Nicotine delivery to users from cigarettes and from different types of e-cigarettes
Hajek P., Przulj D., Phillips A., Anderson R., McRobbie H.
Background: 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. Methods: 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. Results: Eleven smokers provided usable data. None of the EC matched cigarettes in nicotine delivery (Cmax = 17.9 ng/ml, Tmax = 4 min and AUC0–>30 = 315 ng/ml/min). The EC with 48 mg/ml nicotine generated the closest PK profile (Cmax = 13.6 ng/ml, Tmax = 4 min, AUC0–>30 = 245 ng/ml/min), followed by a third generation EC using 20 mg/ml nicotine (Cmax = 11.9 ng/ml, Tmax = 6 min, AUC0–>30 = 232 ng/ml/min), followed by the tank system using 20 mg/ml nicotine (Cmax = 9.9 ng/ml, Tmax = 6 min, AUC0–>30 = 201 ng/ml/min). Cig-a-like PK values were similar, ranging from Cmax 7.5 to 9.7 ng/ml, Tmax 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. Conclusions: 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.