Nicotine is a highly addictive plant-derived alkaloid with stimulant properties, and the most widely used addictive xenobiotic in the world. It is related to coniine—the important alkaloid in poison hemlock—and to lobeline, which is found in Lobalia inflata, or Indian tobacco. Most nicotine is derived from members of the genus Nicotiana, collectively known as the tobacco plant, in the family Solanaceae. The most important species in human use today is Nicotiana tabacum.
The primary source of nicotine exposure is cigarette smoking, and there are over 3000 components to tobacco smoke. The health burden of cigarette smoking and use of other tobacco products is staggering. Epidemic tobacco abuse increases rates of chronic obstructive pulmonary disease (COPD), cardiovascular disease, pulmonary infections, macular degeneration, and cancers, and causes over five million deaths worldwide per year. Nicotine per se may not be the crucial factor in each of these health issues caused by tobacco products.
There are direct health effects of chronic nicotine exposure. Even in low doses, nicotine causes vasoconstriction and other cardiovascular effects related to catecholamine release, and promotes angiogenesis, neuroteratogenicity, and possibly some cancers.41 Neither these nor the long-term effects of cigarette smoking and tobacco dependency are discussed further in this chapter. Instead, this chapter is concerned with the sources, effects, and management of acute toxicity referable to nicotinic receptor stimulation and cholinergic activation.
The tobacco plant is native to the Americas, and its use most likely predates the Mayan empire. In 1492 Christopher Columbus and his crew were given tobacco by the Arawaks, but threw it away not knowing any use for it. Ramon Pane, a monk who accompanied Columbus on his second voyage to America, is credited with introducing tobacco to Europe.64
Nicotine was isolated from tobacco in 1828. The principle source of nicotine today is still tobacco products including cigarettes, cigars, pipe tobacco, chewing tobacco, and snuff. Smoking cessation products containing nicotine are increasingly available and include gums, transdermal patches, lozenges, inhaler sprays, and pills. Exposure to tobacco plants during their harvest remains an important source of occupational nicotine toxicity known as green tobacco sickness. Nicotine insecticides are no longer in widespread use in the United States, but are used in other countries and can still be purchased from some online retailers. The neonicotinoids are the only major new class of insecticide developed in the past quarter century, and despite decreased affinity for mammalian compared to invertebrate nicotinic receptors they may still cause significant toxicity in humans. The nicotine receptor partial agonists, used to aid smoking cessation, are a new class of drug that mimics the physiologic effects of nicotine.
The amount of nicotine contained in a single cigarette is highly variable, and ranges from less than 10 mg in a "low nicotine" cigarette to 30 mg in some European cigarettes (Table 84–1). Since most ...