A Comparative Study of the Effect of Oral Dextromethorphan and Placebo on the Pain After Vitrectomy Surgery: A Double-Blind, Placebo-Controlled, Randomized Clinical Trial

Postoperative pain is a major complication in patients undergoing eye surgery. N-methyl-D-aspartate (NMDA) receptor antagonists are widely used to manage postoperative pains. Dextromethorphan, as an NMDA antagonist, is commonly used as an oral drug. This study was conducted to evaluate the effect of Dextromethorphan on post-operation pain and sedative effect in comparison to placebo. A double-blinded, placebo-controlled, randomized clinical trial, upon 60 patients undergoing vitrectomy surgery was done. Thirty patients received 30 mg oral Dextromethorphan before the operation, and 30 patients received a placebo. Post-operation pain and sedation were evaluated after zero, one, two, and six hours. Post-operation pain was significantly lower in patients who received Dextromethorphan at zero, one, and two hours after operation (P < 0.001); however, not at six hours after operation (P = 0.11). Sedative effect was higher in the Dextromethorphan group at zero (P = 0.03) and one hour (P = 0.01) after operation. Prescribing oral Dextromethorphan before a vitrectomy surgery could reduce postoperative pain. It also has postoperative sedation effects.