Which statement best describes ketamine's antidepressant action?

• A. It is a rapid-acting antidepressant
• B. It cures depression instantly
• C. It has no side effects
• D. It is a monoamine oxidase inhibitor

Answer: (A)

Ketamine’s antidepressant action is characterized by rapid onset. Unlike traditional antidepressants that often take weeks to show benefit, ketamine can produce significant mood improvement within hours after a subanesthetic dose, which is especially useful in acute suicidality and treatment-resistant depression. This rapid effect does not mean a cure; symptoms can return after days to weeks without maintenance treatment. Mechanistically, the effect stems from NMDA receptor antagonism leading to a surge of glutamate signaling and downstream activation of AMPA receptors, which promotes synaptic plasticity in mood-regulating brain circuits via BDNF and mTOR pathways. Side effects and safety concerns, including dissociation, perceptual changes, blood pressure changes, and abuse potential, require careful clinical use. Therefore, describing it as a rapid-acting antidepressant best captures its distinctive clinical profile.