Site of nicotine absorption from a vapour inhaler--comparison with cigarette smoking.

OBJECTIVE: The aim of the study was to assess the site of nicotine absorption during and after use of a nicotine-vapour inhaler compared with that after cigarette smoking.
METHODS: Using a catheterisation technique, the nicotine plasma concentration-time profiles in arterial and jugular venous blood after using a nicotine inhaler were compared with those achieved after cigarette smoking a in seven healthy habitual smokers.
RESULTS: After use of the inhaler, arterial nicotine concentrations rose slowly to a maximum level of 5. 9 +/- 1.5 ng/ml at a mean time to reach peak concentration (t(max)) of 9.0 +/- 1.1 min, whereas jugular venous nicotine levels peaked at 25.4 +/- 5.4 ng/ml at 6.7 +/- 0.3 min. The concentration-time curves indicate that the absorption occurs mainly via the mucosa of the oral cavity and the pharynx, and that there is minimal absorption via the lungs. In contrast, after smoking a cigarette, arterial nicotine plasma concentrations rose quickly to a maximum level of 49. 2 +/- 9.7 ng/ml after 4.0 +/- 0.6 min, while the maximum concentration of nicotine in the jugular vein was 22.4 +/- 3.9 ng/ml after 6.4 +/- 0.4 min, indicating primarily pulmonary absorption of nicotine.
CONCLUSION: Nicotine absorption after use of the vapour inhaler occurs primarily via the mucosa of the oral cavity; the absorption occurs slowly and the arterial nicotine concentration spike, typical of cigarette smoking, is avoided. Thus, the likelihood for abuse of the nicotine inhaler is probably small.