Regional deposition of inhaled 11C-nicotine vapor in the human airway as visualized by positron emission tomography.
The deposition of 11C-nicotine in the respiratory tract from a nicotine vapor inhaler was studied by means of positron emission tomography (PET) in an intrasubject comparison of six healthy smokers using two modes of inhalation: one with shallow, frequent inhalations ("buccal mode") and one with deep inhalations ("pulmonary mode"). An average of 15% of the radioactivity was released from the vapor inhaler after 5 minutes of inhalation. Approximately 45% of the dose released was found in the oral cavity. A significant amount of radioactivity, 10%, was observed in the esophagus, suggesting transfer of a major fraction of the dose to the stomach. Only a minor fraction, 5%, was found in the lungs, followed by 2% in the bronchi and 1% in the trachea. The deposition in the oral cavity closely followed a linear pattern during the 5 minutes of inhalation and was followed by a rapid elimination from the oral cavity, with an average half-life of 18 minutes. Only 8% of the dose released remained in the oral cavity 45 minutes after the end of inhalation. On the other hand, the dose fraction of about 14% distributed into the body tissue compartment at the end of inhalation had risen to 60% at that late time point. No statistically or clinically important differences were observed between the buccal and the pulmonary mode of inhalation in either deposition pattern or elimination rates.
Bergström
M
M
Uppsala University PET Center, UAS, Sweden.
Nordberg
A
A
Lunell
E
E
Antoni
G
G
Långström
B
B
D000280:Administration, Inhalation; D000328:Adult; D002250:Carbon Radioisotopes; D006801:Humans; D008297:Male; D008875:Middle Aged; D009055:Mouth / Q000000981:diagnostic imaging*; D009330:Nebulizers and Vaporizers; D009538:Nicotine / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D012137:Respiratory System / Q000000981:diagnostic imaging*; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D009538:Nicotine