title: Nicotine Replacement, Topography, and Smoking Phenotypes of E-cigarettes.
abstract: OBJECTIVE
  Little is known about the degree of nicotine replacement across first-generation e-cigarette brands, how e-cigarettes are used, and if there is variation across brands in relevant smoking phenotypes. The objective of this project was to collect data that are critical to better understanding, use, and exposure when using e-cigarettes, which may then inform clinical trials and tobacco regulatory policy.
  
  
  METHODS
  Twenty-eight cigarette smokers were randomized to use one of 5 popular brands of e-cigarettes for a 10-day study. Day 1 (own cigarette brand) data established baseline levels for cotinine, carbon monoxide (CO), topography, cigarette liking, withdrawal, and craving. Participants returned on Days 5 and 10 to reassess these measures while exclusively using e-cigarettes.
  
  
  RESULTS
  Compared to cigarette smoking, e-cigarettes provided significantly lower nicotine levels (25%-50%), reduced CO exposure, and lower ratings of liking (p < .05). Topography significantly differed between cigarette and e-cigarette sessions (p < .05). All brands significantly reduced withdrawal and craving (p < .05). There were no significant brand differences in outcome measures associated with exposure or use.
  
  
  CONCLUSIONS
  E-cigarettes are not liked as much as cigarettes, provide significantly lower nicotine replacement, reduce CO exposure, and mitigate withdrawal and craving. The patterns of use significantly differ compared to cigarette smoking.
authors.affiliation: Department of Psychiatry, University of Pennsylvania, Philadelphia, PA.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Strasser
authors.affiliation: Department of Psychiatry, University of Pennsylvania, Philadelphia, PA.
authors.forename: Valentina
authors.initials: V
authors.lastname: Souprountchouk
authors.affiliation: Department of Psychiatry, University of Pennsylvania, Philadelphia, PA.
authors.forename: Amanda
authors.initials: A
authors.lastname: Kaufmann
authors.affiliation: Department of Psychiatry, University of Pennsylvania, Philadelphia, PA.
authors.forename: Sonja
authors.initials: S
authors.lastname: Blazekovic
authors.affiliation: Pulmonary, Allergy, & Critical Care Division, University of Pennsylvania Presbyterian Medical Center, Philadelphia, PA.
authors.forename: Frank
authors.initials: F
authors.lastname: Leone
authors.affiliation: Division of Clinical Pharmacology and Experimental Therapeutics, Departments of Medicine and Bioengineering & Therapeutic Sciences, University of California-San Francisco, San Francisco, CA.
authors.forename: Neal L
authors.initials: NL
authors.lastname: Benowitz
authors.affiliation: Department of Psychiatry, University of Pennsylvania, Philadelphia, PA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Schnoll
keywords: cotinine; e-cigarette; nicotine craving; nicotine withdrawal; smoking behavior; vaping