関: spe- cific agents

WordNet

a drug that neutralizes or counteracts the effects of another drug
a muscle that relaxes while another contracts; "when bending the elbow the triceps are the antagonist"
a cellular structure that is postulated to exist in order to mediate between a chemical agent that acts on nervous tissue and the physiological response

PrepTutorEJDIC

対立する人,敵対者,競争相手(opponent)
=sense organ / 受信装置

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/05/22 11:40:08」(JST)

wiki en

A muscarinic receptor antagonist (MRA) is an agent that blocks the activity of the muscarinic acetylcholine receptor. Acetylcholine (often abbreviated ACh) is a neurotransmitter, whose receptor is a protein found in synapses and other cell membranes. Besides responding to their primary neurochemical, neurotransmitter receptors can be sensitive to a variety of other molecules. Acetylcholine receptors are classified into two groups based on this:

muscarinic, which respond to muscarine
nicotinic, which respond to nicotine

Most muscarinic receptor antagonists are synthetic chemicals; however, the two most commonly used anticholinergics, scopolamine and atropine, are belladonna alkaloids, and are naturally extracted.

Effects

Scopolamine and atropine have similar effects on the peripheral nervous system. However, scopolamine has greater effects on the Central Nervous System (CNS) than atropine due to its ability to cross the blood–brain barrier. At higher-than-therapeutic doses, atropine and scopolamine cause CNS depression characterized by amnesia, fatigue, and reduction in rapid eye movement sleep. Scopolamine (Hyoscine) has anti-emetic activity and is, therefore, used to treat motion sickness.

Antimuscarinics are also used as anti-parkinsonian drugs. In Parkinsonism, there is imbalance between levels of acetylcholine and dopamine in the brain, involving both increased levels of acetylcholine and degeneration of dopaminergic pathways (nigrostriatal pathway). Thus, in Parkinsonism there is decreased level of dopaminergic activity. One method of balancing the neurotransmitters is through blocking central cholinergic activity using muscarinic receptor antagonists. In addition to increased activity to dopaminergic neurons from anticholinergics, antagonists of the muscarinic-acetylcholine receptors produce a sense of happiness and euphoria. This led to the discovery of various tricyclic antidepressants

Atropine acts on the M2 receptors of the heart and antagonizes the activity of acetylcholine. It causes tachycardia by blocking vagal effects on the sinoatrial node. Acetylcholine hyperpolarizes the sinoatrial node, which is overcome by MRA and thus increases the heart rate. If atropine is given by intramuscular or subcutaneous injection, it causes initial bradycardia. This is because by i.m/s.c it acts on presynaptic M1 receptors (autoreceptors). Intake of acetylcholine in axoplasm is prevented and the presynaptic nerve releases more acetylcholine into the synapse that initially causes bradycardia.

In the atrioventricular node, the resting potential is abbreviated, which facilitates conduction. This is seen as a shortened PR-interval on an electrocardiogram.

It has an opposite effect on blood pressure. Tachycardia and stimulation of the vasomotor center causes an increase in blood pressure. But, due to feed back regulation of the vasomotor center, there is fall in blood pressure due to vasodilation.

Important^[1] muscarinic antagonists include atropine, Hyoscyamine, hyoscine, ipratropium, tropicamide, cyclopentolate, and pirenzepine.

Muscarinic antagonists such as ipratropium bromide can also be effective in treating asthma, since acetylcholine is known to cause smooth muscle contraction, especially in the bronchi.

