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{{otheruses4|the chemical compound|other uses|Nicotine (disambiguation)}}

{{Drugbox|

|IUPAC_name = ''(S)-3-(1-Methyl-2-pyrroli-
dinyl)pyridine''
| image=Nicotine-2D-skeletal.png
| image2=Nicotine-3D-vdW.png
| CAS_number=54-11-5
| ATC_prefix=N07
| ATC_suffix=BA01
| ATC_supplemental=
| PubChem=942
| smiles = C1=CC=NC=C1[C@@H]2CCCN2C
| DrugBank=
| C=10 | H=14 | N=2 |
| molecular_weight = 162.26 g/mole
| density= 1.01
| boiling_point= 247
| melting_point= -79
| bioavailability=
| metabolism =
| elimination_half-life= 2 hours
| excretion =
| pregnancy_US = Category X
| legal_AU = Unscheduled
| legal_CA =
| legal_UK = Unscheduled
| legal_US =
| legal_status =
| routes_of_administration= [[Tobacco smoking|Smoked (as tobacco)]], [[Insufflate]]d (as snuff), [[Nicotine gum|Chewed]]
| dependency_liability = Medium to high
}}


'''Nicotine''' is an [[alkaloid]] found in the [[nightshade]] family of plants (''Solanaceae''), predominantly in [[tobacco]] and [[coca]], and in lower quantities in [[tomato]], [[potato]], [[eggplant]] (aubergine), and [[Bell pepper|green pepper]]. Nicotine has been found to constitute approximately 0.6 - 3.0% of dry weight of tobacco,<ref>{{cite web |url=http://dccps.nci.nih.gov/tcrb/monographs/9/m9_3.PDF |title=Smoking and Tobacco Control Monograph No. 9}}</ref> with [[biosynthesis]] taking place in the [[root]]s, and accumulating in the [[leaves]]. It functions as an [[Plant defense against herbivory|antiherbivore chemical]], being a potent [[neurotoxin]] with particular specificity to [[insect]]s; therefore nicotine was widely used as an [[insecticide]] in the past, and currently nicotine derivatives such as [[imidacloprid]] continue to be widely used.
'''Nicotine''' is an [[alkaloid]] found in the [[nightshade]] family of plants (''Solanaceae''), predominantly in [[tobacco]] and [[coca]], and in lower quantities in [[tomato]], [[potato]], [[eggplant]] (aubergine), and [[Bell pepper|green pepper]]. Nicotine has been found to constitute approximately 0.6 - 3.0% of dry weight of tobacco,<ref>{{cite web |url=http://dccps.nci.nih.gov/tcrb/monographs/9/m9_3.PDF |title=Smoking and Tobacco Control Monograph No. 9}}</ref> with [[biosynthesis]] taking place in the [[root]]s, and accumulating in the [[leaves]]. It functions as an [[Plant defense against herbivory|antiherbivore chemical]], being a potent [[neurotoxin]] with particular specificity to [[insect]]s; therefore nicotine was widely used as an [[insecticide]] in the past, and currently nicotine derivatives such as [[imidacloprid]] continue to be widely used.
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When a [[cigarette]] is smoked, nicotine-rich blood passes from the [[lung]]s to the [[brain]] within seven seconds and immediately stimulates the release of many chemical messengers including [[acetylcholine]], [[norepinephrine]], [[epinephrine]], [[vasopressin]], [[arginine]], [[dopamine]], and [[beta-endorphin]]. This results in enhanced pleasure, decreased [[anxiety]], and a state of alert [[relaxation]]. Nicotine enhances [[attention|concentration]] and [[learning]] due to the increase of [[acetylcholine]]. It also enhances [[alertness]] due to the increases of [[acetylcholine]] and [[norepinephrine]]. [[Arousal]] is increased by the increase of [[norepinephrine]]. [[Pain]] is reduced by the increases of [[acetylcholine]] and [[beta-endorphin]]. [[Anxiety]] is reduced by the increase of [[beta-endorphin]]. The effects of nicotine last from five minutes to two hours. Most cigarettes (in the smoke inhaled) contain 0.1 to 2.8 milligrams of nicotine.{{Fact|date=January 2008}}
When a [[cigarette]] is smoked, nicotine-rich blood passes from the [[lung]]s to the [[brain]] within seven seconds and immediately stimulates the release of many chemical messengers including [[acetylcholine]], [[norepinephrine]], [[epinephrine]], [[vasopressin]], [[arginine]], [[dopamine]], and [[beta-endorphin]]. This results in enhanced pleasure, decreased [[anxiety]], and a state of alert [[relaxation]]. Nicotine enhances [[attention|concentration]] and [[learning]] due to the increase of [[acetylcholine]]. It also enhances [[alertness]] due to the increases of [[acetylcholine]] and [[norepinephrine]]. [[Arousal]] is increased by the increase of [[norepinephrine]]. [[Pain]] is reduced by the increases of [[acetylcholine]] and [[beta-endorphin]]. [[Anxiety]] is reduced by the increase of [[beta-endorphin]]. The effects of nicotine last from five minutes to two hours. Most cigarettes (in the smoke inhaled) contain 0.1 to 2.8 milligrams of nicotine.{{Fact|date=January 2008}}


