nicotine
(nĭk'ō-tēn 
)
(-tĭn)
[L. nicotiana, tobacco]
A poisonous, highly addictive alkaloid found in all parts of the tobacco plant, but esp. in the leaves. When pure, it is a colorless oily fluid with little odor but a sharp burning taste. On exposure to air or in crude materials, it becomes deep brown with a characteristic tobacco-like smell. Cigarettes, cigars, and chewing tobacco contain varying amounts of nicotine. During cigarette smoking the blood nicotine level rises 10 to 15 sec after each puff. A person's average daily nicotine intake varies with the number and type of tobacco products used, the depth of inhalation during smoking, and any exposure to second-hand smoke. Many smokers experience withdrawal symptoms when their daily nicotine exposures fall below 5 mg/day.
SEE: cancer, lung; cotinine; nicotine chewing gum; nicotine poisoning, acute; patch, nicotine; tobacco, smokeless.
Smoking during pregnancy is associated with high risk for low-birth-weight infants, prematurity, and perinatal respiratory infections.
Symptoms: In healthy subjects who are not accustomed to using nicotine, nausea, vomiting, dizziness, headache, sleep disturbances, and sweating are commonly reported.
Treatment: Nicotine replacement therapy, administered by chewing gum, nasal spray, transdermal patch, or inhaler, can help motivated smokers to abstain from tobacco use. This type of therapy should be offered to patients who have specific plans to quit and who have received some form of structured counseling about smoking cessation.
Nicotine replacement is sometimes helpful in managing active ulcerative colitis, esp. in former smokers with the disease. Other treatments for nicotine addiction include some antidepressant medications, e.g., bupropion, and nicotine-receptor blocking drugs.