Nicotine

Despite definitive proof that smoking can be fatal, nicotine still is one of the most widely abused substances. In fact, tobacco kills more than 440,000 U.S. citizens each year — more than alcohol, cocaine, heroin, homicide, suicide, car accidents, and HIV combined.

Tobacco use is the leading preventable cause of death in the United States. The overall cost of smoking in the U.S. is estimated to be $193 billion each year. Nicotine, the addicting substance in tobacco, acts through the well-known acetylcholine nicotinic receptor. This drug can act as both a stimulant and a sedative. Nicotine stimulates the adrenal glands, and the resulting discharge of epinephrine causes a “kick” — a sudden release of glucose paired with an increase in blood pressure, respiration, and heart rate. In addition, nicotine releases dopamine in the brain regions that control motivation, which is one reason that people continue to smoke.

Much better understanding of addiction, coupled with the identification of nicotine as an addictive drug, has been instrumental in the development of treatments. Nicotine gum, the transdermal patch, nasal spray, and inhalers are equally effective in treating the more than one million people addicted to nicotine. These techniques are used to relieve withdrawal symptoms and are helpful in that they produce less severe physiological alterations than using tobacco products. They generally provide users with lower overall nicotine levels than they receive with tobacco and totally eliminate exposure to smoke and its deadly contents.

The first non-nicotine prescription drug, bupropion, an antidepressant, has been approved for use as a pharmacological treatment for nicotine addiction. An exciting advance is the use of varenicline for smoking cessation. This medication interacts directly with the acetylcholine nicotinic receptor in a key part of the brain’s reward circuitry and prevents nicotine from activating this circuit. The development of varenicline is a prime example of how basic science research can lead to the production of novel medications. Behavioral treatments also are important in helping an individual learn coping skills for both short- and long-term prevention of relapse.