Premedication by controlled-release morphine

In a double-blind investigation the effect of oral controlled-release morphine (MST 30 mg) on pre-operative anxiety was assessed in 50 patients undergoing cholecystectomy. The effects on anaesthetic requirements and recovery, and postoperative pain were also studied. The patients who received morphine treatment were more sedated than those who received the placebo; however there was no significant difference in the anxiety scores for both groups of patients. During anaesthesia there were no significant differences between the groups, although the group of patients who received morphine required less anaesthetic supplement, and appeared to recover more slowly than the placebo group. One hour postoperatively, the morphine group had significantly less pain and were more sedated than the placebo group; the time to the administration of a postoperative analgesic was also significantly longer in the morphine group than the placebo group.