Adult smokers ( N = 315 ) enrolled in a 12-week , double-blinded , placebo-controlled trial of 50mg 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 6months ) .