A study to evaluate the effect of ondansetron on psychomotor performance after repeated oral dosing in healthy subjects.

The aim of the study was to determine the effect of repeated oral administration of ondansetron, a 5-hydroxytryptamine type 3 (5-HT3) receptor antagonist, on psychomotor performance. The study was of a randomised, double-blind, four-way, cross-over design in 12 healthy subjects, with 1 mg and 8 mg ondansetron, placebo and 2 mg lorazepam evaluated. Each subject received five administrations per treatment period. Ondansetron, 1 mg and 8 mg, and placebo were given as twice daily dosing for 2 1/2 days. Lorazepam was administered as a 2 mg single oral dose which was taken as the fifth administration; placebo was given for the remaining four doses. Within each treatment period, subjects underwent a baseline (pre-dose) assessment of psychomotor performance using four commonly used and validated psychomotor tests, and were then re-assessed after the fifth and final dose over a 7-h, post-dose period. Following dosing with lorazepam, statistically significant changes were seen in five of the six test variables compared with placebo. Ondansetron, at both the 1 mg and the 8 mg doses, did not produce a statistically significant effect on any measure of psychomotor performance compared with placebo.