Objectives: Evaluate the efficacy and safety of duloxetine at doses up to 120 mg once daily in patients with fibromyalgia.
Methods: This was a phase 3, 60-week study, which included an 8-week open-label period followed by a 52-week, randomized, double-blind period. Patients received duloxetine 30 mg daily for 1 week and duloxetine 60 mg daily for 7 weeks and were then randomized to receive either 60 or 120 mg daily (1:2 ratio).
Results: Enrolled patients (N=350, 95.7% female) exhibited moderate disease symptoms at study entry (Brief Pain Inventory average pain=6.7, Clinical Global Impression of Severity=4.1, and Patient's Global Impression of Severity=4.1). Significant pain reduction in patients was observed during the open-label study phase. This pain reduction continued during the 52-week double-blind study phase, as demonstrated by additional mean decreases in the Brief Pain Inventory average pain score within both duloxetine groups. The most common (> or =15%) treatment-emergent adverse events (overall phase) were nausea, headache, insomnia, dizziness, constipation, and dry mouth. Seventy-four (21.1%) patients reported adverse events as a reason for discontinuation [most common (>1%) were insomnia, vomiting, diarrhea, dizziness, and nausea]. The mean change (SD) in sitting systolic blood pressure (mm Hg) was -0.1 (14.4), in sitting diastolic blood pressure was -0.2 (9.6), in sitting pulse rate was 1.9 (10.4) bpm, and in weight was 0.7 (4.3) kg.
Discussion: The profile of duloxetine for the long-term treatment of fibromyalgia was consistent with that seen in other indications for which the drug is currently marketed.