Morphine versus nalbuphine for open gynaecological surgery: A randomized controlled double blinded trial

Introduction. Pain is the commonest morbidity after open surgical procedures. The most effective treatment of postoperative pain is opioid therapy. Morphine, the commonly used opioid, is associated with many side effects including respiratory depression, sedation, postoperative nausea vomiting, and pruritus. Nalbuphine, on the other hand, is known to cause less respiratory depression. Thus this study was undertaken to compare the intraoperative and postoperative analgesic efficacy and side effect profile of the two drugs. Methodology. 60 patients undergoing open gynaecological surgery were randomized to receive either morphine (Group M) or nalbuphine (Group N) in the intraoperative and postoperative period. Intraoperative analgesic efficacy (measured by need for rescue analgesics), postoperative pain by visual analogue scale, and side effects like postoperative nausea, vomiting, sedation, respiratory depression, and pruritus were compared in both groups. Intraoperative and postoperative heart rate and blood pressure were also compared between the groups. Results. Need for intraoperative analgesia was significantly more in Group N (P=0.023). Postoperative VAS scores were significantly different between the groups at various time points; however, none of the patients required any rescue analgesia. The incidence of various side effects was not significantly different between the groups. The haemodynamic profile of patients was comparable between the groups in both intraoperative and postoperative period. Conclusion. Nalbuphine provides less effective intraoperative analgesia than morphine in patients undergoing open gynaecological surgery under general anaesthesia. Both drugs, however, provided similar postoperative analgesia and had similar haemodynamic and side effect profile.