Two double-blind, randomized, crossover trials were conducted to study whether the benzodiazepine antagonist, flumazenil, would interact with the subjective and psychomotor effects of nitrous oxide in healthy volunteers. In both experiments, eight subjects inhaled 30% nitrous oxide in oxygen for 35 min and were challenged, 10 min into the inhalation, with flumazenil. Experiment 1 tested a range...