Nicotine, the most well-known of all tobacco compounds, is highly addictive. A number of factors influence the effects nicotine can have on you, including how much nicotine you inhale or absorb, how quickly you absorb it, how much tolerance you develop and how quickly your body metabolizes the drug.
About Nicotine
Nicotine is the principal tobacco alkaloid, a natural ingredient found in tobacco leaves, where it acts as a potent insecticide. It comes in many forms: Cigarettes, oral snuff and pipe tobacco contain similar concentrations, while cigar and chewing tobacco contain about one-half as much nicotine as cigarettes. When you smoke, you absorb nicotine in your lungs. When you chew tobacco, you absorb nicotine through your oral mucous membranes. You may also absorb nicotine through your skin.
Nicotine Absorption
When you inhale smoke from a cigarette, the nicotine is distilled from the tobacco and carried into the lungs in smoke particles. Nicotine is rapidly absorbed into the veins of the lungs, where it enters the arteries and is quickly transported to the brain. Once in the brain, nicotine stimulates pleasure centers, and it is this pleasurable effect that eventually causes addiction as you begin to crave the effect of tobacco.
Nicotine and Metabolism
A number of factors can affect how you metabolize nicotine. Nicotine levels decline in the body after a meal. Menthol, widely used in mouthwash, foods and toothpaste, inhibits nicotine metabolism. Older people do not metabolize nicotine as well as younger people. Women tend to metabolize nicotine more quickly than men, especially women who use oral contraceptives or who are pregnant.
Nicotine Clearance
Individual differences in metabolism can also affect how quickly your body excretes nicotine. Nicotine clearance -- the rate at which your body removes nicotine -- is variable; genetic, racial and hormonal factors determine the variability. N.L. Benowitz reported in the April 2008 "Clinical Pharmacology & Therapeutics" that genetically poor metabolizers smoke fewer cigarettes per day and have higher carbon monoxide levels than do normal metabolizers.
Metabolism and Quitting
Metabolizing nicotine more slowly is an advantage if you are trying to quit, as the rate at which nicotine clears from your body influences your smoking behavior. As nicotine clears from the body, withdrawal symptoms appear, and the urge to smoke another cigarette becomes stronger. One study of adolescent smokers published in the September 2008 issue of "Pediatrics" showed that faster metabolizers reported greater withdrawal symptoms than slow metabolizers.
Further Considerations
Nicotine has a number of negative effects on the human body, and it would be better not to start smoking. If you are a smoker and want to quit, you may need the help of a health care professional.
References
- "Pharmacological Reviews"; Metabolism and Disposition Kinetics of Nicotine; J. Hukkanen, et al.; March 2005
- "Clinical Pharmacology & Therapeutics"; Clinical Pharmacology of Nicotine: Implications for Understanding, Preventing, and Treating Tobacco Addiction; N.L. Benowitz; April 2008
- "Pediatrics"; Rate of Nicotine Metabolism and Withdrawal Symptoms in Adolescent Light Smokers; M.L. Rubenstein, et al.; September 2008
- "Annual Review of Pharmacology and Toxicology"; Pharmacology of Nicotine: Addiction, Smoking-induced Disease, and Therapeutics; Neal L. Benowitz; 2009
