"We believe that this study is a major step forward in understanding how addictive nicotine is delivered by tobacco smoke," said James F. Pankow, Ph.D., professor of environmental and biomolecular systems at OHSU's OGI School of Science & Engineering in Hillsboro, Ore., and a member of the OHSU Cancer Institute. "We found big differences in the percentages of free-base nicotine among 11 commercial cigarette brands."
Nicotine enters a smoker's body mostly carried on the billions of particles in cigarette smoke, Pankow said. In common with street drugs like cocaine, he said, nicotine's molecular structure can appear in both free-base ("unprotonated") and non-free-base ("monoprotonated") forms. The difference is that the free-base form is missing a hydrogen ion, and this allows it to vaporize easily into a gas during smoking. "During smoking, only the free-base form can volatize from a particle into the air in the respiratory tract. Gaseous nicotine is known to deposit super-quickly in the lungs. From there, it's transported rapidly to the brain.
"Since scientists have shown that a drug becomes more addictive when it is delivered to the brain more rapidly," Pankow continued, "free-base nicotine levels in cigarette smoke thus are at the heart of the controversy regarding the tobacco industry's use of additives like ammonia and urea, as well as blending choice
Contact: Mike MacRae
Oregon Health & Science University