Chapter 7 Nicotine

Background Nicotine is found in the tobacco plant Different types of tobacco result from differences in cultivation and processing Tobacco leaves are harvested while still green and undergo curing and fermentation to produce the commercial products – cigarettes, cigars, snuff, chewing tobacco, and pipe tobacco Tobacco has many constituents, but nicotine has the broadest and most immediate pharmacological action

Nicotine is extremely toxic – about as toxic as cyanide – and only 60 milligrams are needed to kill a human When tobacco is burned, the smoke contains a small portion of nicotine, which the body metabolizes to a nontoxic substance Less familiar are the forms of smokeless tobacco which include snuff and chewing tobacco

Snuff is powdered tobacco mixed with salts, moisture, oils, flavorings, and other additives. It is marketed in two forms, dry and moist Chewing tobacco is marketed as a pressed rectangle called a plug, or in a twist or roll. Aroma and flavoring agents are added A quid (piece) of tobacco can be either chewed or held between the cheek and gum (“dipping”)

History of Tobacco Use Columbus and other explorers brought home and spread tobacco to other parts of the world For approximately 350 years after, tobacco was accepted as having medical therapeutic value It was esteemed as a panacea weed and was thus administered in a variety of ways for a variety of conditions (See Table 7.1) Later it came under attack and was blamed for perverted sexuality, impotency, and insanity

Prevalence of Tobacco Use In the United States today, cigarette smoking is by far the most common way to use tobacco It is the most toxic way to smoke tobacco, followed in order by cigar and pipe smoking Studies show the percentage of men and women who smoke declined in the latter part of the 20 th century There is steady increase in the percentage of adults who identify themselves as former smokers

Most of the people who quit smoking did so on their own. Self quitters are thought to have been “lighter” (fewer than 25 cigarettes a day) smokers The peak of smoking among Americans was in 1963, prior to the publishing of the U.S. Public Health Service’s Smoking and Health: Report of the Advisory Committee to the Surgeon General in 1964 It detailed the health hazards of cigarette smoking and a way unprecedented in scope and persuasion

Prevalence Among Subgroups 18-25 year olds have the highest rates of current cigarette use, and have the greatest differences in rates of smoking between men and women (43.5 to 35.5%) Whites have the highest rates among all age groups combined, but blacks have a slightly higher rate among those 26 and older There are more smokers among the unemployed As years of education increase, prevalence of smoking decreases

Initiation of Smoking Among respondents aged 12-17, the 2004 National Household Survey shows an increase (35%) in the rate of cigarette smoking initiation from 1990-95 followed by a decrease (13%) from 1995-2001. Overall, for the period 1990-2001, there was a 14% increase in the rate of smoking initiation Data is similar for the 18-25 year old respondents, though less dramatic

Overall use patterns did not change but survey date for 2000-2004 show a slight reduction in smoking initiation rates attributed to a change in practices of advertising cigarettes Some research suggests that smoking tends to begin in adolescence because teen’s brains are more sensitive to the rewarding (reinforcing) effects of nicotine than are the brains of older individuals

PET scans suggest individuals who score high on personality characteristics such as hostility and aggression are more stimulated by a dose of nicotine and thus may be more likely to begin and continue smoking Adolescents who score high on “novelty seeking” are more receptive to tobacco company advertisements

Pharmacology of Nicotine Nicotine stimulates the same receptors that are sensitive to acetylcholine (ACH) Affects of ACH on biology and behavior include: Increases blood pressure Increases heart rate Stimulates release of adrenaline Increases tone and activity of gastrointestinal tract Facilitates release of dopamine and seratonin Affects CNS functions of arousal, attention, learning, memory storage and retrieval, mood, and rapid eye movement (REM) during sleep

Absorption Nicotine can be absorbed through most of the body’s membranes (Example: Florist hospitalized for nicotine poisoning) Nicotine Poisoning – A consequence of nicotine overdose, characterized by palpitations, dizziness, sweating, nausea, or vomiting Nicotine is most readily absorbed through the lungs, which makes inhaling cigarette smoke an efficient way to get a dose of nicotine

