Effects of the antidepressant duloxetine on body weight: Analyses of 10 clinical studies

Objective: To assess the effect of duloxetine, an inhibitor of serotonin and norepinephrine reuptake, on body weight of patients with major depressive disorder (MDD). Method: Body weight data were obtained from all 10 phase II and III registration studies of duloxetine in the treatment of MDD, as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), performed by Eli Lilly and Company between February 1999 and July 2003. Both acute (8-9 weeks) and long-term (26, 34, and 52 weeks) studies were analyzed. Results: In the acute placebo-controlled studies, duloxetine-treated patients had a mean change of -0.5 kg compared with a change of 0.2 kg for placebo-treated patients (p < .001); no consistent relationship between duloxetine dose and weight change was observed. In placebo-controlled studies including an active comparator arm, similar acute mean weight changes were seen in duloxetine-treated and fluoxetine-treated patients (-0.7 kg vs. -0.6 kg) and in duloxetine-treated and paroxetine-treated patients (-0.3 kg vs. -0.2 kg). During longer-term treatment (34 weeks), mean weight change in patients treated with duloxetine 40 mg b.i.d. was not significantly different from that seen in placebo-treated patients (0.7 kg vs. 0.1 kg), while patients treated with the higher duloxetine dose of 60 mg b.i.d. or with paroxetine gained significantly (p ≤ .05) more weight than placebo-treated patients (0.9 kg, 1.0 kg, and 0.1 kg, respectively). In a 52-week open-label study, duloxetine-treated patients had a mean weight gain of 1.1 kg at endpoint (p < .001). Conclusion: Duloxetine-treated patients experienced weight loss after short-term treatment, followed by modest weight gain on longer-term treatment. The size of the weight changes observed suggests that the antidepressant duloxetine has minimal effects on weight for the majority of patients.