Nitrous oxide, an opioid addictive agent. Review of the evidence.

Pharmacologic evidence that nitrous oxide is addictive through direct interaction with the endogenous opioid system includes the possibility that it is a partial agonist and acts at the mu, kappa, and sigma opioid receptors. The medical and psychiatric complications of its abuse are discussed with special reference to the 32 cases of myeloneuropathy so far reported; other dangers are also mentioned. Notwithstanding the extremely low incidence of reported cases of nitrous oxide addiction compared with all other addictive substances, greater controls should be placed on its commercial availability to at least maintain its low level of abuse.