Ondansetron and dexamethasone dose combinations for prophylaxis against postoperative nausea and vomiting

Patients at high risk of postoperative nausea and vomiting often receive more than one prophylactic antiemetic drug. In this study we sought to determine whether one or more of four dose combinations of dexamethasone and ondansetron was superior in efficacy.

In a randomized, double-blind trial of four dose combinations, women having day-surgical gynecologic laparoscopy received IV dexamethasone and ondansetron 4 + 4 mg (Group D4/O4, n = 154), 4 + 2 mg (Group D4/O2, n = 151), 2 + 4 mg (Group D2/O4, n = 154), or 2 + 2 mg (Group D2/O2, n = 155).

The groups were not significantly different for predicted risk or characteristics. The incidence of vomiting until discharge did not differ significantly (5%, 4%, 9% and 8% for Groups D4/O4, D4/O2, D2/O4 and D2/O2 respectively, P = 0.17), nor were there significant differences among groups in the incidence of vomiting until 24 h postoperatively, no nausea and no vomiting, antiemetic treatment, neither vomiting nor antiemetic treatment (80%-83% across groups), or inpatient satisfaction and recovery scores, or time to discharge. Average nausea scores were low in all groups, but the incidence of nausea until 24 h postoperatively was significantly higher among groups receiving only 2 mg of dexamethasone (P < 0.03).

All combinations were associated with a low incidence of vomiting and rescue treatment, with dexamethasone 2 mg plus ondansetron 2 mg not significantly different to other dose combinations except that groups receiving 2 mg dexamethasone had a more frequent incidence of nausea.