ACUTE REINFORCING EFFECTS OF LOW-DOSE NICOTINE NASAL SPRAY IN HUMANS

Tobacco smoking behavior is reinforced by nicotine intake, but there h as been little human research examining self-administration of nicotin e per se, isolated from tobacco. In this study, 10 smokers (5 men, 5 w omen) who wanted to quit smoking sampled 0 (placebo), 0.75, and 1.5 ug /kg/spray nicotine via nasal spray during separate lab sessions before engaging in a free choice session, involving ad lib access to all thr ee spray doses. Subjects also ad lib smoked during another session. Fo r the group as a whole, neither nicotine spray dose was self-administe red significantly more than placebo during the free choice session, su ggesting low abuse potential. However, 4 of 10 subjects self-administe red 1.5 ug/kg/spray on more than 50% of all sprays (vs. 33% chance) an d were designated nicotine ''choosers,'' while the others were ''nonch oosers.'' Choosers responded to initial nicotine spray exposure during sampling sessions with greater positive subjective effects (similar t o their responses to tobacco smoking), smoked more during the ad lib s moking session (i.e., self-administered more nicotine via tobacco smok ing), and tended to be more heavily dependent smokers. They did not re port greater withdrawal relief or less aversive effects from nicotine, suggesting their greater nicotine choice reflected greater positive r einforcement rather than negative reinforcement. These results are con sistent with the few existing studies demonstrating that acute nicotin e intake per se, in the absence of tobacco, may be reinforcing in some smokers. Copyright (C) 1997 Elsevier Science Inc.