title: Nicotine concentrations with electronic cigarette use: effects of sex and flavor.
abstract: BACKGROUND
  This study examined overall changes in nicotine concentrations when using a popular e-cigarette and 18 mg/mL nicotine e-Juice, and it further explored effects of sex and flavorings on these concentrations.
  
  
  METHODS
  We recruited nontreatment-seeking smokers who were willing to try e-cigarettes for 2 weeks and abstain from cigarette smoking. Subjects were randomized to either menthol tobacco or non-menthol tobacco-flavored e-cigarette use for 7-10 days, and the next week they were crossed over to the other condition. On the last day of e-cigarette use of each flavor, subjects completed a laboratory session in which they used the e-cigarette for 5 min ad libitum. Nicotine concentrations were obtained 5 min before and 5, 10, 15, 20, and 30 min after the onset of e-cigarette use.
  
  
  RESULTS
  Twenty subjects completed at least 1 monitoring session. Nicotine concentrations significantly increased from baseline to 5 min by 4 ng/mL at the first laboratory session (p < .01) and by 5.1 ng/mL at the second laboratory session (p < .01). Combining sessions, there were no main effects of sex or preferred flavor (based on smoking history) on changes in nicotine concentrations. After adding preferred flavor, sex, and visit order to the model, there was a significant preferred flavor by sex interaction (p < .01), such that women who received nonpreferred flavors had lower nicotine concentrations and rated their e-cigarette as less likeable (p < .01).
  
  
  CONCLUSIONS
  We found nicotine concentrations significantly increase after e-cigarette use for 5 min, and flavor may impact nicotine concentrations with e-cigarette use in women.
authors.affiliation: Department of Medicine and Obstetrics and Gynecology, University of Connecticut Health Center, Farmington, CT; oncken@nso2.uchc.edu.
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Oncken
authors.affiliation: Department of Oral Health and Diagnostic Sciences and Department of Psychiatry, University of Connecticut Health Center, Farmington, CT;
authors.forename: Mark D
authors.initials: MD
authors.lastname: Litt
authors.affiliation: Department of Medicine, University of Connecticut Health Center, Farmington, CT.
authors.forename: Lynn D
authors.initials: LD
authors.lastname: McLaughlin
authors.affiliation: Department of Medicine, University of Connecticut Health Center, Farmington, CT.
authors.forename: Nausherwan A
authors.initials: NA
authors.lastname: Burki
mesh_terms: D000293:Adolescent; D000328:Adult; D066300:Electronic Nicotine Delivery Systems; D005260:Female; D005421:Flavoring Agents / Q000008:administration & dosage*; D005783:Gender Identity; D006801:Humans; D008297:Male; D008875:Middle Aged; D009538:Nicotine / Q000008:administration & dosage*
chemical_list: D005421:Flavoring Agents; D009538:Nicotine