NMDA Antagonists
Ketamine is a useful NMDA receptor antagonist that provides a strong analgesic effect even at sub-anesthetic doses, and has an established role in both acute and chronic pain management. Intravenous ketamine infusions should be considered early for pain complaints in hospitalized chronic pain patients, and is particularly useful in patients with a tolerance to opioids, neuropathic pain, or evidence of central sensitization. Side effects are typically dose dependent; significant side effects are rare. Mild psychomimetic effects may occur but quickly dissipate with cessation of infusion and are generally temporized by concurrent use of benzodiazepines. Memantine is another NMDA antagonist taken orally for the treatment of Alzheimer’s disease. Memantine has been used off-label for acute and chronic pain indications.
