The present study used a double-blind , randomized , 22 medication design , testing varenicline alone ( VAR ; 1 mg twice daily ) , low dose naltrexone alone ( L-NTX ; 25 mg once daily ) , varenicline plus naltrexone , and placebo for effects on cigarette craving and subjective response to alcohol and cigarettes in a sample ( n = 130 ) of heavy-drinking daily smokers ( 10 cigarettes/day ) .