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For other uses, see Nicotine (disambiguation).
Nicotine is an organic compound, an alkaloid found naturally throughout the tobacco plant, with a high concentration in the leaves. It constitutes circa 5% of the plant by weight. It is a potent nerve poison and is included in many insecticides. In lower concentrations, the substance is a stimulant and is one of the main factors leading to the pleasure and habit-forming qualities of tobacco smoking. In addition to the tobacco plant, nicotine is also found in lower quantities in other members of the Solanaceae (nightshade) family, which includes tomato, potato, eggplant (aubergine), and green pepper.

Table of contents
1 Chemical properties
2 Effects on the body
3 History and name
4 External links

Chemical properties

The chemical formula of nicotine is C10H14N2.

This structure is reflected in the IUPAC name 3-(2-(N-methylpyrrolidinyl))pyridine.

Nicotine is water soluble and can be extracted by leaving the cut tobacco in a glass of water for 12 hours.

The CAS number of nicotine is 54-11-5.

Effects on the body

In small doses nicotine has a stimulating effect, increasing activity, alertness and memory. Repeat users report a pleasant relaxing effect. It also increases the heart rate and blood pressure and reduces the appetite. In large doses it may cause vomiting and nausea. The LD50 is 50 mg/kg for rats and 3 mg/kg for mice.

Repeat users of nicotine often develop a physical dependency to the chemical. A report released on May 16, 1988 by United States Surgeon General C. Everett Koop stated that the addictive properties of nicotine are similar to those of heroin and cocaine; although many people do not agree with such a comparison. Withdrawal symptoms include irritability, headaches and anxiety. These symptoms may last for months or years, although they peak at around 48-72 hours.

Although the amount of nicotine inhaled with tobacco smoke is quite small (most of the substance is destroyed by the heat) it is still sufficient to cause dependence. The amount of nicotine absorbed by the body from smoking depends on many factors, including the type of tobacco, whether the smoke is inhaled, and whether a filter is used.

As nicotine enters the body, it quickly gets distributed through the bloodstream and can cross the blood-brain barrier. On average it takes about seven seconds for the substance to reach the brain. It acts on the nicotinic acetylcholine receptors. In small concentrations it increases the activity of these receptors, among other things leading to an increased flow of adrenaline, a stimulating hormone. The release of adrenaline causes an increase in heart rate, blood pressure and respiration, as well as higher glucose levels in the blood. Cotinine is a break-down product of nicotine which remains in the blood for up to 48 hours, and so can be used as an indicator of a personís exposure to smoke. In high doses, nicotine blocks the nicotinic acetylcholine receptor, which is the reason for its toxicity and its effectiveness as an insecticide.

In addition, nicotine increases dopamine levels in the reward circuits of the brain. Studies have shown that smoking tobacco inhibits monoamine oxidase (MAO), an enzyme responsible for breaking down monoaminergic neurotransmitters such as dopamine, in the brain. It is currently believed that nicotine by itself does not inhibit the production of monoamine oxidase (MAO), but that other ingredients in inhaled tobacco smoke are believed to be responsible for this activity. Thus it generates feelings of pleasure. This reaction is similar to that caused by cocaine and heroin, and is another reason people keep smoking: to sustain high dopamine levels.

It has been noted that the majority of people diagnosed with schizophrenia smoke tobacco. Estimates for the number of schizophrenics that smoke range from 75% to 90%. It is argued that the increased level of smoking in schizophrenia may be due to a desire to self-medicate with nicotine. [1] [1]

Nicotine and its metabolites are being researched for the treatment of a number of disorders, including ADHD, Parkinson's Disease and Alzheimer's Disease.

It has long been thought that tar and other chemicals in tobacco were the main cause of cancer but recent studies showed that nicotine alone has carcinogenic properties by inhibiting the natural ability of the body to get rid of cells with significant genetic damage before they turn cancerous.

History and name

Nicotine is named after the tobacco plant Nicotiana tabacum which in turn is named after Jean Nicot, who sent tobacco seeds from Portugal to Paris in 1550 and promoted its medicinal use. It was first isolated in 1828; its molecular formula was established in 1843 and it was first synthesized in 1904.

External links

{Caffeine} {Nicotine}

Sympathomimetic amines
{Cathinone} {Chlorphentermine} {Cocaine} {Diethylpropion} {Ephedrine} {Fenfluramine} {Fen-phen} {Mazindol} {Methcathinone} {Methylphenidate} {Pemoline} {Phendimetrazine} {Phenmetrazine} {Phentermine} {Pseudoephedrine}

{Amphetamine} {Benzphetamine} {Dexamphetamine} {MDMA} {Methamphetamine} {Paramethoxyamphetamine}
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