PORTLAND, Ore. -- When it comes to nicotine content, all cigarettes are not created equal, according to a new study by researchers at Oregon Health & Science University. In fact, the study finds that some commercial cigarette brands contain 10 to 20 times higher percentages of nicotine in the so-called "free-base" form -- the form thought to be most addictive -- than believed up to now. The study, published today in the online edition of the American Chemical Society's journal Chemical Research in Toxicology, documents the first reliable measurements of free-base nicotine in tobacco smoke.

"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
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Contact: Mike MacRae
macraem@ohsu.edu
503-748-1042
Oregon Health & Science University
24-Jul-2003

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