Research<ref>{{cite book

| last = Einstein
| first = Stanley
| authorlink = Stanley Einstein
| title = Drug and Alcohol Use: Issues and Factors
| publisher = [[Springer]]
| date = 1989
| pages = 101-118
| isbn = 0306413787
}}</ref> suggests that, when smokers wish to achieve a stimulating effect, they take short quick puffs, which produce a low level of blood nicotine. This stimulates [[nerve transmission]]. When they wish to relax, they take deep puffs, which produce a high level of blood nicotine, which depresses the passage of [[nerve impulses]], producing a mild sedative effect. At low doses, nicotine potently enhances the actions of [[norepinephrine]] and [[dopamine]] in the brain, causing a drug effect typical of those of [[psychostimulants]]. At higher doses, nicotine enhances the effect of [[serotonin]] and [[opiate]] activity, producing a calming, [[analgesic|pain-killing]] effect. Nicotine is unique in comparison to most [[drug]]s, as its profile changes from [[stimulant]] to [[sedative]]/[[pain killer]] in increasing [[dosage]]s and use.
}}</ref> suggests that, when smokers wish to achieve a stimulating effect, they take short quick puffs, which produce a low level of blood nicotine. This stimulates [[nerve transmission]]. When they wish to relax, they take deep puffs, which produce a high level of blood nicotine, which depresses the passage of [[nerve impulses]], producing a mild sedative effect. At low doses, nicotine potently enhances the actions of [[norepinephrine]] and [[dopamine]] in the brain, causing a drug effect typical of those of [[psychostimulants]]. At higher doses, nicotine enhances the effect of [[serotonin]] and [[opiate]] activity, producing a calming, [[analgesic|pain-killing]] effect. Nicotine is unique in comparison to most [[drug]]s, as its profile changes from [[stimulant]] to [[sedative]]/[[pain killer]] in increasing [[dosage]]s and use.


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There is significant anecdotal evidence from pharmacist vendors, via their customers, about addiction to [[nicotine gum]] or [[nicotine patches]].
There is significant anecdotal evidence from pharmacist vendors, via their customers, about addiction to [[nicotine gum]] or [[nicotine patches]].


==Toxicology==

The [[LD50|LD<sub>50</sub>]] of nicotine is 50&nbsp;mg/kg for [[rat]]s and 3&nbsp;mg/kg for [[mouse|mice]]. 40&ndash;60 mg (0.5-1.0 mg/kg) can be a lethal dosage for adult humans.<ref>{{cite journal
| author = Okamoto M., Kita T., Okuda H., Tanaka T., Nakashima T.
| title = Effects of aging on acute toxicity of nicotine in rats
| journal = Pharmacol Toxicol.
| year = 1994
| volume = 75
| issue = 1
| pages = 1-6
| doi =
}}</ref> <ref>[http://www.inchem.org/documents/pims/chemical/nicotine.htm#PartTitle:7.%20TOXICOLOGY IPCS INCHEM]</ref> This makes it an extremely deadly [[poison]]. It is more toxic than many other alkaloids such as [[cocaine]], which has an LD<sub>50</sub> of 95.1 mg/kg when administered to mice.


The [[carcinogen]]ic properties of nicotine in standalone form, separate from tobacco smoke, have not been evaluated by the [[International Agency for Research on Cancer|IARC]], and it has not been assigned to an official carcinogen group. The currently available literature indicates that nicotine, on its own, does not promote the development of [[cancer]] in healthy tissue and has no [[mutagen]]ic properties. Its [[Teratogenesis|teratogenic]] properties have not yet been adequately researched, and while the likelihood of birth defects caused by nicotine is believed to be very small or nonexistent, nicotine replacement product manufacturers recommend consultation with a physician before using a [[nicotine patch]] or [[nicotine gum]] while pregnant or nursing. However, nicotine and the increased [[Nicotinic acetylcholine receptor|cholinergic]] activity it causes have been shown to impede [[apoptosis]]{{Fact|date=April 2007}}, which is one of the methods by which the body destroys unwanted cells ([[programmed cell death]]). Since [[apoptosis]] helps to remove mutated or damaged cells that may eventually become cancerous, the inhibitory actions of nicotine create a more favourable environment for cancer to develop. Thus nicotine plays an indirect role in [[carcinogenesis]]. It is also important to note that its addictive properties are often the primary motivating factor for [[tobacco smoking]], contributing to the proliferation of cancer.
The [[carcinogen]]ic properties of nicotine in standalone form, separate from tobacco smoke, have not been evaluated by the [[International Agency for Research on Cancer|IARC]], and it has not been assigned to an official carcinogen group. The currently available literature indicates that nicotine, on its own, does not promote the development of [[cancer]] in healthy tissue and has no [[mutagen]]ic properties. Its [[Teratogenesis|teratogenic]] properties have not yet been adequately researched, and while the likelihood of birth defects caused by nicotine is believed to be very small or nonexistent, nicotine replacement product manufacturers recommend consultation with a physician before using a [[nicotine patch]] or [[nicotine gum]] while pregnant or nursing. However, nicotine and the increased [[Nicotinic acetylcholine receptor|cholinergic]] activity it causes have been shown to impede [[apoptosis]]{{Fact|date=April 2007}}, which is one of the methods by which the body destroys unwanted cells ([[programmed cell death]]). Since [[apoptosis]] helps to remove mutated or damaged cells that may eventually become cancerous, the inhibitory actions of nicotine create a more favourable environment for cancer to develop. Thus nicotine plays an indirect role in [[carcinogenesis]]. It is also important to note that its addictive properties are often the primary motivating factor for [[tobacco smoking]], contributing to the proliferation of cancer.
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The primary therapeutic use of nicotine is in treating nicotine dependence in order to eliminate [[smoking]] with its risks to health. Controlled levels of nicotine are given to patients through gums, dermal patches, lozenges, or nasal sprays in an effort to wean them off their dependence.
The primary therapeutic use of nicotine is in treating nicotine dependence in order to eliminate [[smoking]] with its risks to health. Controlled levels of nicotine are given to patients through gums, dermal patches, lozenges, or nasal sprays in an effort to wean them off their dependence.


