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Nicotine

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This article is about the chemical. For other uses, see Nicotine (disambiguation).

Nicotine is a potent parasympathomimetic alkaloid found in the nightshade family of plants (Solanaceae). It acts as a nicotinic acetylcholine receptor agonist. It is made in the roots and accumulates in the leaves of the plants. It constitutes approximately 0.6–3.0% of the dry weight of tobacco[1] and is present in the range of 2–7 µg/kg of various edible plants.[2] It functions as an antiherbivore chemical; therefore, nicotine was widely used as an insecticide in the past[3][4][5] and nicotine analogs such as imidacloprid are currently widely used.

In smaller doses (an average cigarette yields about 1 mg of absorbed nicotine), the substance acts as a stimulant in mammals, while high amounts (30–60 mg[6]) can be fatal.[7] This stimulant effect is likely a major contributing factor to the dependence-forming properties of tobacco smoking.[citation needed] According to the American Heart Association, nicotine addiction has historically been one of the hardest addictions to break, while the pharmacological and behavioral characteristics that determine tobacco addiction are similar to those determining addiction to heroin and cocaine. The nicotine content of popular American-brand cigarettes has slowly increased over the years, and one study found that there was an average increase of 1.78% per year between the years of 1998 and 2005. This was found for all major market categories of cigarettes.[8]

Research in 2011 has found that nicotine inhibits chromatin-modifying enzymes (class I and II histone deacetylases) which increases the ability of cocaine to cause an addiction.[9]

Contents

1 History and name

1.1 Historical use of nicotine as an insecticide

2 Chemistry

3 Optical activity

4 Biosynthesis

5 Pharmacology

5.1 Pharmacokinetics

5.2 Detection of use

5.2.1 Medical detection

5.3 Pharmacodynamics

5.3.1 In the central nervous system

5.3.2 In the sympathetic nervous system

5.3.3 In adrenal medulla

6 Psychoactive effects

7 Side effects

8 Dependence and withdrawal

8.1 Immunology prevention

9 Toxicology

10 Therapeutic uses

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11 In media

12 See also

13 References

14 Further reading

15 External links

History and name

Nicotine is named after the tobacco plant Nicotiana tabacum, which in turn is named after the French ambassador in Portugal, Jean Nicot de Villemain, who sent tobacco and seeds to Paris in 1560, and who promoted their medicinal use. The tobacco and seeds were brought to ambassador Nicot from Brazil by Luis de Gois, a Portuguese colonist in São Paulo. Nicotine was first isolated from the tobacco plant in 1828 by physician Wilhelm Heinrich Posselt and chemist Karl Ludwig Reimann of Germany, who considered it a poison.[10][11] Its chemical empirical formula was described by Melsens in 1843,[12] its structure was discovered by Adolf Pinner and Richard Wolffenstein in 1893,[13][clarification needed] and it was first synthesized by Amé Pictet and A. Rotschy in 1904.[14]

Historical use of nicotine as an insecticide

Tobacco was introduced to Europe in 1559, and by the late 17th century, it was used not only for smoking but also as an insecticide. After World War II, over 2,500 tons of nicotine insecticide (waste from the tobacco industry) were used worldwide, but by the 1980s the use of nicotine insecticide had declined below 200 tons. This was due to the availability of other insecticides that are cheaper and less harmful to mammals.[4]

Currently, nicotine is a permitted pesticide for organic farming because it is derived from a botanical source. Nicotine sulfate sold for use as a pesticide is labeled "DANGER," indicating that it is highly toxic.[5] However, in 2008, the EPA received a request to cancel the registration of the last nicotine pesticide registered in the United States.[15] This request was granted, and after 1 January 2014, this pesticide will not be available for sale.[16]

Chemistry

Nicotine is a hygroscopic, oily liquid that is miscible with water in its base form. As a nitrogenous base, nicotine forms salts with acids that are usually solid and water soluble, for example nicotine sulfate which, being a solid, is easier to handle in its use as an insecticide. (For retail use it is sold as solution in water ready for spraying.)[5] Its flash point is 95°C and its auto-ignition temperature is 244°C.[17]

Optical activity

Nicotine is optically active, having two enantiomeric forms. The naturally occurring form of nicotine is levorotatory with a specific rotation of [α]D = –166.4° ((−)-nicotine). The dextrorotatory form, (+)-nicotine is physiologically less active than (–)-nicotine. (−)-nicotine is more toxic than (+)-nicotine.[18] The salts of (+)-nicotine are usually dextrorotatory.

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