THE PHARMACOKINETICS OF ONDANSETRON AFTER INTRAVENOUS-INJECTION IN HEALTHY-VOLUNTEERS PHENOTYPED AS POOR OR EXTENSIVE METABOLIZERS OF DEBRISOQUINE

The pharmacokinetics of the 5-HT3 receptor antagonist ondansetron foll owing an 8 mg i.v. dose were investigated in 12 subjects previously ph enotyped with debrisoquine. Six subjects were poor metabolisers (debri soquine metabolic ratios 29-131) and six were extensive metabolisers ( debrisoquine metabolic ratios 0.45-3.4). There was no significant diff erence in AUC, C(max), CL or t1/2 between the poor and extensive metab olisers. It is concluded that ondansetron clearance is not mediated ex clusively by cytochrome P-450 2D6.