HOME WEB NEWS IMAGES CLASSIFIEDS YELLOW PAGESPOLLS - SURVEYS WIKI COUNTRIES PHOTOS US UK INDIA
Cities Stocks Weather Movies Coupons Travel Blogs Health Horoscope Maps ASIA EUROPE Classifieds Yellow Pages
 stock market quote, stock market crash of 1929 - Shopping | ||
|
Endstream endobj, p?? 0??, public warehousing warehousing association, warehouse data depot data database downloads free spatial mapping arcinfo arcview mapinfo, warehoused | ||
|
Cabernet sauvignon, food coloring, petit verdot bourbon, alcohol, accessories | ||
|
This article is about the chemical compound. For other uses, see Nicotine (disambiguation).
| |
| |
| Nicotine | |
| Systematic (IUPAC) name | |
| (S)-3-(1-Methyl-2-pyrroli-
dinyl)pyridine | |
| Identifiers | |
| CAS number | |
| ATC code | N07 |
| PubChem | |
| Chemical data | |
| Formula | C10H14N2 |
| Mol. mass | 162.26 g/mole |
| Physical data | |
| Density | 1.01 g/cm³ |
| Melt. point | -79 °C (-110 °F) |
| Boiling point | 247 °C (477 °F) |
| Pharmacokinetic data | |
| Bioavailability | ? |
| Metabolism | ? |
| Half life | 2 hours |
| Excretion | ? |
| Therapeutic considerations | |
| Pregnancy cat. |
?(US) |
| Legal status | |
| Dependence Liability | Medium to high |
| Routes | Smoked (as tobacco), Insufflated (as snuff), Chewed |
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,Smoking and Tobacco Control Monograph No. 9. 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.American Heart Association and Nicotine addiction.
Contents |
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.
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.
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 hoursInterindividual variability in the metabolism and cardiovascular effects of nicotine in man.. 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.
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.
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 Human Anatomy and Physiology. Elaine N Marieb & Katja Hoehn. 2007, Pearson Education.
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]
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.
Studies have shown that smoking tobacco inhibits monoamine oxidase (MAO)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. , 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.
Furthermore, it 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.
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]
ResearchEinstein, Stanley (1989). Drug and Alcohol Use: Issues and Factors. Springer, 101-118. ISBN 0306413787. 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 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.
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. http://www.nida.nih.gov/researchreports/nicotine/nicotine2.html
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. Gorillas have been forced to smoke cigarettes by humans, and have similar difficulty quitting.http://www.nida.nih.gov/NIDA_notes/NNvol19N2/Early.html
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. Nolley E.P. & Kelley B.M. "Adolescent reward system perseveration due to nicotine: Studies with methylphenidate.," Neurotoxicol Teratol., 2006 Oct 4
There is significant anecdotal evidence from pharmacist vendors, via their customers, about addiction to nicotine gum or nicotine patches.
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.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. IPCS INCHEM 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).Machaalani et al. (2005) "Effects of postnatal nicotine exposure on apoptotic markers in the developing piglet brain"
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. Schizophr. Res. 2002 Am. J. Psychiatry 1995 More recent research has found the reverse, that it is a risk factor without long-term benefit, used only for its short term effects.Br. J. Psychiatry 2005 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]
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" Cohen, David J.; Michel Doucet, Donald E. Cutlip, Kalon K.L. Ho, Jeffrey J. Popma, Richard E. Kuntz (2001). "Impact of Smoking on Clinical and Angiographic Restenosis After Percutaneous Coronary Intervention". Circulation 104: 773. Retrieved on 2006-11-06. . 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). 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.Longmore, M., Wilkinson, I., Torok, E. Oxford Handbook of Clinical Medicine (Fifth Edition) p. 232 Green, JT; Richardson C, Marshall RW, Rhodes J, McKirdy HC, Thomas GA, Williams GT (November, 2000). "Nitric oxide mediates a therapeutic effect of nicotine in ulcerative colitis". Aliment Pharmacol Ther 14 (11): 1429-1434. PMID: 11069313. Retrieved on 2006-11-06. Smoking also appears to interfere with development of Kaposi\'s sarcoma, "Smoking Cuts Risk of Rare Cancer", UPI, March 29, 2001. Retrieved on 2006-11-06. (English) breast cancer among women carrying the very high risk BRCA gene, Recer, Paul. "Cigarettes May Have an Up Side", AP, May 19, 1998. Retrieved on 2006-11-06. (English) preeclampsia, Lain, Kristine Y.; Robert W. Powers, Marijane A. Krohn, Roberta B. Ness, William R. Crombleholme, James M. Roberts (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 on 2006-11-06. and atopic disorders such as allergic asthma. Hjern, A; Hedberg A, Haglund B, Rosen M (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 on 2006-11-06. 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.Lisa Melton (June 2006). "Body Blazes". Scientific American: p.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. Fratiglioni, L; Wang HX (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 on 2006-11-06. Many such papers regarding Alzheimer\'s disease Thompson, Carol. Alzheimer\'s disease is associated with non-smoking. Retrieved on 2006-11-06. and Parkinson\'s Disease Thompson, Carol. Parkinson\'s disease is associated with non-smoking. Retrieved on 2006-11-06. 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.Nicotine as an antiepileptic agent in ADNFLE: An n-of-one study.
