Free-Base Nicotine or Nicotine Salt e-Liquids in Current E-Cigarette Smokers, PeloPET Study

PRIMARY OBJECTIVES: I. To examine the influence of nicotine form on puffing behavior and abuse liability. II. To evaluate the influence of nicotine form and concentration on nicotine distribution in the brain and respiratory tract. OUTLINE: VISIT 1: Patients sample 4-liquids to determine whether they can vape the unflavored e-liquid without coughing Patients are randomized to 1 of 2 arms. ARM I: VISIT 2: Patients receive 1 puff of tobacco flavored or unflavored protonated e-liquid and undergo 0-15 minutes (min) head and 5 min chest positron emission tomography (PET)/computed tomography (CT) and then 0-15 min chest and 5 min head PET/CT. About 2 hours post initial PET/CT, patients receive a second puff of tobacco flavored or unflavored protonated e-liquid and undergo 0-15 min chest and 5 min head PET/CT and then 0-15 min head and 5 min chest PET/CT. VISIT 3: Patients receive 1 puff of tobacco flavored or unflavored unprotonated e-liquid and undergo 0-15 min head and 5 min chest PET/CT and then 0-15 min chest and 5 min head PET/CT. About 2 hours post initial PET/CT, patients receive a second puff of tobacco flavored or unflavored unprotonated e-liquid and undergo 0-15 min chest and 5 min head PET/CT and then 0-15 min head and 5 min chest ARM II: VISIT 2: Patients receive 1 puff of tobacco flavored or unflavored unprotonated e-liquid and undergo 0-15 min head and 5 min chest PET/CT and then 0-15 min chest and 5 min head PET/CT. About 2 hours post initial PET/CT, patients receive a second puff of tobacco flavored or unflavored unprotonated e-liquid and undergo 0-15 min chest and 5 min head PET/CT and then 0-15 min head and 5 min chest. VISIT 3: Patients receive 1 puff of tobacco flavored or unflavored protonated e-liquid and undergo 0-15 min head and 5 min chest PET/CT and then 0-15 min chest and 5 min head PET/CT. About 2 hours post initial PET/CT, patients receive a second puff of tobacco flavored or unflavored protonated e-liquid and undergo 0-15 min chest and 5 min head PET/CT and then 0-15 min head and 5 min chest PET/CT.