Nitrous oxide

Last revised by Daniel J Bell on 26 Sep 2023

Nitrous oxide (N2O) is an odorless and colorless gas that can cause a state of euphoria.

Nitrous oxide is the least powerful of the inhalational anesthetic agents, needing up to 104% concentration to reach 1 minimum alveolar concentration (MAC). Thus, it is usually admixed with a more volatile and potent anesthetic agent. It is commonly used in obstetric and emergency settings.

Mechanism of action
  • anesthetic effect

    • non-competitive NMDA inhibition in CNS

  • analgesic effect

    • release of endogenous opioids

  • anxiolytic effect

    • GABA-A activation

  • central sympathomimetic effect


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