The present study used a double-blind , randomized , 22 medication design , testing varenicline alone ( VAR ; 1mg twice daily ) , naltrexone alone ( NTX ; 25mg once daily ) , varenicline plus naltrexone , and placebo for effects on neural activation to cigarette cues in a sample ( n = 40 ) of heavy drinking daily smokers ( 10 cigarettes/day ) .