Ketamine's primary mechanism of action is which of the following?

Ketamine's primary mechanism of action is which of the following?

• A. NMDA Receptor Antagonist
• B. GABA Receptor Agonist
• C. Opioid Receptor Agonist
• D. NMDA Receptor Agonist

Answer: (A)

Ketamine’s primary action is blocking NMDA receptors, making it a noncompetitive NMDA receptor antagonist. These receptors mediate much of the brain’s excitatory glutamate signaling, so when ketamine occupies the receptor channel (especially when the channel is open), it prevents calcium influx and dampens excitatory transmission. This disruption produces dissociative anesthesia, analgesia, and amnesia characteristic of ketamine. It’s not a GABA receptor agonist (that would underlie drugs like propofol or benzodiazepines), nor does it activate NMDA receptors (agonist action would have the opposite effect). While other systems may contribute to analgesia or side effects, the defining, primary mechanism is NMDA receptor antagonism.

Ketamine’s primary action is blocking NMDA receptors, making it a noncompetitive NMDA receptor antagonist. These receptors mediate much of the brain’s excitatory glutamate signaling, so when ketamine occupies the receptor channel (especially when the channel is open), it prevents calcium influx and dampens excitatory transmission. This disruption produces dissociative anesthesia, analgesia, and amnesia characteristic of ketamine. It’s not a GABA receptor agonist (that would underlie drugs like propofol or benzodiazepines), nor does it activate NMDA receptors (agonist action would have the opposite effect). While other systems may contribute to analgesia or side effects, the defining, primary mechanism is NMDA receptor antagonism.