Drugs Exp Clin Res. 2003;29(2):91-4. Stratz T, Kees F, Muller W. Hochrhein-Institut fur Rehabilitationsforschung, Bergseestrasse 61, D-79713 Bad Sackingen, Germany.
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.
PMID: 12951840 [PubMed – in process]