Fibromyalgia treatment with intravenous tropisetron administration.

A prospective, randomized, placebo-controlled, multicenter, double-blind trial in fibromyalgia patients demonstrated that peroral daily treatment with 5 mg tropisetron for 10 days produced a significant reduction in pain and other symptoms. The aim of the present study was to determine whether intravenous administration of 2 mg tropisetron daily for a limited period of time would produce quicker and more favorable results. In the first cohort 18 fibromyalgia patients received a single intravenous injection of 2 mg tropisetron. In the second cohort 24 fibromyalgia patients were treated with 2 mg intravenous tropisetron daily for 5 days. Pain intensity was measured with the visual analog scale and the pain score. Pain at tender and control points (dolorimeter) as well as 17 ancillary symptoms before and after treatment were evaluated. Pain intensity was followed-up by means of a patient diary until recurrence. Dolorimetry revealed that a single intravenous injection of 2 mg tropisetron significantly reduced pain and enhanced pain threshold. These effects, however, lasted for only a few days. Of 18 patients in the first cohort, only three showed no response to therapy. Of the 24 patients in the second cohort, 23 showed pain reduction when 2 mg tropisetron was administered daily for 5 days. Pain relief lasted for 2 weeks to 2 months in 20 of these patients. Two patients stopped filling in the pain diary. Twelve ancillary symptoms such as sleep disturbances, fatigue, morning stiffness were also significantly improved by the latter treatment. In the global assessment 16 out of 24 patients showed significant improvement and seven showed slight improvement. Only one patient experienced no improvement. Tolerability was good. In conclusion, intravenous injection of 2 mg of the 5-hydroxytryptamine3 receptor antagonist tropisetron once daily for 5 days produced a longer-lasting therapeutic effect on fibromyalgia symptoms than did peroral daily treatment with 5 mg of this drug. The results achieved are currently being evaluated in a randomized, placebo-controlled, double-blind trial.