Can antiemetics really relieve pain?

The analgesic properties of 2 antiemetic agents--metoclopramide and ondansetron--were investigated in studies which showed that metoclopramide may decrease postoperative opioid requirements, but the analgesic effect of ondansetron is controversial. The postoperative effects of metoclopramide and ondansetron on pain in patients undergoing laminectomy were evaluated. Forty six patients were randomized into 3 groups: group M, which consisted of 15 patients who received intravenous (IV) metoclopramide 0.5 mg 30 minutes before surgery; group O, which consisted of 16 patients who received ondansetron IV 0.1 mg 30 minutes before surgery; and group C, which consisted of 15 patients who received the same volume of saline IV 30 minutes before surgery. The efficacy and duration of analgesia were assessed using a visual analogue scale (VAS) at 0, 0.5, 1, 3, 6, and 24 hours after surgery. Hemodynamic parameters, additional analgesic requirements, and adverse effects were recorded for the study groups. Diclofenac 75 mg was administered intramuscularly as a rescue analgesic during the postoperative period. VAS scores were lower in the metoclopramide group than in the ondansetron and control groups (P<.05, each). The patients in the ondansetron and control groups required much more diclofenac than the patients in the metoclopramide group (P<.05). Metoclopramide administered preoperatively provided postoperative analgesia in patients undergoing elective laminectomy.