To assess the long-term safety, tolerability, and efficacy of duloxetine in patients with fibromyalgia.
We report results from the 6-month extension phases of 2 randomized, double-blind, placebo-controlled clinical trials having 6-month placebo-controlled phases. In Study 1, all patients received duloxetine 120 mg/d after 28 weeks on placebo or duloxetine 60 or 120 mg/d. In Study 2, patients taking placebo were titrated to duloxetine 60 mg/d after 27 weeks on treatment, while duloxetine-treated patients remained on their dosages of 60 or 120 mg/d. Safety and tolerability were assessed via discontinuation rates, treatment-emergent adverse events (TEAEs), and changes in vital signs and laboratory measures. The primary efficacy measure was the Brief Pain Inventory average pain severity score.
The percentage of patients entering and completing the extension phase was 56% (156/278) for Study 1 and 69% (140/204) for Study 2. Groups titrating from placebo to duloxetine showed the highest discontinuation rates due to an adverse event (Study 1, 25%; Study 2, 19%) and TEAE rates (Study 1, 82%; Study 2, 77%). The most common TEAEs were nausea and dry mouth. No significant within-group changes in blood pressure occurred in any group. Significant within-group mean increases in pulse (bpm) were observed in the placebo/duloxetine 120 mg group in Study 1 (3.7 [SD = 11.2], P <or= 0.01) and the placebo/duloxetine 60 mg group in Study 2 (4.8 [SD = 10.2], P <or= 0.001). Most treatment groups showed small mean change improvements in the Brief Pain Inventory average pain severity score.
These findings support a positive risk/benefit profile for duloxetine in the long-term treatment of fibromyalgia.