Distribution When a cigarette is inhaled, nicotine reaches the brain from the lungs within 7 seconds. By comparison, it takes 14 seconds for blood to flow from the arm to the brain when a drug is injected intravenously The effects of nicotine can be observed rapidly because its distribution half-life is only 10-20 minutes The speed of absorption and distribution is one reason why smokers reach for a cigarette so soon after they have finished their last one

Metabolism and Excretion The liver is the major organ responsible for metabolizing nicotine The lungs and kidneys also play a part in the chemical breakdown of nicotine Nicotine is eliminated primarily in the urine, with 10-20% eliminated unchanged through the urinary tract Its elimination half-life in a chronic smoker is about two hours The smoker must maintain a nicotine blood level not below the threshold for the beginning of withdrawal symptoms

Tolerance Tolerance develops quickly. For example, first attempts at smoking usually result in palpitations, dizziness, sweating, nausea, or vomiting Tolerance can be seen in the span of one cigarette such as when the effects of nicotine in the initial puffs of the first cigarette of the day are greater than those in the last few puffs Dispositional tolerance develops as smokers metabolize the drug more quickly than nonsmokers

Dependence In 1988 the U.S. Surgeon General’s Office issued a full report with the conclusion that physical dependence on nicotine develops and that the drug is addicting Studies had shown this for some time Common symptoms reported by smokers 24 hours after they stopped smoking included craving for tobacco, followed in order by irritability, anxiety, difficulty concentrating, restlessness, increased appetite, impatience, somatic complaints, and insomnia

Acute Effects of Nicotine Nicotine is called a biphasic drug because at low doses it stimulates ACH receptors but at higher doses it retards neural transmission This partly explains the complex effects that humans perceive when they use it Nicotine’s enhancing effects on alertness, learning, and memory may account for part of its reinforcing effects in humans Stimulation of the heart and its resultant increased demands for oxygen underlie the association of nicotine and heart disease

Though nicotine is classified as a stimulant, people who use it often report decreased arousal in the form of a calming effect. Possible reasons include: Biphasic effect of depressant effects at higher doses Nicotine relaxes the skeletal muscles Smoker’s perception of successfully coping with stress while smoking, along with other beliefs that may influence reactions to smoking Use associated with pleasant social situations such as parties

Many other secondary associated effects that can contribute to the smoker’s perception that the drug has calming effects Nicotine decreases one’s appetite for sweet foods and increases the amount of energy the body uses both while it is resting and exercising. Thus quitting smoking is often associated with weight gain The nicotine-body weight relationship has been attributed to decisions to start smoking, to continue smoking, and to resume smoking after quitting

Effects of Chronic Tobacco Use Chronic or long-term use is associated with life-threatening diseases such as coronary heart disease, cancers of the larynx, oral cavity, esophagus, bladder, pancreas, kidney and lungs, and chronic obstructive lung disease such as emphysema Emphysema – Disease of the lung characterized by abnormal dilution of its air spaces and distension of its walls. Frequently heart action is impaired

More than 430, 000 Americans who smoke die prematurely each year – almost 1,200 people a day At age 45, 6 of 1,000 women smokers are likely to die of a heart attack compared to 2 of 1,000 nonsmokers. The disparity continues with further aging and for all causes of death For men, death by heart attack, stroke, or lung cancer from age 30 to old age also showed significant disparities

In 1995, health care cost to U.S. society for its citizens’ cigarette smoking was $80 billion The three ingredients in tobacco smoke causing damage are nicotine, tar, and carbon monoxide Carbon monoxide deprives the body’s tissues of oxygen. The brain and heart are especially vulnerable to this action as they depend on aerobic respiration for proper functioning

Most of the cancer-causing substances in smoke are in tar, the material that remains after cigarette smoke is passed through a filter Amount of tar and nicotine delivered in U.S. brand name cigarettes has declined considerably from 21.6 and 1.35 in 1968 to 12.0 and 0.88 in 1998 The implication that low-yield nicotine and tar cigarettes are less hazardous is deceptive given that smokers either consciously or unconsciously inhale more intensely or smoke more cigarettes

