nitrous oxide + ketamine

Nitrous oxide + ketamine is a combination of two NMDA receptor antagonists used in anesthesia and being investigated for treatment-resistant depression. Both drugs are NMDA receptor antagonists with distinct properties that appear to have synergistic effects when used together. ## Pharmacology and Mechanism of Action Nitrous oxide (N₂O) and ketamine both act as antagonists of N-methyl-D-aspartate (NMDA) glutamate receptors, though through different mechanisms[1][6]. When combined, they produce a potentiated effect that is greater than either drug alone[1]. Ketamine is a cyclohexanone-derived general anesthetic that also has analgesic and hallucinogenic properties[2], while nitrous oxide is a colorless, odorless gas that has been used in medical settings for over 150 years[6]. ## Clinical Applications The combination is used in anesthesia, where ketamine is FDA-approved for enhancing the effects of low-potency substances such as nitrous oxide[5][8]. More recently, both drugs individually and in combination have been investigated for treatment-resistant depression due to their rapid-acting antidepressant properties[6][10]. ## Safety Considerations Research has shown that when ketamine and nitrous oxide are combined, there is a markedly augmented neurotoxic response compared to either drug given alone[1]. In animal studies, even ineffective doses of ketamine (20 mg/kg) combined with ineffective concentrations of nitrous oxide (75 vol%) resulted in robust neurotoxic reactions[1]. ## Development Status Both drugs individually have established uses in anesthesia, with ketamine approved by the FDA in 1970[4][10]. More recently, esketamine (the S-enantiomer of ketamine) was approved by the FDA in 2019 for treatment-resistant depression[4]. The combination therapy is being investigated for treatment-resistant depression, with promising initial studies showing rapid reduction in depressive symptoms[6][10].

Other names

N2O + ketamine