The purpose of the study was to evaluate the efficacy and safety of dolasetron for symptomatic relief of pain associated with fibromyalgia (FM).

This prospective, double-blind, placebo-controlled trial randomly assigned 60 patients with FM to receive placebo (n=31) or dolasetron (n=29) 12.5mg/d via the intravenous route on 4days at baseline (M0), 1month (M1), 2months (M2) and 3months (M3) with follow-up to month 12. The primary outcome variable was the reduction in pain intensity measured by visual analogue scale (VAS) between M0 and M3. The secondary outcome variables were patient global impression of change (PGIC), the FM impact questionnaire, assessment of quality of life (SF-36), the hospital anxiety and depression scale, the manual tender point count, and functional symptoms associated with FM.

Reduction in pain intensity at M3 was significantly greater in dolasetron-treated patients (p=0.04, −21.3 on a 0–100 scale) compared with placebo controls (−5.9). More patients in the dolasetron group had ≥30% and ≥50% improvement in pain (42.5% and 28% respectively in the dolasetron group versus 25% and 16% in the placebo group). The PGIC was significantly greater in the dolasetron group at M3 (p=0.02). The other secondary outcomes failed to reach statistical significance. The most common adverse events were constipation, nausea, dizziness and headache, with no significant differences between the two groups.

Intermittent IV dolasetron was safe and efficacious for the reduction of pain intensity associated with FM at 3months.