Ineffectiveness of dextromethorphan in cancer pain

Experimental studies have indicated that N-methyl-D-aspartate (NMDA) receptor antagonists may be effective analgesics in a wide variety of chronic pain states. The mechanism is presumed to be related to decreased firing of dorsal horn neurons after constant repeated C-fiber stimulation. Dextromethorphan (DM), a potent NMDA antagonist with a good safety profile, may be a promising agent for the treatment of persistent pain. An open-label randomized trial was designed to examine the effects of combining DM with NSAIDs, dextropropoxyphene, or morphine in cancer patients with pain. Patients who required a change in the step of the World Health Organization's (WHO) analgesic ladder because of a …