Nicotine Addiction is a well-known among the teen community. Nicotine dependence can be successfully treated. The drug ‘Nicotine’ is a psychoactive drug with effects that reinforce tobacco use even though known harmful health effects. Family physicians are in an excellent position to promote both smoking cessation and smoking prevention. Nicotine is a psychoactive agent whose continued use usually leads to addiction. The pharmacologic and psychologic processes that determine nicotine addiction are similar to those that determine addiction to other drugs, such as heroin and cocaine. The most common form of nicotine dependence is associated with the inhalation of cigarette smoke. Pipe and cigar smoking, tobacco chewing and the use of snuff are less likely to lead to nicotine dependence. This article, therefore, focuses on cigarette smoking as the primary agent of nicotine addiction.
Cigarette smoking may be responsible for as many as 350,000 deaths annually in the United States, representing 18 percent of all deaths. Total costs of smoking-related health care and lost productivity amount to approximately $65 billion each year.
Despite escalating cigarette consumption worldwide, U.S. smoking rates are declining. Consumption reached a peak in the early 1960s, when 42 percent of adults smoked (52 percent of men and 34 percent of women). Per capita consumption began to drop after 1964, when the U.S. Surgeon General reported tobacco use to be a major health hazard. Currently, 26.5 percent of adults smoke (29.5 percent of men and 23.8 percent of women). Despite the trend toward fewer smokers, the percentage of heavy smokers has risen considerably.
Although cigarette smoking is the largest single preventable cause of death and disability in the United States, most patients report that they have not been counseled by their physicians to stop smoking. This failure occurs, in part, because physicians lack adequate training in the area of smoking cessation.
Pharmacology of Nicotine
The hundreds of substances in cigarette smoke can be divided into cigarette constituents (organic matter, nicotine alkaloids, and additives) and pyrolysis products (carbon dioxide, carbon monoxide, coal tar). Carcinogens are found primarily in the particulate phase of smoke.
The smoke itself consists of mainstream smoke, which is inhaled by the smoker directly from the cigarette, and sidestream smoke, which enters the atmosphere from the lighted end of the cigarette and is inhaled by others in the vicinity. About 80 percent of environmental tobacco smoke is sidestream smoke. It contains greater concentrations of toxic and carcinogenic compounds than mainstream smoke.
The average cigarette contains about 10 mg of nicotine. A variable amount, between 1 and 2 mg, is delivered to the lungs when the cigarette is smoked. Absorption of nicotine by the lungs depends on the number of inhalations, the depth and duration of inhalations and pH of the smoke. One puff of smoke results in a measurable nicotine level in the brain within seconds. With regular use, nicotine accumulates in the body during the day and persists overnight. Nicotine readily crosses the blood-brain barrier, where it acts as an agonist on specific cholinergic receptors in the central nervous system. It is metabolized in the liver, and cotinine is its major metabolite.
Medical Complications
The medical complications of smoking may be divided into those resulting from mainstream smoke (active smoking) and those resulting from sidestream smoke (passive smoking). Table 1 lists diseases and conditions associated with active and passive smoking.
ACTIVE SMOKING
Cigarette smoking is associated with elevated rates of cancer of the lung, oral cavity, pharynx, larynx, esophagus, pancreas, bladder and kidney. It is a major risk factor for coronary artery disease and other cardiovascular problems. Smoking also increases the potential for serious adverse effects in women using oral contraceptives.
Thromboangiitis obliterans and peptic ulcer disease are exacerbated by smoking. The role of smoking in lung infections and chronic obstructive pulmonary disease (COPD) is well documented. Although pulmonary change is progressive with chronic smoking, the severity of the damage depends on individual susceptibility. Abstinence of five to ten years returns the risk of developing most smoking-related diseases to that for the non-smoking population.
Smoking depresses the senses of smell and taste, allowing smokers to avoid the unpleasant taste and odor associated with smoking. Vocal cord irritation causes chronic cough and hoarseness.
Nicotine easily crosses the placenta. An increase in fetal heart rate can be seen for 90 minutes after a pregnant woman smokes a cigarette. Heavy smokers have an increased risk of spontaneous abortion, are more likely to deliver babies small for gestational age and have an increased risk of giving birth to children with congenital abnormalities, including patent ductus arteriosus, tetralogy of Fallot, and cleft palate and lip. Children of mothers who smoked or consumed seriously during pregnancy may exhibit symptoms of hyperactivity among children and teens and may be at higher danger of cancer disease in later.