EFFECTS OF NICOTINE ON METHADONE SELF-ADMINISTRATION IN HUMANS

The effects of nicotine abstinence, ad libitum smoking, and 0, 2, and 4 mg nicotine gum on methadone self-administration were investigated. Five methadone-maintained patients with a history of smoking (18-30 ci garettes/day) were recruited as subjects. Upon arrival expired carbon monoxide levels were measured to confirm self-reported abstinence of 1 0-12 h. At 30 min prior to the methadone self-administration session, two response options were concurrently available. When a 64-button pre ss requirement (FR64) was completed, 10 mi of 0.054 mg/ml methadone so lution, or vehicle, was delivered. Immediately following, and 30, 60, 90, and 120 min after the self-administration session, expired carbon monoxide levels and typical symptoms of nicotine withdrawal were asses sed. Relative to abstinence, subjects consumed more methadone followin g the 4-mg nicotine gum and ad libitum smoking conditions. Ratings of cigarette craving were significantly less following ad libitum smoking or administration of 4-mg nicotine gum, than following abstinence. Im plications for understanding opioid and nicotine interactions are disc ussed. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.