However, in a few situations, smoking has been observed to apparently be of therapeutic value to patients.
These are often referred to as "Smoker’s Paradoxes"<ref name="cohen">
{{cite journal
| last = Cohen
| first = David J.
| authorlink =
| coauthors = Michel Doucet, Donald E. Cutlip, Kalon K.L. Ho, Jeffrey J. Popma, Richard E. Kuntz
| title = Impact of Smoking on Clinical and Angiographic Restenosis After Percutaneous Coronary Intervention
| journal = Circulation
| volume = 104
| issue =
| pages = 773
| date = 2001
| url = http://www.data-yard.net/34/circulation_2001_104_773.htm
| doi =
| id =
| accessdate = 2006-11-06}}
</ref>. Although in most cases the actual mechanism is understood only poorly or not at all, it is generally believed that the principal beneficial action is due to the nicotine administered, and that administration of nicotine without smoking may be as beneficial as smoking, without the higher risk to health due to [[tar]] and other ingredients found in [[tobacco]].


For instance, recent studies suggest that smokers require less frequent repeated [[revascularization]] after [[percutaneous coronary intervention]] (PCI).<ref name="cohen"/> Risk of [[ulcerative colitis]] has been frequently shown to be reduced by smokers on a dose-dependent basis; the effect is eliminated if the individual stops smoking.<ref name="ohcm">Longmore, M., Wilkinson, I., Torok, E. Oxford Handbook of Clinical Medicine (Fifth Edition) p. 232</ref><ref>
{{cite journal
| last = Green
| first = JT
| authorlink =
| coauthors = Richardson C, Marshall RW, Rhodes J, McKirdy HC, Thomas GA, Williams GT
| title = Nitric oxide mediates a therapeutic effect of nicotine in ulcerative colitis
| journal = Aliment Pharmacol Ther
| volume = 14
| issue = 11
| pages = 1429-1434
| date = November, 2000
| url = http://www.data-yard.net/22/ncbi.htm
| doi =
| id =PMID: 11069313
| accessdate = 2006-11-06}}</ref>
Smoking also appears to interfere with development of [[Kaposi's sarcoma]],<ref>
{{cite news
| last =
| first =
| coauthors =
| title = Smoking Cuts Risk of Rare Cancer
| work =
| pages =
| language = English
| publisher = UPI
| date = March 29, 2001
| url = http://www.data-yard.net/10b/kaposi.htm
| accessdate = 2006-11-06}}
</ref>
[[breast cancer]] among women carrying the very high risk [[BRCA]] gene,<ref>
{{cite news
| last = Recer
| first = Paul
| coauthors =
| title = Cigarettes May Have an Up Side
| work =
| pages =
| language = English
| publisher = AP
| date = May 19, 1998
| url = http://www.forces.org/evidence/files/brea.htm
| accessdate = 2006-11-06}}
</ref>
[[preeclampsia]],<ref>
{{cite journal
| last = Lain
| first = Kristine Y.
| authorlink =
| coauthors = Robert W. Powers, Marijane A. Krohn, Roberta B. Ness, William R. Crombleholme,
James M. Roberts
| title = Urinary cotinine concentration confirms the reduced risk of preeclampsia with tobacco exposure
| journal = American Journal of Obstetrics and Gynecology
| volume = 181
| issue = 5
| pages = 908-14
| date = November 1991
| url = http://www.data-yard.net/2/13/ajog.htm
| doi =
| id = PMID: 11422156
| accessdate = 2006-11-06}}
</ref>
and [[atopy|atopic disorder]]s such as [[allergic asthma]].<ref>
{{cite journal
| last = Hjern
| first = A
| authorlink =
| coauthors = Hedberg A, Haglund B, Rosen M
| title = Does tobacco smoke prevent atopic disorders? A study of two generations of Swedish residents
| journal = Clin Exp Allergy
| volume = 31
| issue = 6
| pages = 908-914
| publisher =
| date = June 2001
| url = http://www.data-yard.net/30/asthma.htm
| doi =
| id = PMID: 11422156
| accessdate = 2006-11-06}}</ref>
A plausible mechanism of action in these cases may be nicotine acting as an [[Inflammation|anti-inflammatory agent]], and interfering with the inflammation-related disease process, as nicotine has vasoconstrictive effects.<ref name="sciam">{{cite journal | author=Lisa Melton | title=Body Blazes | journal=Scientific American | date=June 2006 | pages=p.24 | url=http://www.sciam.com/article.cfm?chanID=sa006&colID=5&articleID=00080902-A2CF-146C-9D1E83414B7F0000}}</ref>


