Abstract
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 (N~2~ O) one or more times in succession. The effects of such an inhalation mode (i.e. brief inhalation of higher concentrations of N~2~ O) 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 N~2~O in healthy volunteers. We used a prospective, placebo‐controlled, double‐blind, crossover design in which N~2~O was administered to subjects for 45 s in concentrations of O (oxygen‐placebo), 20, 40, and 80 per cent. A number^2^ 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 N~2~O (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 postinhalation (2.5 min) and pre‐inhalation (baseline), but the self‐reported time course of effects of N~2~O 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 N~2~O produce a range of subjective effects which is consistent with its recreational use (abuse).