Nicotine delivery to users from cigarettes and from different types of e-cigarettes

Peter Hajek, Dunja Przulj, Anna Phillips, Rebecca Anderson, Hayden McRobbie

Delivering nicotine in the way smokers seek is likely to be the key factor in e-cigarette (EC) success in replacing cigarettes. We examined to what degree different types of EC mimic nicotine intake from cigarettes. Twelve participants ('dual users' of EC and cigarettes) used their own brand cigarette and nine different EC brands. Blood samples were taken at baseline and at 2-min intervals for 10 min and again at 30 min. Eleven smokers provided usable data. None of the EC matched cigarettes in nicotine delivery (C max = 17.9 ng/ml, T max = 4 min and AUC0->30 = 315 ng/ml/min). The EC with 48 mg/ml nicotine generated the closest PK profile (C max = 13.6 ng/ml, T max = 4 min, AUC0->30 = 245 ng/ml/min), followed by a third generation EC using 20 mg/ml nicotine (C max = 11.9 ng/ml, T max = 6 min, AUC0->30 = 232 ng/ml/min), followed by the tank system using 20 mg/ml nicotine (C max = 9.9 ng/ml, T max = 6 min, AUC0->30 = 201 ng/ml/min). Cig-a-like PK values were similar, ranging from C max 7.5 to 9.7 ng/ml, T max 4-6 min, and AUC0->30 144 to 173 ng/ml/min. Moderate differences in e-liquid nicotine concentrations had little effect on nicotine delivery, e.g. the EC with 24 mg/ml cartridge had the same PK profile as ECs with 16 mg/ml cartridges. Using similar strength e-liquid, the tank EC provided significantly more nicotine than cig-a-like ECs. EC brands we tested do not deliver nicotine as efficiently as cigarettes, but newer EC products deliver nicotine more efficiently than cig-a-like brands. Moderate variations in nicotine content of e-liquid have little effect on nicotine delivery. Smokers who are finding cig-a-like EC unsatisfactory should be advised to try more advanced systems.