The Prophylactic Effect of Oral Olanzapine on Postoperative Nausea and Vomiting in Laparoscopic Gynecological Surgery: A Randomized Clinical Trial

Background Although the antiemetic effect of olanzapine on chemotherapy-induced nausea and vomiting has been characterized, the prophylactic role of olanzapine on postoperative nausea and vomiting (PONV) has not been fully elucidated. This clinical trial aims to examine the effectiveness of olanzapine for preventing PONV. Methods Patients undergoing laparoscopic gynecological surgery at 5 university hospitals in Japan will be randomly assigned to receive either 5 mg of oral olanzapine or placebo 2 hours before the induction of anesthesia. All patients will receive intravenous dexamethasone at the induction of anesthesia. The primary outcome will be the incidence of postoperative nausea and vomiting within 24 hours after surgery. Secondary endpoints will include longitudinal changes in the incidence of postoperative nausea and vomiting and overall patient satisfaction. Discussion This trial will provide a high quality evidence whether olanzapine prevents PONV in gynecological laparoscopy patients at a high risk for PONV. Ethics and dissemination The trial was approved by the institutional review board of the each participating study site. Study findings will be disseminated through peer-reviewed publications and in conference presentations. Trial registration UMIN Clinical Trials Registry (UMIN-CTR) ID: 000022634, Registered on October 1, 2016 https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000026031