Naloxone Fails to antagonize nitrous oxide analgesia for clinical pain

Abstract
In 30 patients with dental postoperative pain we tested the hypothesis that the analgesic effects of nitrous oxide (N2O), a mild analgesic, may be mediated via endogenous opioids. Using the visual analog scale to assess pain, significant analgesia was induced by 33% N2O. N2O-induced analgesia was not significantly antagonized by 10 mg of intravenous naloxone. In the setting of clinical pain there appears to be little if any contribution of endogenous opioids to N2O-induced analgesia.