Effects of Switching from Duloxetine to Milnacipran: Results from a Randomized, Double-Blind, Placebo-Controlled Study in Fibromyalgia (P07.271)

Objective: To evaluate the safety, tolerability, and efficacy of milnacipran following a direct switch from duloxetine in fibromyalgia (FM) patients with inadequate response to duloxetine. Background Milnacipran and duloxetine are approved for the management of FM. As individual patient responses to analgesic medications differ, switching therapies to achieve greater benefit or avoid certain side effects is common. Design/Methods: Patients receiving duloxetine 60 mg/day for ≥4 weeks at screening were eligible. After 2 weeks of open-label duloxetine 60 mg/day, patients with VAS pain scores ≥40 (range, 0-100 mm) and dissatisfied with duloxetine were randomized 4:1 to milnacipran 100 mg/day (n=86) or placebo (n=21) for 10 weeks. The primary efficacy parameter was responder status based on Patient Global Impression of Change (PGIC), with responders defined as patients rating themselves “much improved” or “very much improved”. The secondary efficacy parameter was change from baseline in 1-week recall VAS pain score. Statistical analyses were descriptive and used LOCF to impute missing data. Results: In patients switched from duloxetine to milnacipran, 32.9% were PGIC responders and the mean decrease from baseline in VAS pain was 12.3 mm at the Week 10 visit (23.8% of placebo-treated patients were PGIC responders and the mean decrease in VAS pain was 1.3 mm). In a post hoc analysis, 34.2%, 29.1%, and 25.3% of patients switched to milnacipran had ≥30%, ≥40%, and ≥50% improvement in VAS pain scores, respectively. The most common (TEAEs) in patients switched to milnacipran were nausea (21%) and dizziness (15%); nausea and dizziness occurred in 29% and 5% of patients switched to placebo, respectively. Conclusions: These results suggest that FM patients with an inadequate response to duloxetine treatment may benefit from a switch to milnacipran for management of their symptoms. Additionally, a direct switch from duloxetine to milnacipran was safe and well tolerated in this study. Supported by: Forest Laboratories, Inc. Disclosure: Dr. Bateman has received personal compensation for activities with Forest Laboratories consultations and The Speakers Bureau as a consultant and/or speaker. Dr. Spera has received personal compensation for activities with Forest Research Institute as an employee. Dr. Palmer has received personal compensation for activities with Forest Laboratories, Inc. as an employee. Dr. Trugman has received personal compensation for activities with Forest Laboratories as an employee. Dr. Thacker has received personal compensation for activities with Forest Laboratories, Inc. as and employee. Dr. Lin has received personal compensation for activities with Forest Research Institute as an employee.