Randomized, double-blind study comparing postoperative effects of treatment timing with histamine H2-receptor antagonist cimetidine

Background: The purpose of this study was to evaluate the effect of timing of preoperative, postoperative, and placebo administration of the H-2-antagonist cimetidine on postoperative pain management and the incidence of side-effects. Methods: One hundred and twenty ASA I to II patients, undergoing major gynaecological abdominal surgery, were randomly divided into three groups, and received a standardized general anaesthesia. The patients in the preoperative ('Pre') group received an intravenous infusion of cimetidine 4 mg kg(-1) prior to anaesthesia induction; the postoperative ('Post') group received the same volume of normal saline. Postoperatively, the patients in the Post group received an intravenous infusion of cimetidine 4 mg kg(-1) the patients in the Pre group received the same volume of normal saline. The Control group received the same volume of normal saline prior to anaesthesia induction and after the end of operation. Postoperatively, all patients were treated with a patient-controlled intravenous analgesia system, which was programmed to deliver 1 mg of morphine on demand for three consecutive days. Results: Pain intensity, morphine consumption, sedation score, and side-effects were recorded and evaluated. We found no difference among the three groups with respect to pain intensities, morphine usage, sedation scores, and the incidence of nausea, vomiting, pruritus, or dizziness. Conclusions: Our results suggested that neither preoperative nor postoperative administration of cimetidine 4 mg kg(-1) provided a pre-emptive or preventive analgesic advantage for postoperative pain or morphine consumption, and that the use of cimetidine failed to reduce the incidence of nausea or vomiting.