An open-label long-term phase III extension trial to evaluate the safety and efficacy of pregabalin in Japanese patients with fibromyalgia

Objectives To assess the long-term safety and efficacy of pregabalin for the treatment of Japanese patients with fibromyalgia (FM). Methods This 53-week, open-label extension study was conducted at 20 study sites in Japan in patients with FM who had completed a preceding 16-week, placebo-controlled, double-blind trial. Patients received pregabalin, starting at 150 mg/day and increasing to a maintenance dose of 300 or 450 mg/day. The primary endpoint was safety, and secondary endpoints included measures of pain, sleep, and physical functioning. Results 106 patients entered the trial and received at least one dose of the study drug. The most common treatment-related adverse events were somnolence, dizziness, increased weight, and constipation. There were no treatment-related serious or severe adverse events. There were five (4.7 %) discontinuations due to adverse events, of which three (2.8 %) were considered related to the study drug. Most adverse events resolved over time and could be managed without dose reduction or treatment discontinuation. Improvements in secondary efficacy endpoints of pain, sleep, and physical functioning emerged early in the study and were maintained for the duration of treatment. Conclusions These data indicate that the long-term treatment of Japanese FM patients with pregabalin may be both safe and effective.