Ipecacuanha-induced emesis: a human model for testing antiemetic drug activity.

In a double-blind, randomized, parallel-group study, five groups of 10 healthy men received single 5-minute infusions of 8 mg, 4 mg, 1 mg, 0.25 mg, or 0.1 mg ondansetron (as hydrochloride dihydrate) 30 minutes before oral administration of 30 ml syrup of ipecacuanha. Emetic episodes and nausea (100 mm visual analog scale) were assessed over an 8-hour period. There were no emetic episodes after 8 or 4 mg ondansetron. Seven, nine, and 10 subjects vomited after 1 mg, 0.25 mg and 0.1 mg ondansetron, respectively, with median times to onset of 62, 31, and 37 minutes. Median peak nausea scores were 0 mm for both 8 and 4 mg ondansetron and 30, 53, and 26 mm for 1, 0.25, and 0.1 mg ondansetron. Adverse events were mild. This model showed a close correlation with clinically effective doses of ondansetron. It may be successfully and safely used to assess the antiemetic potential of 5-HT3-receptor antagonists in healthy subjects.