Presented at the 2012 AAPM Annual Meeting « Back

Continuing Efficacy of Milnacipran Demonstrated After Long-Term Treatment of Fibromyalgia

Daniel J. Clauw, MD, dclauw@med.umich.edu¹, Philip Mease, MD², Yimin Ma, PhD³ , Arlene Baldecchi, BS MT (ASCP) CCRA³ , Robert .H Palmer, MD³, Joel M. Trugman, MD³, (1) University of Michigan, Ann Arbor, Michigan, (2) Seattle Rheumatology Associates and Swedish Medical Center, Seattle, Washington, (3) Forest Research Institute, Jersey City, New Jersey

Introduction: Fibromyalgia patients enrolled in a long-term, open-label study of milnacipran (up to 3.25 years) were eligible to participate in this multicenter, double-blind (DB), placebo-controlled discontinuation study. This study evaluated the effect of discontinuing long-term milnacipran treatment on the symptoms of fibromyalgia. Methods: After 4 weeks of open-label milnacipran treatment (50–200 mg/day), patients taking milnacipran ≥100 mg/day and achieving a ≥50% reduction in visual analog scale (VAS) pain from pre-milnacipran exposure were randomized 2:1 to milnacipran (milnacipran continued) or placebo (milnacipran withdrawn) for 12 weeks. The primary efficacy parameter was the time to loss of therapeutic response (LTR), defined as an increase in VAS pain score to <30% reduction from pre-milnacipran exposure or a worsening of fibromyalgia requiring an alternative treatment. Time to LTR was analyzed using Kaplan-Meier estimates and the log-rank test. The study protocol was approved at each site by an IRB; all patients provided written, informed consent. Results: Time to LTR was significantly shorter for patients withdrawn from milnacipran (n = 50) compared with patients continuing milnacipran (n = 100, P = .0004). Median time to LTR was 56 days for patients withdrawn from milnacipran and not calculable for patients continuing milnacipran (over half had not lost therapeutic response by study end). At the end of DB treatment, 64% of patients in whom milnacipran was withdrawn met LTR criteria versus 35% of patients continuing milnacipran. Conclusions: The loss of therapeutic response upon discontinuation of long-term milnacipran treatment provides evidence of the continuing efficacy of milnacipran as a treatment for fibromyalgia.

Funding: This study was supported by Forest Research Institute, a subsidiary of Forest Laboratories, Inc. and Cypress Bioscience, Inc.