Varenicline in Combination With Nicotine Replacement Therapy for Smoking Cessation

Inclusion Criteria: 1. Current cigarette smokers, male and female, aged between 18-75 years (both limits inclusive), and who are motivated to stop smoking. 2. Have smoked on average at least 10 cigarettes per day during past year and during the month prior to screening, and no period of abstinence greater than 3 months in the past year. 3. Women of child-bearing potential (WCBP) may be included provided they are not pregnant, not nursing, and meet all of the following criteria: * instructed and agree to avoid pregnancy through 30 days after the last dose of study medication * negative screening test (beta-HCG) at screening * agree to use at least one birth control method (oral contraceptive, IUD, implantable or injectable contraceptive for at least 1 month prior to entering the study and will continue its use through at least 30 days after the last dose of study medication, or use a barrier method of contraception (p.e.condom, diaphragm with spermicide) while participating in the study through at least 30 days after the last dose of study medication; or abstinence. 4. Patients must have no serious or unstable disease in the past 6 months. 5. Patients must be able to be outpatients, to be assessed in a clinical setting, and be able and willing to comply with all study visits during the treatment and non-treatment periods. 6. Only one subject per household may participate. Exclusion Criteria: 1. Patients currently suffering from depression or who have been diagnosed with depression or treated with anti-depressants within the past 12 months. 2. Patients with a past of present history of psychosis, panic disorder, or bipolar disorder. 3. Patients with severe chronic obstructive pulmonary disease (COPD). 4. Patients with clinically significant cardiovascular disease in the past 6 months. such as myocardial infarction, coronary artery bypass graft (CABG), percutaneous transluminal coronary angioplasty (PTCA), severe or unstable angina, serious arrhythmia, and clinically significant ECG conduction abnormalities. 5. Patients with uncontrolled hypertension or a systolic blood pressure greater than 150mmHg or as diastolic pressure greater than 95mmHg at screening or baseline. 6. Patients with clinically significant neurological disorders or cerebrovascular diseases (for example, stroke, transient ischemic attack, etc.) in the past 6 months. 7. Patients with a history of clinically significant endocrine disorders or gastrointestinal diseases, including insulin dependent diabetes mellitus, uncontrolled hyperthyroidism, and active peptic ulcer. 8. Patients with clinically significant hepatic or renal impairment or other clinically significant abnormal laboratory test values. 9. Patients with a history of cancer (cured basal cell or squamous cell carcinoma of the skin allowed). 10. Patients with a history of clinically significant allergic reactions to drugs (for example, severe cutaneous and/or systemic allergic reactions). 11. Patients with a history of drug (except nicotine) or alcohol abuse or dependence within the past 12 months. 12. Patients with a body mass index (BMI) less than 15 or greater than 38 when wearing indoor clothing without shoes. No subject will be enrolled with a weight less than 45.5kg (100 pounds). 13. Patients previously enrolled in a study that included varenicline. 14. Patients having used nicotine replacement therapy within the last 6 months. 15. Patients taking another investigational drug within 30 days or 5 half-lives (whichever is longer) before the Baseline visit or within 30 days of study completion. 16. Use of prohibited medications: any antidepressants, including bupropion; antipsychotic agents; mood stabilizers; naltrexone; steroids (inhaled and topical steroids are permitted); insulin. 17. Patients who do not agree to completely abstain from using non-cigarette tobacco products (including for example, pipe tobacco, cigars, snuff, chewing tobacco, etc.) or marijuana during study participation. 18. Patients who intend to donate blood or blood components while receiving study drug or within 1 month of the completion of the study treatment. 19. Patients unable/or unlikely to comprehend and follow the study protocol, including patients unable and/or unwilling to participate in the non-treatment follow-up. Patients who, in the investigator's opinion, will be unlikely to commit to a 6 month-long study. 20. Other severe acute or chronic medical or psychiatric condition or laboratory abnormality that may increase the risk associated with study participation or investigational product administration or may interfere with the interpretation of study results and, in the judgment of the investigator, would make the subject inappropriate for entry into this study.