Effect of milnacipran on body weight in patients with fibromyalgia

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/m(2)). 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).