Intravenous buspirone for the prevention of postoperative nausea and vomiting

Buspirone, a partial 5HT(1A) agonist and D-2 and D-3 antagonist, has shown promising antiemetic efficacy when given parenterally in animal models, but its efficacy for the prevention of postoperative nausea and vomiting (PONV) is unknown. To study the efficacy and dose-responsiveness of intravenous buspirone for the prevention of PONV. A randomised, double-blind, placebo-controlled study was performed in adults at moderate to high PONV risk undergoing surgery with a general anaesthetic. Patients were randomised to receive an intravenous dose of buspirone (0.3, 1.0, 2.0, 3.0 mg) or placebo at the end of surgery. The primary endpoint was the cumulative 24-h PONV incidence (i.e. any nausea and/or vomiting). Vomiting included retching. Nausea was defined as a score of a parts per thousand yen4 on an 11-point verbal rating scale running from zero (no nausea) to ten (the worst nausea imaginable). A total of 257 patients received the study drug and fulfilled the criteria for inclusion in the primary efficacy and safety analyses. With placebo, the mean 24-h PONV incidence was 49.0 % (90 % confidence interval [CI] 37.5-60.5 %). With buspirone, that incidence ranged from a mean of 40.8 % (29.3-52.4 %) in the 1 mg arm to 58.0 % (46.5-69.5 %) in the 0.3 mg arm (P > 0.05 for all comparisons). There was no difference between placebo and buspirone at any dose for any other efficacy endpoint, nor in the number or severity of adverse events or any other safety measures. We were unable to show that intravenous single-dose buspirone, at the tested dose-range, was effective at preventing PONV in surgical adult patients. The present study emphasises the difficulty in extrapolating from animal models of emesis to clinical efficacy in PONV.