What is the role of NMDA receptor antagonists like ketamine in pain management?

• A. They reduce central sensitization by blocking NMDA receptors
• B. They have no effect on central sensitization
• C. They primarily act on GABA receptors
• D. They increase glutamate release to relieve pain

Answer: (A)

Blocking NMDA receptors reduces central sensitization, a process where the nervous system becomes highly responsive to pain after injury. Ketamine, as an NMDA receptor antagonist, prevents calcium influx through these channels when glutamate binds, dampening the excitatory signaling that drives wind-up and long-term changes in dorsal horn neurons. This lessens hyperalgesia and allodynia, providing analgesia that can complement opioids and reduce opioid requirements, especially in perioperative or neuropathic pain. It doesn’t act primarily on GABA receptors, nor does its analgesia come from increasing glutamate release; the benefit comes from blocking the NMDA-mediated excitatory cascade. Be aware of potential dissociative or psychotomimetic side effects at higher or certain doses, which guides careful dosing and patient selection.