Perioperative dextromethorphan reduces postoperative pain after hysterectomy

We studied the effect of dextromethorphan, an N-methyl-D-aspartate antagoni st, on analgesic consumption and pain scoring after abdominal hysterectomy. In this double-blinded study, 50 patients were randomized into two groups. Group DM was given oral dextromethorphan 40 mg with their premedication, t hen 40 mg three times per day for the next 2 days. Group P received placebo at identical times. Postoperative analgesic requirements were assessed usi ng a patient-controlled analgesia system and subsequent oral analgesic inta ke using a set protocol. Pain was assessed at rest and on movement using a visual analog scale 4, 24 48, and 72 h after the operation. Median pain sco res at rest were significantly lower at 48 and 72 h and also for the sum of all resting pain scores. Mean morphine consumption was less in Group DM (1 .1 vs 1.5 mg/h; P = 0.054) Usage of oral diclofenac given every 8 h as need ed, did not differ between groups, but consumption of codydramol (paracetam ol 500 mg and dihydrocodeine 10 mg) was significantly less in Group DM. We conclude that the use of oral dextromethorphan has an analgesia-sparing eff ect and some beneficial effects on pain scoring at rest after abdominal hys terectomy. Implications: Patients given dextromethorphan before and after s urgery had a significant reduction in some pain scores at rest, but not on movement. There was a trend to lower morphine requirements in the first 24 h. Over the next 48 h, oral analgesic usage was significantly reduced.