A pilot randomised controlled trial of chlorpromazine to prevent postoperative nausea and vomiting

Abstract

PURPOSE: Safety and efficacy of a small dose of chlorpromazine to prevent postoperative nausea and vomiting (PONV) was studied to enable design of a larger trial. Since phenothiazines may prolong the electrocardiogram QT interval and cause dangerous arrhythmias, we focussed on this side effect. METHODS: A double-blind randomised controlled trial was conducted in a tertiary care teaching hospital comparing chlorpromazine 10mg IV at anesthetic induction to saline with primary outcome prevention of PONV (defined as nausea and/or vomiting and/or retching at any time) in laparoscopic surgery, and secondary outcomes cardiac and other side effects. With University Research Ethics Board approval, 120 subjects were recruited. PONV was assessed in the Post-anesthetic Care Unit and 24 hours later.RESULTS: Group demographics were not different. For incidence of PONV, the chlorpromazine group (incidence; ratio; [95%Confidence Interval]: 33/60; 0.55 [0.42 to 0.68]) was not significantly different from placebo (40/60; 0.67 [0.55 to 0.79]. There was no difference in corrected QT or Tp-e intervals. One subject in each group was sleepier than expected; one in the CPZ group had lower blood pressure than expected after anesthesia induction, which was easily corrected.CONCLUSION: Although not statistically significant, PONV occurred more often in the placebo group than the treated group. A larger dose may be efficacious. Chlorpromazine is inexpensive and, at this dose, appears to be safe in the context of anesthesia practice. This study permitted sample size estimation (n = 100/arm) for a definitive study. This study was funded by a grant from The Royal University Hospital Foundation. No author has any commercial or other affiliation that might constitute a conflict of interest.