Do cytochrome enzymes influence the therapeutic effect of tropisetron in fibromyalgia?
It is well known that the 5-HT3 receptor tropisetron shows a bell-shaped dose-response curve in the treatment of pain associated with fibromyalgia. The best results are achieved with a daily oral dose of 5 mg for 10 days. Dosages of 10 and 15 mg per day have a much weaker effect. If tropisetron is administered by intravenous injection, a regimen of 5 mg per day over 5 days will suffice to reduce pain substantially. An open study of selected cases revealed that 2 mg of tropisetron daily for 5 days also yielded satisfactory pain reduction, whereas this was not observed in a placebo-controlled double-blind study. We therefore investigated which factors might be responsible for the different effects of the drug. Judging from the above-mentioned studies, the effect of a minimum dosage of tropisetron could be assumed to be partly attributable to the different half-life periods. This is supported by the markedly different rates of constipation, a characteristic side effect of the drug, reported by the two studies.
Stratz
T
T
Hochrhein-Institut für Rehabilitationsforschung, Bergseestrasse 61, D-79713 Bad Säckingen, Germany.
Kees
F
F
Müller
W
W
D000328:Adult; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D005260:Female; D005356:Fibromyalgia / Q000188:drug therapy*; D006207:Half-Life; D006801:Humans; D007211:Indoles / Q000097:blood / Q000378:metabolism* / Q000627:therapeutic use; D007275:Injections, Intravenous; D008875:Middle Aged; D010865:Pilot Projects; D012702:Serotonin Antagonists / Q000097:blood / Q000378:metabolism* / Q000627:therapeutic use; D016896:Treatment Outcome; D000077526:Tropisetron
D007211:Indoles; D012702:Serotonin Antagonists; D000077526:Tropisetron; D003577:Cytochrome P-450 Enzyme System