The effect of promethazine on postoperative pain: A comparison of preoperative, postoperative, and placebo administration in patients following total abdominal hysterectomy

Abstract

Background: Histamine receptors are involved in the development of inflammatory pain and hyperalgesia, and the use of antihistamines is advocated as an alternative for pain therapy and treatment of postoperative nausea and vomiting. We investigated the influence of timing of promethazine administration on postoperative pain outcomes. Methods: Ninety female patients undergoing total abdominal hysterectomy were randomly divided into three groups. All individuals received infusions of promethazine and normal saline before anaesthesia induction, and postoperatively the Pre group received promethazine 0.1 mg kg-1 before anaesthesia and saline postoperatively, and the Post group received saline before anaesthesia and promethazine 0.1 mg kg -1 postoperatively, while the Control group received two equivalent volumes of saline. Patients were treated using patient-controlled intravenous analgesia (PCA). The primary endpoint was pain intensity and morphine consumption. The secondary endpoint was postoperative nausea and vomiting. Results: Postoperative morphine usage was significantly lower in the Pre group (24.1 ± 3.9 mg) relative to the Post (30.0 ± 4.6 mg) and Control groups (32.1 ± 4.8 mg) during the first 24 h postoperatively (P < 0.05). The number and incidence of patients suffering from postoperative nausea in the first 24 h was six (21%), seven (23%), and 15 (47%) in the Pre, Post, and Control groups, respectively (P < 0.05). The number and incidence of patients vomiting in the first 24 h was three (10%), two (7%), and 10 (32%) in the Pre, Post, and Control groups, respectively (P < 0.05). The number of patients asking for rescue antiemetic in the first 24 h was one (3%), two (7%), and seven (22%) in the Pre, Post, and Control groups, respectively (P < 0.05). Conclusions: Our results suggest that preoperative administration of promethazine 0.1 mg kg-1 reduces postoperative morphine consumption compared with postoperative and placebo administration, and that use of promethazine reduces PONV and the number of patients asking for rescue antiemetic in the first 24 h after surgery when compared with placebo.