Optimal anti-emetic dose of granisetron for preventing postoperative nausea and vomiting.

In order to determine the optimal effective dose of granisetron for preventing postoperative nausea and vomiting, the drug was administered in doses of either 20, 40 or 60 micrograms.kg-1. The efficacy of granisetron was evaluated in a randomized, double-blind comparison with placebo in 100 patients undergoing general anaesthesia for major gynaecological surgery. The patients received a single dose of either granisetron or placebo (saline) iv immediately after recovery from anaesthesia. The effects were assessed during the 24 hr after recovery from anaesthesia by means of a nausea and vomiting score; 0 = no emetic symptoms, 1 = nausea, 2 = vomiting. The treatment groups were similar for patient characteristics, surgical procedures and anaesthetics administered. The mean scores were 0.7, 0.6, 0.2 and 0.2 after administration of placebo, granisetron 20, 40 and 60 micrograms.kg-1, respectively. Granisetron 40 micrograms.kg-1 was as effective as 60 micrograms.kg-1 and both resulted in reduction of the scores compared with placebo and granisetron 20 micrograms.kg-1 (P < 0.05). In conclusion, granisetron 40 micrograms.kg-1 is considered to be the appropriate dosage for preventing postoperative emesis after anaesthesia.