Efficacy and tolerability of intravenous tropisetron in the treatment of fibromyalgia

Objective: To determine the efficacy of a serotonin receptor (5-HT3) antagonist in the treatment of fibromyalgia (FM) in a prospective, randomized, double-blind, placebo-controlled, multicentre trial. Methods: Twenty-one female patients ( age 21 - 63 years) with FM according to the American College of Rheumatology classification criteria for FM were assigned randomly to either a placebo group or to receive a daily intravenous bolus injection of 5 mg tropisetron for 5 days. Results: In patients receiving tropisetron, the visual analogue scale ( VAS) score for pain decreased by 28.9 compared with a decrease of 6.8 in the placebo group [ probability ( p) = 0.063; effect size: 0.794]. Similar results were obtained using a body diagram pain score as a secondary efficacy parameter: mean pain reduction was 27.2 in the tropisetron group, versus 2.8 in the placebo group (p = 0.038; effect size: 0.902). Conclusion: 5-HT3 receptor antagonists provide significant pain relief for a group of FM patients.