Table 1

Nicotine exposure in inexperienced e-cigarette users

Reference	Study characteristics				Results
Reference	Study product	Labelled nicotine content	Sample size	Use duration	Biomarkers of exposure	Relevant comparisons	Other physiological measures
Bullen et al17	Ruyan V8	16 mg	8	e-cigarette: 5 min; inhaler: 10 min; cigarette: 5 min	plasma nicotine (venous): Cmax 1.3 ng/mL, Tmax 19.6 min	Nicorette inhaler (10 mg nicotine): Cmax 2.1 ng/mL, Tmax 32 min; own brand cigarette: Cmax 13.4 ng/mL; Tmax 14.3 min
Eissenberg19	NJOY or Crown 7	16 mg	16	2 bouts of 10 puffs, 30 s interpuff interval, 1 hr between bouts	plasma nicotine: after 5 min, 2.5 ng/mL (NJOY), 3.5 ng/mL (Crown 7)	own brand cigarette: 16.8 ng/mL	no increases in HR
Vansickel et al20	NJOY or Crown 7	18 mg, 16 mg	32	2 bouts of 10 puffs, 30 s interpuff interval, 1 h between bouts	no significant changes to plasma nicotine	own brand cigarette: within 5 min, 2.1–18.8 ng/mL	no increases in HR
Vansickel et al21	Vapor King	18 mg/mL	20	6 bouts of 10 puffs, 20 s interpuff interval, 30 min between bouts	plasma nicotine: 5 min after final bout, 2.2–7.4 ng/mL		5 min after first bout, HR increased from 67.5 to 75 bpm
Flouris et al22	Giant	11 mg/mL	15	Equivalent puffs to approximate nicotine delivery with two own brand cigarettes, based on 1.5 cigarette/e-cigarette nicotine absorption ratio	serum cotinine: significant increases immediately following and 1 h after use	2 own brand cigarettes: no difference between e-cigarette and cigarette use

HR, heart rate; bpm, beats per minute; Cmax, maximum drug concentration; Tmax, time at which maximum drug concentration is observed.