Inclusion Criteria:

Male/Female subjects ages 21-45 years inclusive, with a smoking history of at least 15 cigarettes daily (greater than or equal to 50) for at least 1 yr. Subject is in good health as verified by medical history, screening examination, and screening laboratory tests as outlined above. Subject has provided written informed consent to participate in the study and is motivated to stop smoking. Subject has experienced at least 4 withdrawal symptoms upon abstinence.

Exclusion Criteria:

History of myocardial infarction, angina pectoris, sustained or episodic cardiac arrhythmias, symptomatic peripheral vascular disease, current peptic ulcer disease or any other medical condition which the physician investigator deems inappropriate for subject participation. Insulin-dependent diabetes. Pregnant or lactating, or not using adequate birth control methods. Requirement of any form of regular psychotropic medication (antidepressants, antipsychotics, or anxiolytics) and recent psychiatric history (less than 1yr). Chronic use of systemic steroids or antihistamines. Abuse of alcohol or any other recreational or prescription drug (more than 3 drinks per day or 21 drinks per wk). use of any other nicotine products, including smokeless tobacco, cigars and nicotine replacement products. Inability to fulfill all scheduled visits and examination procedures throughout the study period. History of schizophrenia or manic depressive disorder. Recent history of other psychiatric illness (less than 1yr since last episode of major depressive episode).