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{{Drugbox|
{{Details0|Atropine (Injection)}}
|IUPAC_name = (8-methyl-8-azabicyclo[3.2.1]oct-3-yl) 3-hydroxy-2-phenylpropanoate
{{Details0|Atropine (ophthalmic)}}
| image=Atropine_svg.png
| image2=Atropine3d.png
| width=180px
| CAS_number=51-55-8
| ATC_prefix=A03
| ATC_suffix=BA01
| ATC_supplemental={{ATC|S01|FA01}}
| PubChem=174174
| DrugBank=APRD00807
| C = 17 | H = 23 | N = 1 | O = 3
| molecular_weight = 289.369
| bioavailability= 25%
| metabolism = 50% [[hydrolyse]]d to [[tropine]] and tropic acid
| elimination_half-life= 2 hours
| excretion = 50% excreted unchanged in urine
| pregnancy_US = C
| legal_status = R<sub>x</sub> only
| routes_of_administration= Oral, [[Intravenous therapy|IV]], rectal
}}
 
{{CMG}}
 
{{Editor Join}}
 
'''Atropine''' is a [[tropane]] [[alkaloid]] extracted from the [[deadly nightshade]] (''Atropa belladonna'') and other plants of the family [[Solanaceae]]. It is a [[secondary metabolite]] of these plants and serves as a [[hard drug|drug]] with a wide variety of effects.  Being potentially deadly, it derives its name from Atropos, one of the three Fates who, according to Greek mythology, chose how a person was to die.
 
== Physiological effects and uses ==
Generally, atropine lowers the "rest and digest" activity of all [[muscle]]s and [[gland]]s regulated by the [[parasympathetic nervous system]]. This occurs because atropine is a [[competitive antagonist]] of the muscarinic [[acetylcholine receptor]]s. ([[Acetylcholine]] is the main [[neurotransmitter]] used by the [[parasympathetic]] nervous system.) Therefore, it may cause swallowing difficulties and reduced secretions.
 
=== Ophthalmic use ===
[[Topical]] atropine is used as a [[cycloplegic]], to temporarily paralyze the [[accommodation reflex]]; and as a [[mydriatic]], to dilate the [[pupil]]s. Atropine degrades slowly, typically wearing off in 2 to 3 days, so [[tropicamide]] (a shorter-acting cholinergic antagonist) or [[phenylephrine]] (an α-adrenergic agonist) are generally preferred as mydriatics. The effects of atropine can last up to two weeks. Atropine induces [[mydriasis]] by blocking contraction of the circular [[pupillary sphincter]] muscle, which is normally stimulated by acetylcholine release, thereby allowing the radial [[pupillary dilator]] muscle to contract and dilate the pupil. Atropine is contraindicated in patients predisposed to narrow angle [[glaucoma]].
 
Atropine can be given to patients who have direct globe trauma.
 
=== Resuscitation ===
Injections of atropine are used in the treatment of [[bradycardia]] (an extremely low heart rate), [[asystole]] and [[pulseless electrical activity]] (PEA) in [[cardiac arrest]]. This works because the main action of the [[vagus nerve]] of the parasympathetic system on the heart is to slow it down. Atropine blocks that action and therefore may speed up the heart rate. The usual dose of atropine is 0.5 to 1&nbsp;mg every three to five minutes, up to a maximum dose of 3&nbsp;mg.
 
Atropine is also useful in treating [[First degree AV block |first degree heart block]], [[Second degree AV block#Type 1 Second degree AV block|second degree heart block Mobitz Type 1 (Wenckebach block)]], and also [[Third degree AV block|third degree heart block]] with a high [[Purkinje fibers|Purkinje]] or [[Atrioventricular node|AV-nodal]] escape rhythm.  It is usually not effective in [[Second degree AV block#Type 2 Second degree AV block|second degree heart block Mobitz type 2]], and in third degree heart block with a low Purkinje or ventricular escape rhythm. Atropine is contraindicated in ischemia-induced conduction block, because the drug increases oxygen demand of the AV nodal tissue, thereby aggravating ischemia and the resulting heart block.
 
One of the main actions of the [[parasympathetic nervous system]] is to stimulate the [[Muscarinic acetylcholine receptor#Comparison of types|M<sub>2</sub>]] [[muscarinic acetylcholine receptor|muscarinic receptor]] in the heart, but atropine inhibits this action.
 
=== Secretions and bronchoconstriction ===
Atropine's actions on the parasympathetic nervous system inhibits salivary, sweat, and mucus glands.  This can be useful in treating [[Hyperhidrosis]] and can prevent the [[death rattle]] of dying patients.  Even though it has not been officially indicated for either of these purposes by the FDA, it has been used by physicians for these purposes. <ref>http://www.eperc.mcw.edu/fastFact/ff_109.htm</ref>
 
=== Antidote for organophosphate poisoning ===
By blocking the action of [[acetylcholine]] at [[muscarinic]] receptors, atropine also serves as an antidote for poisoning by [[organophosphate]] [[insecticide]]s and [[nerve gas]]es. Troops who are likely to be attacked with chemical weapons often carry [[autoinjector]]s with atropine and [[obidoxime]] which can be quickly injected into the thigh. It is often used in conjunction with [[Pralidoxime chloride]].
 
Atropine is given as an antidote to SLUDGE ([[Salivation]], [[Lacrimation]], [[Urination]], [[Diaphoresis]], [[Gastrointestinal]] motility, [[Emesis]]) symptoms caused by organophosphate poisoning. 
 
Some of the nerve gases attack and destroy [[acetylcholinesterase]], so the action of acetylcholine becomes prolonged. Therefore, atropine can be used to reduce the effect of acetylcholine.
 