Comparison table

Substance	Trade names	Mechanism	Clinical use	Adverse effects
Atropine (D/L-Hyoscyamine)	Symax, HyoMax, Anaspaz, Egazil, Buwecon, Cystospaz, Levsin, Levbid, Levsinex, Donnamar, NuLev, Spacol T/S and Neoquess	non-selective antagonism, CNS depression^[1]	in anaesthesia^[1]^[2] anticholinesterase poisoning^[1] bradycardia^[1] antispasmodic in gastrointestinal hypermotility^[1]	urinary retention^[1] xerostomia^[1] blurred vision^[1]
Scopolamine (L-Hyoscine)	Scopace, Transderm-Scop, Maldemar, Buscopan	non-selective antagonism, CNS depression^[1]	as atropine^[1] motion sickness^[1]	as atropine^[1] sedation^[1]
Hydroxyzine	Vistaril, Atarax
Ipratropium	Atrovent and Apovent	non-selective antagonism, without any mucociliary excretion inhibition.^[1]	in asthma and bronchitis^[1]
Tropicamide		short acting non-selective antagonism, CNS depression^[1]	produce mydriasis and cycloplegia in diagnostics^[1]	may cause ocular hypertension^[1]
Pirenzepine		M1 receptor-selective antagonist^[1] inhibits gastric secretion^[1]	in peptic ulcer (not much anymore)^[1]	(fewer than non-selective ones)^[1]
Diphenhydramine	Benadryl, Nytol	Non-selective antagonism in the central nervous system, blood vessels and smooth muscle tissues	for extrapyramidal symptoms from typical and atypical antipsychotic medications antihistamine sleep aid antiparkinson agent management of asthma symptoms	*Sedation, dry mouth, constipation, urinary retention
Dimenhydrinate	Dramamine	Combination of diphenhydramine with a methylxanthine salt	motion sickness
Dicyclomine			Irritable bowel syndrome
Flavoxate	Urispas		Urinary bladder antispasmodic
Oxybutynin	Ditropan		overactive bladder urge incontinence
Tiotropium	Spiriva		Chronic obstructive pulmonary disease
Cyclopentolate		short acting non-selective antagonism, CNS depression^[1]	produce mydriasis and cycloplegia in diagnostics^[1]	may cause ocular hypertension^[1]
Atropine methonitrate		non-selective antagonism, blocks transmission in ganglia.^[1] Lacks CNS effects^[3]	antispasmodic in gastrointestinal hypermotility^[1]
Trihexyphenidyl/Benzhexol	Artane	Targets the M1 Muscarinic receptor	Parkinson's disease	Drug at relative dose has 83% activity of atropine, thus has the same side-effects
Tolterodine	Detrusitol, Detrol
Solifenacin	Vesicare	Competitive muscarinic acetylcholine receptor antagonist	overactive bladder (OAB) Urgency (urge incontinence)
Darifenacin	Enablex	Selective for M3 receptors ^[3]	Urinary incontinence ^[3]	Few side effects^[3]
Benzatropine	Cogentin	Reduces the effects of the relative central cholinergic excess that occurs as a result of dopamine deficiency.	Parkinson's disease
Mebeverine	Colofac, Duspatal, Duspatalin	A muscolotropic spasmolytic with a strong and selective action on the smooth muscle spasm of the gastrointestinal tract, in particular of the colon.	Irritable bowel syndrome in its primary form (e.g., Abdominal Pain, Bloating, Constipation, and Diarrhea). Irritable bowel syndrome associated with organic lesions of the gastrointestinal tract. (e.g., diverticulosis & diverticulitis, etc.).	skin rashes
Procyclidine		Antimuscarinic	Drug-induced parkinsonism, akathisia and acute dystonia Parkinson disease Idiopathic or secondary dystonia	Overdose produces confusion, agitation and sleeplessness that can last up to or more than 24 hours. Pupils become dilated and unreactive to light. Tachycardia (fast heart beat), as well as auditory and visual hallucinations
Aclidinium bromide	Tudorza	Selective long acting muscarinic antagonist	Bronchospasm Chronic Obstructive Pulmonary Disease

References

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t ^u ^v ^w ^x ^y ^z ^aa ^ab Rang, H. P. (2003). Pharmacology. Edinburgh: Churchill Livingstone. ISBN 0-443-07145-4. Page 147
^ Mirakhur, RK (August 1991). "Preanaesthetic medication: a survey of current usage". Journal of the Royal Society of Medicine 84 (8): 481–483. PMC 1293378. PMID 1886116.
^ ^a ^b ^c ^d Table 10-5 in: Rod Flower; Humphrey P. Rang; Maureen M. Dale; Ritter, James M. (2007). Rang & Dale's pharmacology. Edinburgh: Churchill Livingstone. ISBN 0-443-06911-5.

