ABSTRACT
PATTERNS OF TOBACCO USE Tobacco is burnt in cigarettes, pipes and cigars; taken nasally as finely ground 'dry' snuff, and orally as 'wet' snuff and chewing tobacco. The common feature is that all these different products and routes of administration permit the absorption of significant amounts of nicotine into the bloodstream. Absorption through the lungs is particularly efficient. Nicotine reaches the brain within seven seconds of puffing and inhaling the smoke from a cigarette, faster than uptake from intravenous injection. Once absorbed, nicotine is rapidly taken up by the brain and tissues throughout the body. It has an initial distributional half-life in blood of about ten minutes, and a terminal half-life of about two hours. This reflects metabolism to a pharmacologically inert form, cotinine, in the liver, and some excretion of nicotine unchanged in the urine (Benowitz, 1988).
