Multiple Dose, Dose Escalation Study of Varenicline Controlled Release Formulation in Adult Smokers

Inclusion Criteria: * Healthy male and/or female subjects between the ages of 18 and 55 years, inclusive. Healthy is defined as no clinically relevant abnormalities identified by a detailed medical history, full physical examination, including blood pressure and pulse rate measurement, 12 lead ECG and clinical laboratory tests. * Currently smoking and have smoked an average of at least 10 cigarettes per day during the past year, with no period of abstinence greater than 3 continuous months in the past year. Exclusion Criteria: * Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurologic, or allergic disease (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at time of dosing). * Pregnant or nursing women are excluded; women of childbearing potential (WOCBP) who are unwilling or unable to use an acceptable method of contraception as outlined in the protocol from at least 14 days prior to study medication administration until completion of protocol-required procedures are excluded. * Subjects with an estimated creatinine clearance (CLcr) \<80 mL/min derived using the method of Cockcroft and Gault.