Efficacy and tolerability of tropisetron in primary fibromyalgia--a highly selective and competitive 5-HT3 receptor antagonist. German Fibromyalgia Study Group.
OBJECTIVE
Based on a potential role for serotonin receptors in fibromyalgia, we investigated the efficacy and tolerability of treatment with tropisetron, a highly selective, competitive inhibitor of the 5-HT3 receptor.


METHODS
In this prospective, multicenter, double-blind, parallel-group, dose-finding study, 418 patients suffering from primary fibromyalgia (ACR criteria) were randomly assigned to receive either placebo, 5 mg, 10 mg or 15 mg tropisetron once daily, respectively. The duration of treatment was 10 days. The clinical response was measured by changes in pain-score, visual analog scale (VAS), and the number of painful tender-points.


RESULTS
Treatment with 5 mg tropisetron resulted in a significantly higher response rate (39.2%) when compared with placebo (26.2%) (p=0.033). The absolute reduction in pain-score was -13.5% for 5 mg tropisetron, -13.0% for 10 mg tropisetron, and -6.3% for placebo (p<0.05). The effects of 15 mg tropisetron were similar to placebo, thus suggesting a bell-shaped dose-response curve. Compared with placebo, treatment with 5 mg tropisetron led to a significant improvement (p<0.05) in VAS, while a clear trend in terms of clinical benefit was seen with 10 mg tropisetron. The number of painful tender-points was also reduced significantly (p=0.002) in the 5 mg tropisetron group. Of interest, during the 12-month follow-up period, pain intensity of responders on 5 mg and 10 mg tropisetron was still markedly below baseline. The treatment was well tolerated, with gastro-intestinal complaints being the most frequently reported side effects, in keeping with the known safety profile for 5-HT3 receptor antagonists.


CONCLUSIONS
This study demonstrates the efficacy of short-term treatment with 5 mg tropisetron once daily in primary fibromyalgia. Treatment was well tolerated and prolonged clinical benefits were seen.
Färber
L
L
Institut für Pharmakologie der Universität Regensburg, Germany. lothar.faerber@pharma.novartis.com
Stratz
T
T
Brückle
W
W
Späth
M
M
Pongratz
D
D
Lautenschläger
J
J
Kötter
I
I
Zöller
B
B
Peter
H H
HH
Neeck
G
G
Alten
R
R
Müller
W
W
D000293:Adolescent; D000328:Adult; D000368:Aged; D004311:Double-Blind Method; D005260:Female; D005356:Fibromyalgia / Q000188:drug therapy* / Q000503:physiopathology; D005500:Follow-Up Studies; D006801:Humans; D007211:Indoles / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010919:Placebos; D011446:Prospective Studies; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D044406:Receptors, Serotonin, 5-HT3; D012702:Serotonin Antagonists / Q000009:adverse effects / Q000627:therapeutic use*; D000077526:Tropisetron
D007211:Indoles; D010919:Placebos; D011985:Receptors, Serotonin; D044406:Receptors, Serotonin, 5-HT3; D012702:Serotonin Antagonists; D000077526:Tropisetron