=== Side effects and overdose ===
Adverse reactions to atropine include ventricular [[fibrillation]], supraventricular or ventricular [[tachycardia]], [[Vertigo (medical)|dizziness]], [[nausea]], blurred vision, loss of balance, dilated pupils, [[photophobia]], and possibly, notably in the elderly, extreme [[confusion]], [[hallucination]]s, and excitation.  These latter effects are due to the fact that atropine is able to cross the [[blood-brain barrier]]. Because of the [[Psychedelics, dissociatives and deliriants|hallucinogenic]] properties, some have used the drug [[Recreational drug use|recreationally]], though this is very dangerous and often unpleasant.
 
In overdoses, atropine is [[poison]]ous. Atropine is sometimes added to other potentially addictive drugs; abuse of those drugs is then prevented by the unpleasant effects of atropine overdose.{{Fact|date=February 2007}}
 
Although atropine treats [[bradycardia]] (slow heart rate) in emergency settings, it can cause heart rate slowing when given at very low doses, presumably as a result of a weak [[partial agonist]] effect at the cardiac muscarinic receptors.{{Fact|date=February 2007}}
 
The antidote to atropine is [[physostigmine]] or [[pilocarpine]].
 
A commonly used [[mnemonic]] used to described the physiologic manifestions of atropine overdose is:  "hot as a hare, blind as a bat, dry as a bone, red as a beet, and mad as a wet hen".<ref name="holzman">{{cite web|url=http://www.anesthesiology.org/pt/re/anes/fulltext.00000542-199807000-00030.htm;jsessionid=GSJKLv9vLCdQSmpp6vH3xdhnzWN1hy3s7JqMNFpWkHhLbKJT5vLM!741375937!-949856145!8091!-1#P89|title=The Legacy of Atropos|author=Robert S. Holzman, MD|journal=Anesthesiology|volume=89|issue=1|date=1998-07|pages=241-249}} citing J. Arena, Poisoning: Toxicology-Symptoms-Treatments, 3rd edition. Springfield, Charles C. Thomas, 1974, p 345 </ref> This set of symptoms is known as [[toxidrome#Anticholinergic toxidrome|anticholinergic toxidrome]], and may also be caused by other drugs with anticholinergic effects, such as [[diphenhydramine]], [[phenothiazine]] [[antipsychotic]]s and [[benztropine]].<ref>{{cite web | url = http://www.intox.org/databank/documents/treat/treate/trt05_e.htm | title = Acute anticholinergic syndrome | author = Szajewski J | year = 1995 | publisher = IPCS Intox Databank}}</ref>
 
== Chemistry and pharmacology==
Atropine is a [[racemic]] mixture of D-[[hyoscyamine]] and L-hyoscyamine, with most of its physiological effects due to L-hyoscyamine. Its pharmacological effects are due to binding to muscarinic [[acetylcholine receptor]]s. It is an antimuscarinic agent.
 
The most common atropine compound used in medicine is atropine [[sulfate]] ([[carbon|C]]<sub>17</sub>[[hydrogen|H]]<sub>23</sub>[[Nitrogen|N]][[Oxygen|O]]<sub>3</sub>)<sub>2</sub>·[[sulfate|H<sub>2</sub>SO<sub>4</sub>]]·[[water|H<sub>2</sub>O]], the full chemical name is 1α H, 5α H-Tropan-3-α ol (±)-tropate(ester), sulfate monohydrate.
 
== History ==
''Mandragora'' (mandrake) was described by Theophrastus in the fourth century B.C. for treatment of wounds, gout, and sleeplessness, and as a love potion.  By the first century A.D. [[Dioscorides]] recognized wine of mandrake as an [[anaesthetic]] for treatment of pain or sleeplessness, to be given prior to surgery or cautery.<ref name="holzman" />  The use of [[Solanaceae]] containing [[tropane]] alkaloids for anaesthesia, often in combination with [[opium]], persisted throughout the Roman and Islamic Empires and continued in Europe until superseded by the use of [[ether]], [[chloroform]], and other modern anaesthetics.
 
Atropine extracts from the Egyptian henbane were used by Cleopatra in the last century B.C. to dilate her [[pupils]], in the hope that she would appear more alluring.  In the Renaissance, women used the juice of the berries of ''[[Atropa belladonna]]'' to enlarge the pupils of their eyes, for cosmetic reasons; "bella donna" is Italian for "beautiful lady".
 
The mydriatic effects of atropine were studied among others by the German [[chemistry|chemist]] Friedrich Ferdinand Runge (1795–1867). In 1831 the pharmacist Mein succeeded the pure crystalline isolation of atropine. The substance was first synthesized by German chemist [[Richard Willstätter]] in 1901.
 
== Natural sources ==
Atropine is found in many members of the Solanaceae family. The most commonly found sources are ''[[Atropa belladonna]]'', ''[[Datura inoxia]]'', ''[[Datura metel|D. metel]]'', and ''[[Datura stramonium|D. stramonium]]''. Other sources include members of the ''[[Brugmansia]]'' and ''Hyoscyamus'' genera. The ''[[Nicotiana]]'' genus (including the tobacco plant, ''[[Nicotiana tabacum|N. tabacum]]'') is also found in the Solanaceae family, but these plants do not contain atropine or other [[tropane]] alkaloids.
 
==See also==
*[[Mark I NAAK]]
 
==References==
<references />
 
{{Drugs for functional gastrointestinal disorders}}
{{Mydriatics and cycloplegics}}
{{Deliriants}}
{{Emergency medicine}}
 
[[Category:Natural tropane alkaloids]]
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[[Category:Deliriants]]
[[Category:Muscarinic antagonists]]
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Latest revision as of 19:53, 7 May 2015