A Comparative Study on the Efficacy of Oral Memantine and Placebo for Acute Postoperative Pain in Patients Undergoing Dacryocystorhinostomy (DCR)

BACKGROUND Memantine is an N-methyl-D-Aspartate (NMDA) antagonist. By transferring acute postoperative pain, the NMDA channels may lead to active excess and neuropathic pain. Objectives: This study attempted to investigate the effect of preoperative use of single oral dose of memantine in controlling Dacryocystorhinostomy (DCR) postoperative pain. METHODS A double-blind clinical trial was conducted on 60 patients undergoing DCR. On arrival at the operating room, the memantine group received 20 mg of oral memantine and the control group received placebo. The severities of pain by visual analogue scale (VAS) and sedation by Ramsy Scale were measured immediately 1, 2, and 6 hours after the operation. The drug's side effects were recorded. RESULTS The pain scores of patients in the recovery in 1, 2, and 6 hours after operation were significantly lower in the memantine group than the placebo group (P < 0.001). The sedation score, 1 hour after the operation, was significantly greater in the memantine group than the placebo (P < 0.001). The sedation scores did not have any statistically significant difference in recovery and 2 hours after surgery between the two groups. Moreover, the sedation scores in 6 hours after the surgery were identical in the two groups. CONCLUSIONS The oral single-dose 20 mg of memantine administered before DCR can reduce postoperative pain compared with placebo.