Background & Objectives: Postoperative nausea and vomiting (PONV) is one of the most common complications of anesthesia and without prophylactic intervention occurs in about one-third of patients under general anesthesia. The aim of this study was to compare the efficacy of ondansetron and metoclopramide in reducing PONV after laparoscopic cholecystectomy.

  Methods : In this study, 90 patients undergoing laparoscopic cholecystectomy were randomly allocated into three equal groups (n=30) and in the first group 10 mg metoclopramide, in the second group 4 mg ondansetron and for placebo group 2 cc normal saline preoperatively were injected. Anesthesia complications in recovery and nausea and vomiting in recovery and 6 hours and 24 hours after surgery were evaluated. Data were analyzed by SPSS software with chi-square test and analysis of variance (ANOVA). P<0.05 was considered significant.

  Results: The incidence of nausea in placebo group was 66.7 %, in metoclopramide group was 43.3 % and in ondansetron group was 33.3 %. The difference only between placebo and ondansetron groups was significant (p=0.019). The incidence of vomiting in placebo group was 56.7%, in metoclopramide group was 20% and in ondansetron group was 26.7% and there was significant difference between placebo and ondansetron groups (p=0.035) and between placebo and metoclopramide groups (p=0.007), whereas there was not any significant difference between intervention groups (p=0.12). Also anti-emetic drug administration in ondansetron group (40%) in comparison with metoclopramide (63.3%) and placebo (66.7%) was lower, but this difference was not statistically significant (p= 0.07).

  Conclusion: For prevention of vomiting after laparoscopic cholecystectomy, both metoclopramide and ondansetron are effective. In comparing these two drugs, in preventing of nausea ondansetron is more effective than metoclopramide, whereas there was not any significant difference between two drugs in preventing of vomiting.