AUSTIN, TX—Sustained long-term efficacy and tolerability of milnacipran—in some cases, exceeding three years of continuous usage—is supported in the treatment of patients with fibromyalgia, according to results of an open-label study presented during the American Pain Society’s 30th Annual Scientific Meeting.

Fibromyalgia is a chronic disorder characterized by widespread pain and other symptoms that adversely impact function and health-related quality of life. For that reason, durable efficacy is an important treatment goal, noted Lesley Arnold, MD, from the University of Cincinnati College of Medicine, Cincinnati, OH, and colleagues.

To determine long-term efficacy of milnacipran, which is approved for the management of fibromyalgia, treatment effects were evaluated in 1,227 patients in a safety and efficacy study over a period that could exceed three years. Eligible patients were those with fibromyalgia who had successfully completed previous studies of milnacipran. The multicenter, open-label, flexible-dose study comprised a two-week washout period, a two-week dose-escalation period (to milnacipran 100mg/day), an 8-week stable-dose period (at milnacipran 100mg/day), and a flexible-dose period (milnacipran 50–200mg/day) for the remainder of the study. Key efficacy outcomes included 24-hour visual analog scale (VAS) and weekly recall pain (0–100 scale), Patient Global Impression of Change (PGIC), Patient Global Disease Status (PGDS), SF-36 Physical Component Summary (SF-36 PCS), and the Brief Pain Inventory (BPI).

Of the 1,227 patients, 47.7% were considered completers; 206 patients reached the final visit and 379 were enrolled when the study was terminated. Efficacy results were reported as mean changes from study baseline following the two-week washout period. At the final visit, patients treated with milnacipran demonstrated a mean (SEM) improvement from baseline in 24-hour VAS recall pain scores of 23.1 points (1.82) (observed cases). Improvements in VAS weekly recall pain, BPI scores, global status (PGIC, PGDS), and physical function (SF-36 PCS) were all observed with milnacipran treatment.

Over the three-year study, the most common treatment-emergent adverse events were nausea (25.9%), headache (13.4%), hypertension (11.2%), and sinusitis (10.4); 20.9% of patients discontinued the study due to these events, primarily nausea.