Characterization of Biomarkers of Tobacco Exposure, Urge-to-Smoke Following Exclusive and Dual Ad Lib Use of Electronic Cigarettes

This is a randomized, open-label, forced-switch, parallel, proof-of-concept study to assess exposure to biomarkers of tobacco exposure following short-term ad lib use of three blu e-cigarette products. The primary objectives of this study are to: 1. Compare changes in selected urine and blood biomarkers of tobacco exposure within cohorts following a 5-day forced-switch from usual brand conventional combustible cigarettes to exclusive use of blu e-cigarettes, dual use of blu e cigarettes and the subject's usual brand combustible cigarette, or smoking cessation. 2. Compare changes in selected urine and blood biomarkers of tobacco exposure among cohorts following a 5-day forced-switch from usual brand conventional combustible cigarettes to exclusive use of a blu e cigarette, dual use of a blu e-cigarette and the subject's usual brand combustible cigarette, or smoking cessation. The secondary objectives of this study are to: 1. Compare changes in selected physiological endpoints affected by tobacco exposure within cohorts during a 5-day forced-switch from usual brand conventional combustible cigarettes to exclusive use of blu e cigarettes, dual use of blu e cigarettes and the subject's usual brand combustible cigarette, or smoking cessation. 2. Compare changes in selected physiological endpoints affected by tobacco exposure among cohorts following a forced-switch to exclusive use of a blu e cigarette, dual use of a blu e-cigarette and the subject's usual brand combustible cigarette, or smoking cessation. 3. Determine daily nicotine consumption from blu e-cigarettes following exclusive use of blu e cigarettes or dual use of blu e-cigarettes and the subject's usual brand combustible cigarette over a 5-day period. 4. Assess the effectiveness of exclusive use of blu e-cigarettes or dual use of blu e-cigarettes and the subject's usual brand combustible cigarette to reduce the urge to smoke. 5. Assess subject opinions of various characteristics of blu e-cigarettes. 6. Asse