Pharmacology · single question
What is the primary mechanism of action of nitrous oxide?
Show answer and explanation
Correct answer: A. NMDA receptor inhibition
- A. Correct. Nitrous oxide acts principally as a non-competitive NMDA (glutamate) receptor ANTAGONIST, which accounts for its analgesic and anesthetic effects. Its anxiolytic effect involves some GABA-A activity, and its analgesia also involves release of endogenous opioid peptides — but NMDA antagonism is the primary mechanism. Contrast with ketamine, which is also an NMDA antagonist.
- B. Nitrous oxide triggers endogenous opioid release indirectly but does not directly activate opioid receptors.
- C. GABA-A activation is the mechanism of benzodiazepines, barbiturates, and most volatile anesthetics — a secondary contributor for N2O at most.
- D. Sodium channel blockade is the mechanism of LOCAL anesthetics.