Burning tobacco produces smoke that contains nicotine and more than 4000 other carcinogenic and toxic compounds that result from volatilization, pyrolysis, and pyrosynthesis of tobacco and other additives in tobacco products. The smoke is composed of a vapor phase and a fine aerosol where the particles are of a size that results in their deposition in both the airways, and more importantly, the huge surface of the capillary alveolar interface in the lungs. Nicotine is rapidly absorbed through the lungs and into the blood and reaches the brain within 8 to 20 seconds. Absorption in the lungs avoidance first pass metabolism and arterial levels exceed venous levels by 10 fold. Tobacco smoke has in an acidic pH which markedly reduces absorption of nicotine in the mouth. This requires inhalation of smoke deep into the lungs where there’s a more basic pH that facilitates the absorption of nicotine. The blends of tobacco used to for pipes and cigars have a higher pH which is sufficient to facilitate absorption of nicotine across the oral mucosa.
-
-
It is the rapid and greater increase in plasma nicotine levels produced by smoking that relate to its addictive potential since other forms of non-tobacco nicotine delivery that produce a smaller and slower rise in blood and brain nicotine have not been reported to be addictive.
Smoking Increases Plasma Nicotine Much More Rapidly than Other Routs of Nicotine Administration
The Rapid Increase in Plasma Nicotine after Smoking a Cigarette Increases Liking and Addiction PotentialWithin 20 seconds after smoking a cigarette arterial nicotine levels are 10 times higher than venous levels, and the rapid increase in plasma nicotine produces the “high” from cigarette smoking. Similar to smoked or intravenous cocaine which produces a rapid “high”, smoking tobacco produces a rapid increase in plasma nicotine which is liked by the smoker and leads to addiction. There is little addictive abuse of over the counter nicotine replacement medications, which produce a slow increase in plasma nicotine.(Constructed from data in Fant, R.V. et al. Primary Care, 26: 633 - 652, 1999; Henningfield, J.E. et al. Engl J Med, 333: 1196 – 1203, 1995; and other sources) ©2011 NBEP