With regard to [[neurology|neurological diseases]], a large body of evidence suggests that the risks of [[Parkinson's disease]] or [[Alzheimer's disease]] might be twice as high for non-smokers than for smokers.<ref>

{{cite journal
| last = Fratiglioni
| first = L
| authorlink =
| coauthors = Wang HX
| title = Smoking and Parkinson's and Alzheimer's disease: review of the epidemiological studies
| journal = Behav Brain Res
| volume = 113
| issue = 1-2
| pages = 117-120
|date=August 2000
| url = http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10942038&dopt=Citation
| doi =
| id = PMID: 10942038
| accessdate = 2006-11-06}}
</ref>
Many such papers regarding Alzheimer's disease<ref>
{{cite web
| last = Thompson
| first = Carol
| authorlink =
| coauthors =
| title = Alzheimer's disease is associated with non-smoking
| work =
| date =
| url = http://www.forces.org/evidence/carol/carol16.htm
| format =
| doi =
| accessdate =2006-11-06}}
</ref>
and Parkinson's Disease<ref>
{{cite web
| last = Thompson
| first = Carol
| authorlink =
| coauthors =
| title = Parkinson's disease is associated with non-smoking
| work =
| date =
| url = http://www.forces.org/evidence/carol/carol36.htm
| format =
| doi =
| accessdate =2006-11-06}}
</ref>
have been published.


Recent studies have indicated that nicotine can be used to help adults suffering from [[Autosomal dominant nocturnal frontal lobe epilepsy]]. The same areas that cause seizures in that form of [[epilepsy]] are also responsible for processing nicotine in the brain.<ref>{{cite web |url=http://www.cnsforum.com/commenteditem/3c5dccdc-27fb-4b80-9516-ab81e3e4ea6c/default.aspx |title=Nicotine as an antiepileptic agent in ADNFLE: An n-of-one study}}</ref>
Recent studies have indicated that nicotine can be used to help adults suffering from [[Autosomal dominant nocturnal frontal lobe epilepsy]]. The same areas that cause seizures in that form of [[epilepsy]] are also responsible for processing nicotine in the brain.<ref>{{cite web |url=http://www.cnsforum.com/commenteditem/3c5dccdc-27fb-4b80-9516-ab81e3e4ea6c/default.aspx |title=Nicotine as an antiepileptic agent in ADNFLE: An n-of-one study}}</ref>
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The therapeutic use of nicotine as a means of appetite-control and to promote weight loss is anecdotally supported by many ex-smokers who claim to put on weight after quitting. However studies of nicotine in mice <ref>NIH, online at [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=954834&dopt=Abstract]</ref> suggests it may play a role in weight-loss that is independent of appetite. And studies involving the elderly suggest that nicotine affects not only weight loss, but also prevents some weight gain. <ref>Cigarette Smoking and Weight Loss in Nursing Home Residents
The therapeutic use of nicotine as a means of appetite-control and to promote weight loss is anecdotally supported by many ex-smokers who claim to put on weight after quitting. However studies of nicotine in mice <ref>NIH, online at [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=954834&dopt=Abstract]</ref> suggests it may play a role in weight-loss that is independent of appetite. And studies involving the elderly suggest that nicotine affects not only weight loss, but also prevents some weight gain. <ref>Cigarette Smoking and Weight Loss in Nursing Home Residents


[http://www.priory.com/med/cigsmoking.htm]</ref>
\

== See also ==
*[[Addiction]]
*[[Cigarette]]
*[[Dipping tobacco]]
*[[Drug addiction]]
*[[Nicogel]]
*[[Nicotini]]
*[[NicVAX]]
*[[Psychoactive drug]]
*[[Snuff]]
*[[Snus]]

==External Links==
*[http://www.stopsmoking.net/about_add.html Description of nicotine addiction]

==References==
{{reflist|colwidth=35em}}

== Further reading ==
* Guardian article: [http://www.guardian.co.uk/smoking/Story/0,2763,1263918,00.html "Nicotine could soon be rehabilitated as a treatment for schizophrenia, Alzheimer's and Parkinson's diseases, as well as hyperactivity disorders."]
* Nicotine Therapy for ADNFLE: [http://www.cnsforum.com/commenteditem/3c5dccdc-27fb-4b80-9516-ab81e3e4ea6c/default.aspx "Nicotine as an antiepileptic agent in ADNFLE: An n-of-one study"]
* Minna, John D.: [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=151841 "Nicotine exposure and bronchial epithelial cell nicotinic acetylcholine receptor expression in the pathogenesis of lung cancer"]
* [[James Fallon|Fallon, J.H.]], et al. (2005) Gender: A major determinant of brain response to nicotine. International Journal of Neuropharmacology. 8:1-10. [http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=282494]
* West, Kip A., et al.: [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=151834 "Rapid Akt activation by nicotine and a tobacco carcinogen modulates the phenotype of normal human airway epithelial cells"]
* [http://www.nida.nih.gov/researchreports/nicotine/nicotine.html National Institute on Drug Abuse]
*Powledge TM (2004) Nicotine as therapy. PLoS Biol 2(11): e404.: [http://biology.plosjournals.org/perlserv?request=get-document&doi=10.1371/journal.pbio.0020404]
*Erowid information on tobacco[http://www.erowid.org/plants/tobacco/tobacco.shtml]