Legal Action Between the 1950s and 1990s, hundreds of lawsuits were filed against cigarette companies claiming they were responsible for the smokers poor health Until the 1980s, all cases had failed and through the mid-1990s legal action against the tobacco companies was still generally unsuccessful Class action suits have been more successful due to increased resources of groups of people over individuals

Passive Smoking Passive smoking is an active killer You absorb nicotine, carbon monoxide, and other elements of tobacco smoke when in the vicinity of people smoking It has been suggested that passive smoking in household kills about 53,000 Americans a year The fetus is exposed to nicotine if the nonsmoking mother is regularly exposed Children whose parents smoke are more likely to have bronchitis and pneumonia as well as some impaired pulmonary function

Treatment of Cigarette Smoking Smokers say they quit for the following reasons: Fearing getting sick Feeling in control Proving that quitting is possible Stopping others from nagging Being forced by others to quit Saving money They relapse due to withdrawal symptoms, stress and frustration, social pressure, alcohol use, and weight gain

Relapse – A term from physical disease; return to a previous state of illness from one of health. As applied to smoking, it means the smoker resumes smoking after having abstained for some amount of time. Though most people stop smoking without help, formal treatment is generally considered worthwhile due to the fact that the people who did quit smoking only did so after multiple attempts

Necessity of Formal Treatment A 2005 follow-up study showed that 21% of adult smokers who had received intensive smoking cessation therapy 14.5 years earlier sustained their stopped-smoking status compared to only 5% of individuals who had not received the treatment. It seems that if smoking treatments increase the rate of smoking cessation compared to what people do on their own, then they would be more than worth their cost.

Treatment Effectiveness Programs to help people stop smoking focus on: Controlling withdrawal symptoms Breaking habitual motor behavior involved in smoking Learning skills to cope with emotions, thoughts, and situations in which smokers say they use cigarettes to help them Smoking Cessation approaches maybe classified into two main categories: behavioral programs and nicotine replacement therapies

Behavioral programs teach smokers to identify situations that presented a “high risk” for them to smoke, to apply techniques to weaken the habit components of smoking, to teach coping responses in high risk situations, and to teach smokers to self-monitor their smoking behavior Nicotine replacement therapies involve the administration of nicotine to smokers as part of the effort to help them quit. The nicotine comes in the form of gum, patches, nasal spray, and inhaler

Some studies support the hypothesis that women have a more difficult time quitting smoking than men because their smoking is more affected by nonnicotine factors and thus longer-term effectiveness of NRT required more intensive behavioral support. The antidepressant Bupropion (Welbutrin) has been successful in the treatment of nicotine dependence independent of a history of depression. This would explain why other antidepressants such as fluoxetine (Prozac) have not been effective.

Research on nicotine replacement therapies has led to the following conclusions: All replacement therapies raise the chances of quitting smoking by 2 compared to placebo There is no difference in the effectiveness of different therapies Smokers may have initial preferences for one therapy over another, but eventually adapt to the one they are using Combining nicotine replacement therapies with behavioral programs enhances the quit rates that typically are achieved be either treatment alone

Conclusions Informational campaigns on the hazards of smoking have been successful in decreasing the prevalence of smoking and other uses of tobacco in U.S. adults There should be more emphasis on tobacco use prevention for youth and greater restrictions on advertising by tobacco companies Continued expansion of smoking-treatment formats and further exploration of harm reduction approaches is encouraged

The best way to stop people from using nicotine is to continue with the informational campaigns along with “macro-environmental” methods such as banning smoking in public places, new treatments at work sites, and brief behavioral or nicotine replacement treatment delivered in the medical care setting as they have also been credited with reducing the prevalence of smoking and other use of tobacco among U.S. adults.

Chapter 7 Nicotine

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Chapter 7 Nicotine