Are N methyl d aspartate receptor antagonists useful for neuropathic pain?
Patients who do not respond to the treatments discussed previously could consider ketamine (intranasal formulation), memantine, or dextromethorphan. Despite having the usual indications of anesthesia, treatment of Alzheimer’s disease, or cough suppression, respectively, each of these drugs causes some degree of NMDA receptor antagonism. Ketamine IV has also been studied in CRPS and phantom limb pain, with inconsistent results. Based on current meta-analysis, no definitive conclusion on the efficacy of NMDA receptor antagonists in chronic neuropathic pain can be made. Given the NMDA receptor’s role in spontaneous pain, allodynia, and hyperalgesia, it remains an area of research.