{{stimulants}}

{{Drugs used in addictive disorders}}

[[Category:Addiction]]
[[Category:Alkaloids]]
[[Category:Health risks]]
[[Category:Neurotoxins]]
[[Category:Nitrogen heterocycles]]
[[Category:Nicotinic agonists]]
[[Category:Plant toxin insecticides]]
[[Category:Pyridines]]
[[Category:Pyrrolidines]]
[[Category:Stimulants]]
[[Category:Tobacco]]

[[ar:نيكوتين]]
[[bg:Никотин]]
[[ca:Nicotina]]
[[cs:Nikotin]]
[[da:Nikotin]]
[[de:Nikotin]]
[[el:Νικοτίνη]]
[[eo:Nikotino]]
[[es:Nicotina]]
[[et:Nikotiin]]
[[fa:نیکوتین]]
[[fr:Nicotine]]
[[gl:Nicotina]]
[[he:ניקוטין]]
[[hu:Nikotin]]
[[id:Nikotin]]
[[is:Nikótín]]
[[it:Nicotina]]
[[ja:ニコチン]]
[[ko:니코틴]]
[[lt:Nikotinas]]
[[ms:Nikotin]]
[[nl:Nicotine]]
[[no:Nikotin]]
[[nn:Nikotin]]
[[pl:Nikotyna]]
[[pt:Nicotina]]
[[ro:Nicotină]]
[[ru:Никотин]]
[[simple:Nicotine]]
[[sk:Nikotín]]
[[sl:Nikotin]]
[[sr:Никотинска зависност]]
[[su:Nikotin]]
[[fi:Nikotiini]]
[[sv:Nikotin]]
[[th:นิโคติน]]
[[vi:Nicotin]]
[[tr:Nikotin]]
[[yi:ניקאטין]]
[[zh:尼古丁]]

Revision as of 15:03, 17 March 2008

Nicotine
Clinical data
Dependence
liability
Medium to high
Routes of
administration
Smoked (as tobacco), Insufflated (as snuff), Chewed
ATC code
Legal status
Legal status
Pharmacokinetic data
Elimination half-life2 hours
Identifiers
  • (S)-3-(1-Methyl-2-pyrroli- dinyl)pyridine
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.000.177 Edit this at Wikidata
Chemical and physical data
FormulaC10H14N2
Molar mass162.26 g/mole g·mol−1
3D model (JSmol)
Density1.01 g/cm3
Melting point−79 °C (−110 °F)
Boiling point247 °C (477 °F)
  • C1=CC=NC=C1[C@@H]2CCCN2C

Nicotine is an alkaloid found in the nightshade family of plants (Solanaceae), predominantly in tobacco and coca, and in lower quantities in tomato, potato, eggplant (aubergine), and green pepper. Nicotine has been found to constitute approximately 0.6 - 3.0% of dry weight of tobacco,[2] with biosynthesis taking place in the roots, and accumulating in the leaves. It functions as an antiherbivore chemical, being a potent neurotoxin with particular specificity to insects; therefore nicotine was widely used as an insecticide in the past, and currently nicotine derivatives such as imidacloprid continue to be widely used.

In low concentrations (an average cigarette yields about 1 mg of absorbed nicotine), the substance acts as a stimulant in mammals and is one of the main factors responsible for the dependence-forming properties of tobacco smoking. According to the American Heart Association, "Nicotine addiction has historically been one of the hardest addictions to break." The pharmacological and behavioral characteristics that determine tobacco addiction are similar to those that determine addiction to drugs such as heroin and cocaine.[3]

History and name

Nicotine is named after the tobacco plant Nicotiana tabacum, which in turn is named after Jean Nicot, French ambassador in Portugal, who sent tobacco and seeds from Brazil to Paris in 1560 and promoted their medicinal use. Nicotine was first isolated from the tobacco plant in 1828 by German chemists Posselt & Reimann. Its chemical empirical formula was described by Melsens in 1843, and it was first synthesized by A. Pictet and Crepieux in 1893.

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. Nicotine easily penetrates the skin. As shown by the physical data, free base nicotine will burn at a temperature below its boiling point, and its vapors will combust at 308K (35°C or 95°F) in air despite a low vapor pressure. Because of this, most of the nicotine is burned when a cigarette is smoked; however, enough is inhaled to provide the desired effects.

Pharmacology

Pharmacokinetics

As nicotine enters the body, it is distributed quickly through the bloodstream and can cross the blood-brain barrier. On average it takes about seven seconds for the substance to reach the brain when inhaled. The half life of nicotine in the body is around two hours[4]. The amount of nicotine inhaled with tobacco smoke is a fraction of the amount contained in the tobacco leaves. 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. For chewing tobacco, dipping tobacco and snuff, which are held in the mouth between the lip and gum, or taken in the nose, the amount released into the body tends to be much greater than smoked tobacco. Nicotine is metabolized in the liver by cytochrome P450 enzymes (mostly CYP2A6, and also by CYP2B6). A major metabolite is cotinine.

