Sevoflurane, a volatile anesthetic, was tested at subanesthetic concentrations (0.2, 0.4, 0.6%) against placebo and 30% nitrous oxide in moderate-drinking volunteers. Neither drug was chosen significantly more often than chance: nitrous oxide was chosen by 71% of subjects, and sevoflurane by 50%, 57%, and 50% at the three concentrations. Both drugs impaired psychomotor performance and altered mood, with some differences in subjective effects. Although sevoflurane did not act as a reinforcer for most participants, those who chose it reported more positive subjective effects during sampling, suggesting it can function as a reinforcer in some individuals.
Recreational users sometimes combine ethanol and nitrous oxide (N2O), but their combined subjective effects were unstudied. In 11 volunteers, ethanol (0, 0.25, or 0.5 g/kg) was consumed, followed 15 minutes later by inhaling 30% N2O or placebo oxygen for 35 minutes. Thirty minutes into inhalation, subjects immersed a forearm in icy water for 3 minutes. Ethanol increased ratings of feeling drug effect and drunkenness. N2O altered mood, impaired cognitive and psychomotor performance, and reduced pain reports. Ethanol potentiated some N2O effects, and the combination produced effects neither drug alone did, but ethanol did not enhance N2O's analgesic effects. The data did not convincingly show the combination had greater abuse liability than N2O alone at the tested doses.