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HLT 214 - Substance Use and Abuse - Textbook

Chapter 11. Nicotine

Learning Objectives

At the conclusion of this chapter, students will be able to:

  1. Discuss the history of tobacco use in the US. 
  2. List types of tobacco products and nicotine delivery devices. 
  3. Describe tobacco use prevalence.
  4. Describe the physiological & psychological effects of nicotine. 
  5. Describe the effects of addiction on individuals. 
  6. Define the key features of nicotine dependence

Overview

Humans have used tobacco products for thousands of years. Tobacco cultivation likely began with the development of agriculture in Central Mexico thousands of years ago. It was originally used by Native Americans in religious ceremonies and for medical purposes. Early in tobacco’s history, it was used as a cure-all remedy, for dressing wounds, reducing pain, and even for tooth aches. In the late 15th century, Christopher Columbus was given tobacco as a gift from the Native Americans. The arrival of Spain introduced tobacco to Europe which gained rapid popularity, for it became a lucrative, heavily traded commodity to support the popular habit of smoking. By the early 17th century, scientists were discovering the consequences that smoking tobacco had on people’s lives, including difficulty with breathing and trouble with quitting.

It wasn’t until the 1900’s that cigarettes were made and sold as a major tobacco product in the U.S. Before this, tobacco was used primarily in pipes and cigars, by chewing, and in snuff. In 1901, 3.5 billion cigarettes were sold in the U.S. and more and more tobacco companies were established, creating an entire industry that gained a lot of power. In 1964, the Surgeon General’s report on smoking tobacco was released, shining light on the serious health effects cigarettes were causing. This report also allowed the government to initiate the regulation of the production and sales of cigarettes. In 1985, less than a century after cigarettes became popular, lung cancer became the number one cause of death in women. Rates for lung cancer were even higher than breast cancer at this time. In 1988, Congress prohibited smoking on domestic commercial airline flights scheduled for 2 hours or less. By 1990, the ban was extended to all commercial U.S. flights. On March 21, 2000, the U.S. Supreme Court ruled that the FDA lacks jurisdiction under the Federal Food, Drug, and Cosmetic Act to regulate tobacco products. As a result, the FDA’s proposed rule to reduce access and appeal of tobacco products for young people could not materialize. 1-3

Use and abuse of Tobacco Products

The most common tobacco products, cigarettes are made from leaves of Nicotiana tabacum, which is cured and usually smoked . Nicotine is an alkaloid compound substance and has several natural sources, including tobacco plants, tomatoes, potatoes, eggplant and green peppers. Nicotine as a highly addictive substance has only one natural source—tobacco plant.

There are approximately 50 million people in America who are addicted to some type of tobacco product. Major commercial tobacco products include cigarettes, cigars, snuff, chewing tobacco, and pipe tobacco. Research has shown that nicotine may not be the only ingredient in tobacco that affects its addictive potential. Smoking is linked with a marked decrease in the levels of monoamine oxidase (MAO), an important enzyme that is responsible for the breakdown of dopamine, as well as a reduction in MAO binding sites in the brain. This change is likely caused by some other chemical compound in tobacco smoke other than nicotine. Animal research indicates that acetaldehyde, another chemical in tobacco smoke created by the burning of sugars added as sweeteners, dramatically increases the reinforcing properties of nicotine and may also contribute to tobacco addiction.

Electronic cigarettes—or e-cigarettes—are also called vapes, e-hookahs, vape pens, tank systems, mods, and electronic nicotine delivery systems (ENDS). Using an e-cigarette is commonly called vaping. E-cigarettes work by heating a liquid to produce an aerosol that users inhale into their lungs. The liquid can contain nicotine, tetrahydrocannabinol (THC) and cannabinoid (CBD) oils, and other substances, flavorings, and additives. THC is the psychoactive mind-altering compound of marijuana that produces the “high.”

E-cigarettes have the potential to benefit adult smokers who are not pregnant if used as a complete substitute for regular cigarettes and other smoked tobacco products. E-cigarettes are not safe for youth, young adults, pregnant women, as well as adults who do not currently use tobacco products. While e-cigarettes have the potential to benefit some people and harm others, scientists still have a lot to learn about whether e-cigarettes are effective in helping adults quit smoking. E-cigarette, or vaping, products (nicotine- or THC-containing) should never be used by youths, young adults, or women who are pregnant. Recently an outbreak of Lung Injury Associated with the Use of E-Cigarette, or Vaping, Products, has been reported. CDC, the U.S. Food and Drug Administration (FDA), state and local health departments, and other clinical and public health partners are investigating a national outbreak of e-cigarette, or vaping, product use-associated lung injury (EVALI). As of February 18, 2020, a total of 2,807 hospitalized e-cigarette, or vaping, product use-associated lung injury (EVALI) cases or deaths have been reported to CDC from 50 states, the District of Columbia, and two U.S. territories (Puerto Rico and U.S. Virgin Islands). Persons who never smoked or used other tobacco products or e-cigarettes are strongly advised not to start using any tobacco product.4-6

Pharmacokinetics

Nicotine is readily absorbed from all over the body, including lungs (smoked); mucosa (cigar, chewing tobacco, gum, nasal spray); skin (patch); and gastrointestinal tract (uncommon).