Pharmacodynamics

Nicotine acts on the nicotinic acetylcholine receptors, specifically the ganglion type nicotinic receptor and one CNS type nicotinic receptor. The former is present e.g. in the adrenal medulla and the latter in the CNS. In small concentrations it increases the activity of these receptors.

In adrenal medulla

By binding to ganglion type nicotinic receptors the adrenal medulla nicotine increases flow of adrenaline (epinephrine), a stimulating hormone. By binding to the receptors, it causes cell depolarization and an influx of calcium through voltage-gated calcium channels. Calcium triggers the exocytosis of chromaffin granules and thus the release of epinephrine (and norepinephrine) into the bloodstream.

The release of adrenaline causes an increase in heart rate, blood pressure and respiration, as well as higher blood glucose levels [5]

Cotinine is a byproduct of the metabolism of nicotine which remains in the blood for up to 48 hours and can be used as an indicator of a person's exposure to smoke.

In high doses, nicotine will cause a blocking of the nicotinic acetylcholine receptor, which is the reason for its toxicity and its effectiveness as an insecticide.[citation needed]

In CNS

By binding to CNS type nicotinic receptors, nicotine increases dopamine levels in the reward circuits of the brain. In this way, it activates the reward system and generates feelings of pleasure, similar to that caused by cocaine and other stimulants.

Furthermore, nicotine activates the sympathetic nervous system[citation needed], acting via splanchnic nerves to the adrenal medulla, stimulates the release of epinephrine. Acetylcholine released by preganglionic sympathetic fibers of these nerves acts on nicotinic acetylcholine receptors, causing the release of epinephrine (and norepinephrine) into the bloodstream.

Studies have shown that other ingredients in inhaled tobacco smoke (not nicotine by itself) inhibits the production of monoamine oxidase (MAO)[6], an enzyme responsible for breaking down monoaminergic neurotransmitters such as dopamine in the brain.

Psychoactive effects

Nicotine's mood-altering effects are different by report. First causing a release of glucose from the liver and epinephrine (adrenaline) from the adrenal medulla, it causes stimulation. Users report feelings of relaxation, calmness, and alertness. It is even reported to produce a mildly euphoric state. By reducing the appetite and raising the metabolism, some smokers may lose weight as a consequence. It also allows the mouth to be stimulated without food, and the taste of tobacco smoke may curb the appetite.[citation needed]

When a cigarette is smoked, nicotine-rich blood passes from the lungs to the brain within seven seconds and immediately stimulates the release of many chemical messengers including acetylcholine, norepinephrine, epinephrine, vasopressin, arginine, dopamine, and beta-endorphin. This results in enhanced pleasure, decreased anxiety, and a state of alert relaxation. Nicotine enhances concentration and learning due to the increase of acetylcholine. It also enhances alertness due to the increases of acetylcholine and norepinephrine. Arousal is increased by the increase of norepinephrine. Pain is reduced by the increases of acetylcholine and beta-endorphin. Anxiety is reduced by the increase of beta-endorphin. The effects of nicotine last from five minutes to two hours. Most cigarettes (in the smoke inhaled) contain 0.1 to 2.8 milligrams of nicotine.[citation needed]

Research[7] suggests that, when smokers wish to achieve a stimulating effect, they take short quick puffs, which produce a low level of blood nicotine. This stimulates nerve transmission. When they wish to relax, they take deep puffs, which produce a high level of blood nicotine, which depresses the passage of nerve impulses, producing a mild sedative effect. At low doses, nicotine potently enhances the actions of norepinephrine and dopamine in the brain, causing a drug effect typical of those of psychostimulants. At higher doses, nicotine enhances the effect of serotonin and opiate activity, producing a calming, pain-killing effect. Nicotine is unique in comparison to most drugs, as its profile changes from stimulant to sedative/pain killer in increasing dosages and use.

A 21 mg patch applied to the left arm

Nicotine gum and nicotine patches are available, usually in 2-mg or 4-mg doses of gum, that do not have all the other ingredients in smoked tobacco. They appear to be not as addictive or as pleasurable, and, it is claimed, have fewer side-effects [citation needed]. Whether all the other psychoactive effects also occur has not been well-studied.

Dependence

Modern research shows that nicotine acts on the brain to produce a number of effects. Specifically, its addictive nature has been found to show that nicotine activates reward pathways—the circuitry within the brain that regulates feelings of pleasure and euphoria. [8]

Dopamine is one of the key neurotransmitters actively involved in the brain. Research shows that by increasing the levels of dopamine within the reward circuits in the brain, nicotine acts as a chemical with intense addictive qualities. In many studies it has been shown to be more addictive than cocaine and heroin, though chronic treatment has an opposite effect on reward thresholds. Like other physically addictive drugs, nicotine causes down-regulation of the production of dopamine and other stimulatory neurotransmitters as the brain attempts to compensate for artificial stimulation. In addition, the sensitivity of nicotinic acetylcholine receptors decreases. To compensate for this compensatory mechanism, the brain in turn upregulates the number of receptors, convoluting its regulatory effects with compensatory mechanisms meant to counteract other compensatory mechanisms. The net effect is an increase in reward pathway sensitivity, opposite of other drugs of abuse (namely cocaine and heroin, which reduce reward pathway sensitivity)[citation needed]. This neuronal brain alteration persists for months after administration ceases. Due to an increase in reward pathway sensitivity, nicotine withdrawal is relatively mild compared to ethanol or heroin withdrawal.[citation needed] Nicotine also has the potential to cause dependence in many animals other than humans. Mice have been administered nicotine and exhibit withdrawal reactions when its administration is stopped.[9]

A study found that nicotine exposure in adolescent mice retards the growth of the dopamine system, thus increasing the risk of substance abuse during adulthood.[10]

There is significant anecdotal evidence from pharmacist vendors, via their customers, about addiction to nicotine gum or nicotine patches.

