Preoperative and postoperative dextromethorphan provides sustained reduction in postoperative pain and patient-controlled epidural analgesia requirement: a randomized, placebo-controlled, double-blind study in lower-body bone malignancy-operated patients.

BACKGROUND

Pain is mediated centrally by N-methyl-D-aspartate (NMDA) receptors. The antinociceptive effects of preincision dextromethorphan (DM), an NMDA antagonist, have been demonstrated in surgical patients under general or epidural anesthesia. The authors investigated the effects of DM on postoperative pain and other parameters in patients undergoing surgery for bone malignancy under standardized combined general and epidural anesthesia using patient-controlled epidural analgesia (PCEA) postoperatively.

METHODS

Patients received placebo or DM 90 mg (30 patients per group) in a double-blind manner preoperatively and on each of the two following days. Postoperative PCEA consisted of 1.6 mg ropivacaine plus 4 microg/mL fentanyl both continuously and by demand up to 96 hours, starting when subjective pain intensity was greater than or equal to 4/10 (visual analog score). Rescue drugs on demand (paracetamol or dipyrone orally) were also available.

RESULTS

The DM patients experienced about 50% (P < 0.01) less pain than their placebo counterparts for more than 2 postoperative days and they rated their overall maximal pain intensity by one-half that estimated by the placebo-treated patients (P < 0.01). The DM group also consumed 30-50% less epidural analgesics than the total amount consumed by the placebo-medicated group (P < 0.01) and demanded significantly (P < 0.05) fewer rescue drugs on the first postoperative day. They were less sedated (40-60%, P < 0.01) and reported 50% fewer overall side effects (P < 0.05). The groups were similar for the need for urinary catheterization, time of first ambulation, and/or discharge home.

CONCLUSIONS

A 3-day DM administration is associated with better pain reduction in patients undergoing surgery for bone malignancy under combined general and epidural anesthesia with postoperative PCEA compared with placebo without increasing side effects.