Absorption

  • The most common way to get nicotine into your bloodstream is through inhalation 
  • Your lungs are lined by millions of alveoli, which are the tiny air sacs where gas exchange occurs 
  • These alveoli provide an enormous surface area, 90 times greater than that of your skin, and thus provide ample access for nicotine and other compounds 
  • Nicotine taken in by cigarette or cigar smoking takes only 10-15 seconds to reach the brain but has a direct effect on the body for only ~30 minutes 
  • Nicotine in smoke peaks in brain very rapidly, despite relatively slow increase in blood concentration 
  • A typical cigarette contains 20 mg of nicotine 
  • ~2.5 mg of nicotine is absorbed 
  • Half-life: ~ 2 hours 
  • 80-90% metabolized in liver 

Metabolism and Elimination

  • About 80 percent of nicotine is broken down to cotinine by enzymes in your liver
  • Nicotine is also metabolized in your lungs to cotinine and nicotine-N-oxide
  • Cotinine and the remaining nicotine is filtered from the blood by your kidneys and excreted in the urine

Pharmacodynamics

A chemical in cigarette smoke seems to slow the breakdown of dopamine by affecting MAO levels. Nicotine is a direct agonist for nicotinic ACh receptors. Nicotine initially causes a rapid release of adrenaline, the "fight-or-flight" hormone. Nicotinic ACh receptors are found in the limbic system (e.g. striatum, hippocampus, accumbens), midbrain (e.g. VTA, substantia nigra), various cortical areas (frontal lobe). Nicotine also increases release of various neurohormones and has powerful effects on peripheral nervous system, heart, and other organs.

Acute Effects

  • Classic stimulant effects of arousal (e.g. increased heart rate and blood pressure, alertness, appetite suppression)
  • Carbon monoxide (in smoked form) reduces oxygen transport to heart and other organs
  • Vasoconstriction
  • Can have calming (anxiolytic) effects in some individuals
  • Mild euphoria (relief?)
  • Cognitive enhancements
  • Antidepressant effects

Chronic Effects

  • Smoking leads to disease and disability and harms nearly every organ of the body.
  • More than 16 million Americans are living with a disease caused by smoking.
  • For every person who dies because of smoking, at least 30 people live with a serious smoking- related illness.
  • Smoking causes cancer, heart disease, stroke, lung diseases, diabetes, and chronic obstructive pulmonary disease (COPD), which includes emphysema and chronic bronchitis.
  • Smoking also increases risk for tuberculosis, certain eye diseases, and problems of the immune system, including rheumatoid arthritis.
  • Smoking is a known cause of erectile dysfunction in males.
  • Smoking is the leading cause of preventable death.
  • Worldwide, tobacco use causes more than 7 million deaths per year.
  • Cigarette smoking is responsible for more than 480,000 deaths per year in the United States, including more than 41,000 deaths resulting from secondhand smoke exposure. This is about one in five deaths annually, or 1,300 deaths every day.

Addiction to Tobacco Products

Dependence is a maladaptive pattern of substance use, leading to clinically significant impairment or distress, as manifested by three (or more) of the following, occurring at any time in the same 12-month period:

  1. Tolerance, as defined by either
    • a need for markedly increased amounts of the substance to achieve the desired effect, or
    • markedly diminished effect with continued use of the same amount of substance.
  2. Withdrawal, as manifested by either
    • the characteristic withdrawal syndrome for the substance, or
    • the substance being taken to relieve or avoid withdrawal symptoms.
  3. Taking larger amounts of the substance or over a longer period than was intended.
  4. A persistent desire for or unsuccessful efforts to cut down on substance use.
  5. A great deal of time being spent in activities necessary to obtain or use a substance.
  6. Abandonment or reduction of important social, occupational, or recreational activities because of substance abuse.

People addicted to tobacco products have a physical desire to continue using tobacco, but they also have a psychological desire because of memories associated with using. These memories trigger the urge to use tobacco. Triggers can be anything from music to certain people or places. There is also a strong behavioral addiction associated with nicotine addiction. Most people with an addiction to nicotine are aware of the harm tobacco causes, yet they continue to use the substance. This abusive behavior is characteristic of addiction. No matter how long a person has been addicted to tobacco, quitting is absolutely possible and has tangible health and financial benefits.5-8

 

Chapter Review and Discussion Questions

  1. Explain why cigarette smoking really addictive?
  2. Is there a safe way to smoke? Discuss.
  3. What are the short- and long-term effects of smoking cigarettes?
  4. How do smokers successfully quit?
  5. What are the dangers of exposure to environmental tobacco smoke, or passive smoking (second-hand smoke, third-hand smoke)?