Oral ondansetron, tropisetron or metoclopramide to prevent postoperative nausea and vomiting: a comparison in high-risk patients undergoing thyroid or parathyroid surgery

Background: Oral antiemetic prophylaxis may be a practical alternative to intravenous administration. Entravenous ondansetron and tropisetron prevent postoperative nausea and vomiting (PONV) at least as efficiently as traditional antiemetics, droperidol and metoclopramide. We tested the hypothesis that the incidence of PONV after oral ondansetron or tropisetron prophylaxis is lower compared with metoclopramide among high-risk patients. Methods: In a prospective, double-blind study we studied 179 high-risk patients who received either ondansetron 16 mg, tropisetron 5 mg, or metoclopramide 10 mg orally 1h before the operation. A standard general anesthetic technique and postoperative analgesia were used. The incidence of PONV and the need for rescue antiemetic medication was recorded for 24h. Results: In the postanesthesia care unit, the incidence of PONV was lower after premedication with tropisetron compared with ondansetron and metoclopramide (13%, 32% and 39%, respectively). The incidence of PONV during 0-24h was the same in each group (68%, 58% and 75% in the ondansetron, tropisetron and metoclopramide group, respectively), but the incidence of vomiting was significantly lower after ondansetron (34%) and tropisetron (22%) prophylaxis compared with metoclopramide (53%). The need for additional antiemetics was significantly lower after tropisetron prophylaxis compared with metoclopramide. Patient satisfaction was significantly higher after tropisetron than after metoclopramide. Conclusions: In the initial period, the incidence of PONV was lower after premedication with oral tropisetron than after ondansetron or metoclopramide. Considering the entire 24-h postoperative period, the incidence of PONV was the same after all three premedications, but the incidence of vomiting was lower after oral ondansetron and tropisetron than after metoclopramide.