Toxicology

The LD50 of nicotine is 50 mg/kg for rats and 3 mg/kg for mice. 40–60 mg (0.5-1.0 mg/kg) can be a lethal dosage for adult humans.[11] [12] This makes it an extremely deadly poison. It is more toxic than many other alkaloids such as cocaine, which has an LD50 of 95.1 mg/kg when administered to mice.

The carcinogenic properties of nicotine in standalone form, separate from tobacco smoke, have not been evaluated by the IARC, and it has not been assigned to an official carcinogen group. The currently available literature indicates that nicotine, on its own, does not promote the development of cancer in healthy tissue and has no mutagenic properties. Its teratogenic properties have not yet been adequately researched, and while the likelihood of birth defects caused by nicotine is believed to be very small or nonexistent, nicotine replacement product manufacturers recommend consultation with a physician before using a nicotine patch or nicotine gum while pregnant or nursing. However, nicotine and the increased cholinergic activity it causes have been shown to impede apoptosis[citation needed], which is one of the methods by which the body destroys unwanted cells (programmed cell death). Since apoptosis helps to remove mutated or damaged cells that may eventually become cancerous, the inhibitory actions of nicotine create a more favourable environment for cancer to develop. Thus nicotine plays an indirect role in carcinogenesis. It is also important to note that its addictive properties are often the primary motivating factor for tobacco smoking, contributing to the proliferation of cancer.

At least one study has concluded that exposure to nicotine alone, not simply as a component of cigarette smoke, could be responsible for some of the neuropathological changes observed in infants dying from Sudden Infant Death Syndrome (SIDS).[13]

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 was recently argued that the increased level of smoking in schizophrenia may be due to a desire to self-medicate with nicotine. [14] [15] More recent research has found the reverse, that it is a risk factor without long-term benefit, used only for its short term effects.[16] However, research on nicotine as administered through a patch or gum is ongoing.

Nicotine has very powerful[specify] effects on arteries throughout the body. Nicotine is a stimulant, speeding up the heart by about 20 beats per minute with every cigarette; it raises blood pressure, and is a vasoconstrictor, making it harder for the heart to pump through the constricted arteries. It causes the body to release its stores of fat and cholesterol into the blood.

Nicotine increases the risk of blood clots significantly. [citation needed] If blood clots in an artery, blood flow is reduced or halted, and tissue loses its source of oxygen and nutrients and dies in minutes.

Peripheral circulation, arteries going to the extremities, are also highly susceptible to the vasoconstrictor effects of nicotine as well as the increased risk of clots and clogging.[citation needed]

Therapeutic uses

The primary therapeutic use of nicotine is in treating nicotine dependence in order to eliminate smoking with its risks to health. Controlled levels of nicotine are given to patients through gums, dermal patches, lozenges, or nasal sprays in an effort to wean them off their dependence.

However, in a few situations, smoking has been observed to apparently be of therapeutic value to patients. These are often referred to as "Smoker’s Paradoxes"[17]. Although in most cases the actual mechanism is understood only poorly or not at all, it is generally believed that the principal beneficial action is due to the nicotine administered, and that administration of nicotine without smoking may be as beneficial as smoking, without the higher risk to health due to tar and other ingredients found in tobacco.

For instance, recent studies suggest that smokers require less frequent repeated revascularization after percutaneous coronary intervention (PCI).[17] Risk of ulcerative colitis has been frequently shown to be reduced by smokers on a dose-dependent basis; the effect is eliminated if the individual stops smoking.[18][19] Smoking also appears to interfere with development of Kaposi's sarcoma,[20] breast cancer among women carrying the very high risk BRCA gene,[21] preeclampsia,[22] and atopic disorders such as allergic asthma.[23] A plausible mechanism of action in these cases may be nicotine acting as an anti-inflammatory agent, and interfering with the inflammation-related disease process, as nicotine has vasoconstrictive effects.[24]

With regard to neurological diseases, a large body of evidence suggests that the risks of Parkinson's disease or Alzheimer's disease might be twice as high for non-smokers than for smokers.[25] Many such papers regarding Alzheimer's disease[26] and Parkinson's Disease[27] have been published.

