Subjective And Psychomotor Effects Of Bolus Doses Of Nitrous-Oxide In Humans

Nitrous oxide, commonly used in medical settings for its anxiolytic, analgesic, and anesthetic effects, is also used recreationally. One method of using this agent recreationally is to inhale a pure bolus of nitrous oxide (N2O) one or more times in succession. The effects of such an inhalation mode (i.e. brief inhalation of higher concentrations of N2O) have not been adequately characterized. The present experiment examined the subjective and psychomotor effects of short duration (or bolus) administrations of a range of concentrations of N2O in healthy volunteers. We used a prospective, placebo-controlled, double-blind, crossover design in which N2O was administered to subjects for 45 s in concentrations of 0 (oxygen-placebo), 20, 40, and 80 per cent. A number of subjective effects, including increased VAS ratings of 'high,' 'tingling,' 'stimulated,' and 'confused' and increased 'euphoria' and 'psychedelic effects' scores on an Inhalant Drug Effects post-session questionnaire were found with higher concentrations of N2O (i.e. 40 per cent and 80 per cent). Subjective effects were short-lived and had usually dissipated within several minutes of inhalation. Psychomotor performance did not differ between the first time that we measured it post-inhalation (2.5 min) and pre-inhalation (baseline), but the self-reported time course of effects of N2O suggested that we tested post-inhalation psychomotor performance when effects were subsiding (i.e. not when they were at their peak). We conclude that bolus concentrations of N2O produce a range of subjective effects which is consistent with its recreational use (abuse).