Nicotine addiction review

June 19, 2010, 6:15 pm

★★★☆☆

Nicotine Addiction. Benowitz NL N Engl J Med June 17, 2010;362:2295-2303.

No abstract available

This review of nicotine addiction points out that while 70% of smokers claim they would like to quit, only 3% actually do give up smoking each year.  To understand why this rate is so low, it is important to consider what exactly the drug does in the body.  Nicotine binds to specific cholinergic receptors, opening sodium and calcium channels. This allows increased amounts of calcium to enter neurons in areas of the central nervous system, releasing neurotransmitters such as dopamine that increase sensations of pleasure and reinforce the urge to administer the drug repeatedly.

Other components of cigarette smoke also contribute to this effect.  For example, products of acetaldehyde combustion inhibit the enzyme monoamine oxidase (MAO), decreasing the rate at which dopamine is metabolized.

Nicotine both induces pleasure through its effect on dopamine, and decreases stress and anxiety.  Symptoms of nicotine withdrawal include irritability, restlessness, anxiety, and depression.  Nicotine addiction is fueled  by the effects of the drug itself, the desire to avoid withdrawal symptoms, and conditioning in certain situations (e.g., after meals or at a bar).

Nicotine is converted to the much less active metabolite cotinine by the hepatic enzyme CYP2A6. The rate at which this occurs varies from individual to individual, with females as a group more likely to be rapid metabolizers and thus have more difficulty in quitting the habit.

To see how nicotine works, click here.

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