The Effects of Sedatives on Tobacco Use Disorder Version 2

Inclusion Criteria: * Smokes cigarettes daily for at least 2 years * Afternoon expired breath carbon monoxide at least 5 ppm or morning urinary cotinine at least 100 ng/ml * Negative urine drug screen for psychoactive drugs and negative breath alcohol Exclusion Criteria: * Have an unstable medical condition or stable medical condition that would interact with study drug or participation, including chronic pulmonary disease, coronary artery disease, current brain tumor, current increased intracranial pressure or impaired consciousness * History of serious head trauma or neurological disorder (e.g., seizure disorder) * Have any of the following: hypertension (i.e., systolic \>140 mm Hg and/or diastolic \>90 mm Hg on three separate measures; systolic \>170 or diastolic \> 110 on any occasion), pre-existing severe gastrointestinal narrowing (pathologic or iatrogenic). * Use of drugs that would interact with study drug or increase risk of adverse events * Among women, pregnancy or lactation