Nicotine and its metabolites are being researched for the treatment of a number of disorders, including ADHD and Parkinson\'s Disease. Attention-Deficit Hyperactivity Disorder. Reuters Health. Reuters (December 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.”
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 NIH, online at [1] 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. Cigarette Smoking and Weight Loss in Nursing Home Residents
| Stimulants | |
|---|---|
| Eugeroics | Adrafinil • Armodafinil • Carphedon • Modafinil |
| Phenethylamines |
4-Fluoroamphetamine • 4-Fluoromethamphetamine • 4-Methylmethcathinone • 4-MTA • α-PPP • Aletamine • Amphechloral • Amphetamine (Dextroamphetamine, Adderall) • Amphetaminil • Benzphetamine • Bupropion • Cathinone • Chlorphentermine • Clobenzorex • Clortermine • Cypenamine • Diethylpropion • Dimethoxyamphetamine • Dimethylamphetamine • Dimethylcathinone • Ephedrine • Epinephrine • Ethcathinone • Ethylamphetamine • Fencamfamine • Fenethylline • Fenfluramine • Fenproporex • Feprosidnine • Furfenorex • Levomethamphetamine • Lisdexamfetamine • MDMA • Mefenorex • Methamphetamine • Methcathinone • Methoxyphedrine • Methylone • Octopamine • Parahydroxyamphetamine • PMA • PMEA • PMMA • PPAP • Phendimetrazine • Phenmetrazine • Phentermine • Phenylephrine • Phenylpropanolamine • Prolintane Propylamphetamine • Pseudoephedrine • Selegiline • Synephrine • Xylopropamine |
| Piperazines |
|
| Xanthines | Caffeine • Aminophylline • Paraxanthine • Theobromine • Theophylline |
| Tropanes |
Brasofensine • CFT • β-CIT • Cocaethylene • Cocaine • Dimethocaine • PIT • PTT • RTI-121 • Tesofensine • Troparil • WF-23 • WF-33 |
| Cholinergics | Arecoline • Cotinine • Nicotine |
| Convulsants | Bicuculline • Gabazine • Pentetrazol • Picrotoxin • Strychnine • Thujone |
| Phenylaminooxazoles |
4-Methyl-aminorex • Aminorex • Clominorex • Fenozolone • Fluminorex • Pemoline • Thozalinone |
| Others |
Amineptine • Bemegride • BPAP • Benzydamine • Clenbuterol • Clofenciclan • Cyclopentamine • Cyprodenate • Desoxypipradrol • Diphenyl prolinol • Ethylphenidate • Ethamivan • Gilutensin • GYKI-52895 • Hexacyclonate • Indanorex • Indatraline • Isometheptene • Mazindol • MDPV • Mesocarb • Methylphenidate (Dexmethylphenidate) • Naphthylisopropylamine • Nikethamide • Nocaine • Nomifensine • Phacetoperane • Phthalimidopropiophenone • Pipradrol • Prolintane • Propylhexedrine • Pyrovalerone • Sibutramine • Tuamine • Vanoxerine • Yohimbine • Zylofuramine |
| See also Sympathomimetic amines | |
| Drugs used in addictive disorders (N07B) | |
|---|---|
| Nicotine dependence | Nicotine - Bupropion - Varenicline - Mecamylamine - Clonidine |
| Alcohol dependence | Disulfiram - Calcium carbimide - Acamprosate - Naltrexone - Nalmefene - Topiramate - Clonidine |
| Opioid dependence | Buprenorphine - Methadone - Levacetylmethadol - Heroin - Fentanyl - Dihydrocodeine - Dihydroetorphine - Clonidine - Lofexidine - Naltrexone - Ibogaine - 18-Methoxycoronaridine - Morphine - MS-Contin |
| Stimulant dependence | Dexamphetamine - Bupropion - Vanoxerine - Nocaine |
| Benzodiazepine dependence | Clonidine - Diazepam - Phenytoin - Phenobarbital |
| Cocaine dependence | Bupropion - Vanoxerine - Nocaine - Baclofen |
This article is licensed under the GNU Free Documentation License. It uses material from Wikipedia
