Abstract
BACKGROUND: Heavy drinking smokers (HDS) have more difficulty quitting smoking than lighter drinkers or abstainers. The opioid antagonist naltrexone may improve smoking quit rates and reduce alcohol use in drinker-smokers, but its relative efficacy in smokers with a range of drinking patterns is unknown. The current study tested the hypothesis that HDS would show differential benefit of naltrexone versus placebo relative to moderate-to-light or nondrinking smokers in terms of improving smoking outcomes and reducing alcohol consumption. METHODS: Adult smokers (N = 315) enrolled in a 12-week, double-blinded, placebo-controlled trial of 50 mg naltrexone for smoking cessation were categorized into subgroups based upon past 6-month drinking patterns: HDS (n = 69; i.e., averaged ≥2 heavy drinking episodes per month), moderate-to-light drinking smokers (n = 204, i.e., consumed 1 drink up to a maximum of <2 heavy drinking episodes per month on average), or nondrinking smokers (n = 42, no alcohol consumed in the past 6 months). The groups were compared on the main study outcomes of biochemically verified prolonged abstinence quit rates (i.e., no smoking weeks 2 to 12), and smoking urge and alcohol use (drinks/wk) during treatment. RESULTS: Naltrexone significantly increased 12-week smoking abstinence rates and decreased smoking urge and alcohol use among HDS, but not moderate-to-light or nondrinking smokers. Mediation analyses in HDS revealed that naltrexone's effect on smoking urge during the first 4 weeks of treatment mediated its effect on quit rates. CONCLUSIONS: HDS appear to be particularly sensitive to naltrexone effects on smoking and drinking outcomes. This group may represent an important target for adjunctive treatment with naltrexone to optimize smoking cessation outcomes.