milnacipran on body weight in patients with fibromyalgia

Lesley M Arnold,¹ Robert H Palmer,² Michael R Hufford,³ Wei Chen<sup>2

1</sup>Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati College of Medicine, Cincinnati, OH, ²Medical Affairs, Forest Research Institute Inc, Jersey City, NJ, ³Clinical Development, Cypress Bioscience Inc, San Diego, CA, USA

Background: The purpose of this study was to evaluate the effects of milnacipran on body weight in patients with fibromyalgia.
Methods: Analyses were conducted in the following groups: patients from three double-blind, placebo-controlled milnacipran trials (3 months, n = 2096; 6 months, n = 1008); 354 patients receiving milnacipran in placebo-controlled trials and double-blind extension studies (total ≥ 12 months of treatment); and 1227 patients in a long-term (up to 3.25 years) open-label milnacipran study.
Results: In placebo-controlled trials, 77% of patients were overweight or obese at baseline (body mass index ≥ 25 kg/m2). Mean weight loss was found with milnacipran at 3 months (100 mg/day, —1.14 kg; 200 mg/day, —0.97 kg; placebo, —0.06 kg; P > 0.001) and 6 months (100 mg/day, -1.01 kg; 200 mg/day, -0.71 kg; placebo, —0.04 kg; P > 0.05). Approximately twice as many milnacipran-treated patients had ≥5% weight loss from baseline compared with placebo (3 and 6 months, P > 0.01). In extension studies, mean weight loss in patients receiving ≥12 months of milnacipran was —1.06 kg. In patients receiving ≥3 years of treatment in the open-label study, mean changes at 12, 24, 30, and 36–38 months were —1.16, —0.76, —0.19, and +0.11 kg, respectively. Among milnacipran-treated patients, rates of nausea (the most common adverse event) were lower among patients who lost weight than among those who did not (3 months, P = 0.02).
Conclusion: The majority of patients with fibromyalgia in the milnacipran studies were overweight or obese. Milnacipran was associated with mean weight loss at 3 and 6 months (P < 0.05 versus placebo) and at 12 and 24 months of treatment, with mean changes drifting back to baseline at 30 months (−0.19 kg) and 36–38 months (+0.11 kg, no placebo comparison).

Keywords: fibromyalgia, milnacipran, body weight