Lack of effects of ethanol pretreatment on the abuse liability of nitrous oxide in light and moderate drinkers.

Abstract

To determine effects of ethanol-use history and ethanol pretreatment on abuse liability of nitrous oxide (N(2)O). Placebo-controlled, double-blind, cross-over design evaluating effects of N(2)O, 0% (100% O(2), placebo) and 30% (in O(2)), in the presence of three doses of ethanol: 0 g/kg (placebo), 0.35 g/kg and 0.7 g/kg. Subjects sat in a reclining chair in a hospital laboratory. Eight healthy light drinkers (one drink or less/week) and eight healthy moderate drinkers (seven or more drinks/week) with no history of drug dependence completed the study. On three sessions (1, 3, 5) subjects drank a beverage that contained one of the three ethanol doses, then sampled for 10 minute each 0% and 30% N(2)O. During choice sessions (2, 4, 6), subjects received the same ethanol dose as in the previous session, then chose six times, once every 5 min, between 0% and 30% N(2)O. Subjective (self-reported) drug effects, reinforcing effects of N(2)O as assessed by choice, and psychomotor effects were measured. Choice of N(2)O did not differ between light (mean = 3.4 choices) and moderate (mean = 3.2 choices) drinkers and was not influenced by ethanol dose (0 g/kg: 3.3 choices, 0.35 g/kg: 3.5 choices, 0.7 g/kg: 3.1 choices). Subjective effects of N(2)O also did not depend on ethanol-use history or ethanol dose. N(2)O liking and desire to inhale the drug again were positively correlated with N(2)O choice. Ethanol pretreatment and ethanol-use history had no effect on the abuse liability of N(2)O as assessed in the present study.