Dextromethorphan reduces immediate and late postoperative analgesic requirements and improves patients' subjective scorings after epidural lidocaine and general anesthesia

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.

Preoperative oral dextromethorphan does not reduce pain or morphine consumption after open cholecystectomy

BACKGROUND

Dextromethorphan, the D-isomer of the codeine analog levorphanol, is a weak, noncompetitive N-Methyl-D-Aspartate (NMDA) receptor antagonist. It has been suggested that NMDA receptor antagonists induce preemptive analgesia when administered before tissue injury occurs, thus decreasing the subsequent sensation of pain.

MATERIALS AND METHODS

The study was conducted in the Dr. Ali Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran, between February 2005 and December 2006. In this study, 72 patients scheduled for elective cholesyctectomy were randomized into three groups to receive either oral dextromethorphan 45 mg (Group D45 = 24), dextromethorphan 90 mg (Group D90 = 24), or placebo (Group C, n = 24), as premedication, 120 minutes before surgery. A visual analog scale (VAS) for pain of each patient was measured at arrival in the ward and six and 24 hours after surgery.

RESULTS

The demographic characteristics of patients, ASA physical status class, duration of surgery, and the basal VAS pain score were similar in the two groups. There was no significant difference in the mean of the VAS pain scores measured over time or morphine consumption among the three groups.

CONCLUSION

Dextromethorphan 45 mg and 90 mg, administrated orally, two hours before surgery, had no effect on postoperative morphine requirement and pain intensity.

N-methyl-D-aspartate- enhanced analgesia

A greater understanding of the mechanisms that produce chronic pain states has led to a search for novel agents with the potential to produce analgesia by directly modulating specific processes involved in the transduction, transmission, modulation, perception, and encoding of pain. It is hoped that compounds directed at these specific targets will produce better analgesics with an improved side-effect profile. The N-methyl-D-aspartate receptor has been shown to play an important role in pain modulation and has become a target for potential analgesic compounds. Antagonists to the N-methyl-D-aspartate receptor were antinociceptive in a number of animal models, and analgesic in experimental pain models in healthy subjects and in chronic neuropathic pain syndromes. In addition, these compounds have demonstrated the ability to prevent the development of tolerance to opioid analgesic therapy. This has led to investigations of therapies that combine an opioid agonist with an N-methyl-D-aspartate receptor antagonist.