title: The comparative efficacy of first- versus second-generation electronic cigarettes in reducing symptoms of nicotine withdrawal.
abstract: OBJECTIVE
  Currently, electronic cigarettes (e-cigarettes) are studied as though they are a homogeneous category. However, there are several noteworthy differences in the products that fall under this name, including potential differences in the efficacy of these products as smoking cessation aids. The current study examined the comparative efficacy of first- and second-generation e-cigarettes in reducing nicotine withdrawal symptoms in a sample of current smokers with little or no experience of using e-cigarettes.
  
  
  METHODS
  Twenty-two mildly to moderately nicotine-dependent individuals were randomized to a cross-over design in which they used first- and second-generation e-cigarettes on separate days with assessment of withdrawal symptoms directly prior to and after product use.
  
  
  METHODS
  A community-based sample recruited in the Midwest region of the United States reported a mean age of 28.6 [standard deviation (SD) = 12.9]. The majority were male (56.5%), Caucasian (91.3%), reported smoking an average of 15.2 (SD = 9.6) tobacco cigarettes per day, and a mean baseline carbon monoxide (CO) level of 18.7 parts per million (p.p.m.).
  
  
  METHODS
  Symptoms of withdrawal from nicotine were measured via the Mood and Physical Symptoms Scale.
  
  
  RESULTS
  Analysis of changes in withdrawal symptoms revealed a significant time × product interaction F(1, 21)  = 5.057, P = 0.036, n(2) P  = 0.202. Participants experienced a larger reduction in symptoms of nicotine withdrawal after using second-generation compared with first-generation e-cigarettes.
  
  
  CONCLUSIONS
  Second-generation e-cigarettes seem to be more effective in reducing symptoms of nicotine withdrawal than do first-generation e-cigarettes.
authors: Oklahoma State University, Stillwater, OK, USA.
authors: William V
authors: WV
authors: Lechner
authors: Ellen
authors: E
authors: Meier
authors: Josh L
authors: JL
authors: Wiener
authors: DeMond M
authors: DM
authors: Grant
authors: Jenna
authors: J
authors: Gilmore
authors: Matt R
authors: MR
authors: Judah
authors: Adam C
authors: AC
authors: Mills
authors: Theodore L
authors: TL
authors: Wagener
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D018592:Cross-Over Studies; D066300:Electronic Nicotine Delivery Systems / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D009538:Nicotine / Q000009:adverse effects*; D016540:Smoking Cessation / Q000379:methods* / Q000706:statistics & numerical data; D013375:Substance Withdrawal Syndrome / Q000517:prevention & control*; D014029:Tobacco Use Disorder / Q000628:therapy*; D016896:Treatment Outcome
chemical_list: D009538:Nicotine
keywords: Comparative efficacy; electronic cigarettes; ends; nicotine; smoking; withdrawal symptoms