Perioperative Dextromethorphan as an Adjunct for Postoperative Pain A Meta-analysis of Randomized Controlled Trials

Background: N-methyl-d-aspartate receptor antagonists have been shown to reduce perioperative pain and opioid use. The authors performed a meta-analysis to determine whether the use of perioperative dextromethorphan lowers opioid consumption or pain scores. Methods: PubMed, Web of Science, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Pubget, and EMBASE were searched. Studies were included if they were randomized, double-blinded, placebo-controlled trials written in English, and performed on patients 12 yr or older. For comparison of opioid use, included studies tracked total consumption of IV or intramuscular opioids over 24 to 48 h. Pain score comparisons were performed at 1, 4 to 6, and 24 h postoperatively. Difference in means (MD) was used for effect size. Results: Forty studies were identified and 21 were eligible for one or more comparisons. In 848 patients from 14 trials, opioid consumption favored dextromethorphan (MD, -10.51 mg IV morphine equivalents; 95% CI, -16.48 to -4.53 mg; P = 0.0006). In 884 patients from 13 trials, pain at 1 h favored dextromethorphan (MD, -1.60; 95% CI, -1.89 to -1.31; P < 0.00001). In 950 patients from 13 trials, pain at 4 to 6 h favored dextromethorphan (MD, -0.89; 95% CI, -1.11 to -0.66; P < 0.00001). In 797 patients from 12 trials, pain at 24 h favored dextromethorphan (MD, -0.92; 95% CI, -1.24 to -0.60; P < 0.00001). Conclusion: This meta-analysis suggests that dextromethorphan use perioperatively reduces the postoperative opioid consumption at 24 to 48 h and pain scores at 1, 4 to 6, and 24 h.