Recent studies have indicated that nicotine can be used to help adults suffering from Autosomal dominant nocturnal frontal lobe epilepsy. The same areas that cause seizures in that form of epilepsy are also responsible for processing nicotine in the brain.[28]

Nicotine and its metabolites are being researched for the treatment of a number of disorders, including ADHD and Parkinson's Disease. [29]

The therapeutic use of nicotine as a means of appetite-control and to promote weight loss is anecdotally supported by many ex-smokers who claim to put on weight after quitting. However studies of nicotine in mice [30] suggests it may play a role in weight-loss that is independent of appetite. And studies involving the elderly suggest that nicotine affects not only weight loss, but also prevents some weight gain. [31]

See also

References

  1. ^ "FDA-sourced list of all drugs with black box warnings (Use Download Full Results and View Query links.)". nctr-crs.fda.gov. FDA. Retrieved 22 Oct 2023.
  2. ^ "Smoking and Tobacco Control Monograph No. 9" (PDF).
  3. ^ American Heart Association and Nicotine addiction.
  4. ^ "Interindividual variability in the metabolism and cardiovascular effects of nicotine in man".
  5. ^ Human Anatomy and Physiology. Elaine N Marieb & Katja Hoehn. 2007, Pearson Education.
  6. ^ Fowler JS, Volkow ND, Wang GJ, Pappas N, Logan J, MacGregor R, Alexoff D, Wolf AP, Warner D, Cilento R, Zezulkova I (1998). "Neuropharmacological actions of cigarette smoke: brain monoamine oxidase B (MAO B) inhibition". Journal of addictive diseases. PMID 9549600.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. ^ Einstein, Stanley (1989). Drug and Alcohol Use: Issues and Factors. Springer. pp. 101–118. ISBN 0306413787.
  8. ^ http://www.nida.nih.gov/researchreports/nicotine/nicotine2.html
  9. ^ http://www.nida.nih.gov/NIDA_notes/NNvol19N2/Early.html
  10. ^ Nolley E.P. & Kelley B.M. "Adolescent reward system perseveration due to nicotine: Studies with methylphenidate.," Neurotoxicol Teratol., 2006 Oct 4
  11. ^ Okamoto M., Kita T., Okuda H., Tanaka T., Nakashima T. (1994). "Effects of aging on acute toxicity of nicotine in rats". Pharmacol Toxicol. 75 (1): 1–6.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. ^ IPCS INCHEM
  13. ^ Machaalani et al. (2005) "Effects of postnatal nicotine exposure on apoptotic markers in the developing piglet brain"
  14. ^ Schizophr. Res. 2002
  15. ^ Am. J. Psychiatry 1995
  16. ^ Br. J. Psychiatry 2005
  17. ^ a b Cohen, David J. (2001). "Impact of Smoking on Clinical and Angiographic Restenosis After Percutaneous Coronary Intervention". Circulation. 104: 773. Retrieved 2006-11-06. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  18. ^ Longmore, M., Wilkinson, I., Torok, E. Oxford Handbook of Clinical Medicine (Fifth Edition) p. 232
  19. ^ Green, JT (November, 2000). "Nitric oxide mediates a therapeutic effect of nicotine in ulcerative colitis". Aliment Pharmacol Ther. 14 (11): 1429–1434. PMID: 11069313. Retrieved 2006-11-06. {{cite journal}}: Check date values in: |date= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  20. ^ "Smoking Cuts Risk of Rare Cancer". UPI. March 29, 2001. Retrieved 2006-11-06. {{cite news}}: Cite has empty unknown parameter: |coauthors= (help)
  21. ^ Recer, Paul (May 19, 1998). "Cigarettes May Have an Up Side". AP. Retrieved 2006-11-06. {{cite news}}: Cite has empty unknown parameter: |coauthors= (help)
  22. ^ Lain, Kristine Y. (November 1991). "Urinary cotinine concentration confirms the reduced risk of preeclampsia with tobacco exposure". American Journal of Obstetrics and Gynecology. 181 (5): 908–14. PMID: 11422156. Retrieved 2006-11-06. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); line feed character in |coauthors= at position 79 (help)
  23. ^ Hjern, A (June 2001). "Does tobacco smoke prevent atopic disorders? A study of two generations of Swedish residents". Clin Exp Allergy. 31 (6): 908–914. PMID: 11422156. Retrieved 2006-11-06. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  24. ^ Lisa Melton (June 2006). "Body Blazes". Scientific American: p.24. {{cite journal}}: |pages= has extra text (help)
  25. ^ Fratiglioni, L (August 2000). "Smoking and Parkinson's and Alzheimer's disease: review of the epidemiological studies". Behav Brain Res. 113 (1–2): 117–120. PMID: 10942038. Retrieved 2006-11-06. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  26. ^ Thompson, Carol. "Alzheimer's disease is associated with non-smoking". Retrieved 2006-11-06. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  27. ^ Thompson, Carol. "Parkinson's disease is associated with non-smoking". Retrieved 2006-11-06. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  28. ^ "Nicotine as an antiepileptic agent in ADNFLE: An n-of-one study".
  29. ^ "Attention-Deficit Hyperactivity Disorder". Reuters Health. Reuters. 2001. Archived from the original on 2006-04-26. Nicotine improves ADHD symptoms. Although such findings should certainly not encourage anyone to smoke, some studies are focusing on benefits of nicotine therapy in adults with ADHD. {{cite web}}: Unknown parameter |month= ignored (help)
  30. ^ NIH, online at [1]
  31. ^ Cigarette Smoking and Weight Loss in Nursing Home Residents [2]

Further reading