title: Monitoring nicotine intake from e-cigarettes: measurement of parent drug and metabolites in oral fluid and plasma.
abstract: BACKGROUND
  Electronic cigarettes (e-cig) known as electronic nicotine devices recently gained popularity among smokers. Despite many studies investigating their safety and toxicity, few examined the delivery of e-cig-derived nicotine and its metabolites in alternative biological fluids.
  
  
  METHODS
  We performed a randomized, crossover, and controlled clinical trial in nine healthy smokers. Nicotine (NIC), cotinine (COT), and trans-3'-hydroxycotinine (3-HCOT) were measured in plasma and oral fluid by liquid chromatography-tandem mass spectrometry after consumption of two consecutive e-cig administrations or two consecutive tobacco cigarettes.
  
  
  RESULTS
  NIC and its metabolites were detected both in oral fluid and plasma following both administration conditions. Concentrations in oral fluid resulted various orders of magnitude higher than those observed in plasma. Oral fluid concentration of tobacco cigarette and e-cig-derived NIC peaked at 15 min after each administration and ranged between 1.0 and 1396 μg/L and from 0.3 to 860 μg/L; those of COT between 52.8 and 110 μg/L and from 33.8 to 94.7 μg/L; and those of 3-HCOT between 12.4 and 23.5 μg/L and from 8.5 to 24.4 μg/L. The oral fluid to plasma concentration ratio of both e-cig- and tobacco cigarette-derived NIC peaked at 15 min after both administrations and correlated with oral fluid NIC concentration.
  
  
  CONCLUSIONS
  The obtained results support the measurement of NIC and metabolites in oral fluid in the assessment of intake after e-cig use and appear to be a suitable alternative to plasma when monitoring nicotine delivery from e-cig for clinical and toxicological studies.
authors: Esther
authors: E
authors: Papaseit
authors: Magí
authors: M
authors: Farré
authors: Silvia
authors: S
authors: Graziano
authors: Roberta
authors: R
authors: Pacifici
authors: Clara
authors: C
authors: Pérez-Mañá
authors: Oscar
authors: O
authors: García-Algar
authors: Simona
authors: S
authors: Pichini
mesh_terms: D015415:Biomarkers / Q000032:analysis*; D002853:Chromatography, Liquid; D018592:Cross-Over Studies; D066300:Electronic Nicotine Delivery Systems; D006801:Humans; D009538:Nicotine / Q000008:administration & dosage / Q000032:analysis* / Q000378:metabolism*; D010949:Plasma / Q000737:chemistry*; D012463:Saliva / Q000737:chemistry*; D053719:Tandem Mass Spectrometry
chemical_list: D015415:Biomarkers; D009538:Nicotine