The purpose of this study is to determine the safety and tolerability of multiple doses of PF-05402536 and PF-06413367 in healthy adult smokers.

Inclusion Criteria:

• Current cigarette smokers
• Males or females of non-child bearing potential, who are between the minimum legal age for smoking (approximately 18 or 19 years, depending on local jurisdiction) and 55 years, inclusive, and who are motivated to stop smoking.
• Subjects must have smoked an average of at least 10 cigarettes per day during the past year and during the month prior to the prescreening assessment for entry, with no period of abstinence greater than 3 months in the past year.

Exclusion Criteria:

• Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, or neurologic disease that may compromise their ability to safely participate in the study.
• Active suicidal ideation or history of suicidal behaviors within the past 5 years prior to the screening visit.