The Effect of Naltrexone and Varenicline on Alcohol-Mediated Smoking Lapse

Inclusion Criteria: * ages 21-55 * ability to read and write in English * alcohol-drinking smokers Exclusion Criteria: * any significant current medical conditions that would contraindicate smoking * current DSM-IV abuse or dependence of other substances, other than nicotine dependence or alcohol abuse. * positive test result at intake appointments on urine drug screens conducted for opiates, cocaine, or benzodiazepines * women who are pregnant or nursing * suicidal, homicidal or evidence of current severe mental illness * participants prescribed any psychotropic drug in the 30 days prior to study enrollment * blood donation within the past 6 weeks * individuals seeking treatment for smoking cessation or drinking or have attempted to quit smoking or drinking within the past 3 months * specific exclusion for administration of naltrexone not specified above including chronic pain conditions necessitating opioid treatment, and evidence of significant hepatocellular injury as evidenced by SGOT or SGPT \> 3x normal or elevated bilirubin * known allergy to varenicline or taking H2blockers (e.g., Cimetidine) * participation within the past 8 weeks in other studies that involve additive blood sampling and/or interventional measures that would be considered excessive in combination with the current protocol