External links

Effects of Muscarinic Antagonist
Atropine (Muscarinic Receptor Antagonist), Cardiovascular Pharmacology Concepts, Richard E. Klabunde, PhD
Muscarinic antagonists at the US National Library of Medicine Medical Subject Headings (MeSH)
MeSH list of agents 82018727

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English Journal

The context preexposure facilitation effect in mice: A dose-response analysis of pretraining scopolamine administration.

Brown KL, Kennard JA, Sherer DJ, Comalli DM, Woodruff-Pak DS.SourceDepartment of Psychology, Temple University, 1701 North 13th Street/Weiss Hall, Philadelphia, PA 19122, United States.
Behavioural brain research.Behav Brain Res.2011 Nov 20;225(1):290-6. Epub 2011 Jul 30.
The context preexposure facilitation effect (CPFE) is an elaboration of contextual fear conditioning and refers to enhanced contextual conditioning resulting from preexposure to the context prior to a separate, brief context-shock episode. A version of the CPFE developed by Rudy and colleagues in ra
PMID 21827794

Impairment of acetylcholine-mediated endothelium-dependent relaxation in isolated parotid artery of the alloxan-induced diabetic rabbit.

Roganovi? J, Radenkovi? M, Tani? N, Tani? N, Petrovi? N, Stoji? D.SourceDepartment of Pharmacology, Faculty of Dentistry, University of Belgrade, Belgrade Department of Clinical Pharmacology, Pharmacology and Toxicology, Medical Faculty, University of Belgrade, Belgrade Department of Neurobiology, Institute for Biological Research 'Sini?a Stankovi?', University of Belgrade, Belgrade Department of Radiobiology and Molecular Genetics, Institute of Nuclear Sciences 'Vin?a', Belgrade, Serbia.
European journal of oral sciences.Eur J Oral Sci.2011 Oct;119(5):352-60. doi: 10.1111/j.1600-0722.2011.00851.x.
Roganovi? J, Radenkovi? M, Tani? N, Tani? N, Petrovi? N, Stoji? D. Impairment of acetylcholine-mediated endothelium-dependent relaxation in isolated parotid artery of the alloxan-induced diabetic rabbit. Eur J Oral Sci 2011; 119: 352-360. c 2011 Eur J Oral Sci The aim of this study was to ass
PMID 21896051

Japanese Journal

Selective M3 Muscarinic Receptor Antagonist Inhibits Small-Cell Lung Carcinoma Growth in a Mouse Orthotopic Xenograft Model

Ami Nozomi,Koga Kazumi,Fushiki Hiroshi,Ueno Yoko,Ogino Yoshio,Ohta Hisashi
Journal of Pharmacological Sciences 116(1), 81-88, 2011
… In small cell lung carcinoma (SCLC), acetylcholine (ACh) is synthesized and secreted, and it acts as an autocrine growth factor through activation of its receptors, muscarinic receptor (mAChR) and nicotinic receptor (nAChR). … We used a highly selective M3 muscarinic antagonist, N-(2-[3-([3R]-1-(cyclohexylmethyl)-3-piperidinyl]methylamino)-3-oxopropyl]amino-2-oxoethyl)-3,3,3-triphenyl-propioamide (J-115311). …
NAID 130000663531

明期ラット海馬スライスにおいてカルバコール誘導β振動は出にくくなる(一般,ニューロコンピューティングの実装とシステム化,一般)

中司弘樹,夏目季代久
電子情報通信学会技術研究報告. NC, ニューロコンピューティング 110(246), 1-4, 2010-10-16
脳にはサーカディアンリズムがあり、そのリズムは神経活動に影響を及ぼしている。アセチルコリン作動薬であるカルバコールは海馬スライスにてβ振動を断続的に誘導する。本研究では、カルバコール誘導β振動が明期と暗期で異なる誘導のされ方を示すのかどうかを明らかにする。実際には、明期、暗期のラットから切り出した海馬スライスにカルバコールを投与しβ振動を誘導した。周波数、持続時間、振幅は、明期と暗期とで有意な差は …
NAID 110008106473

「ムスカリン受容体拮抗薬」

Muscarinic-Acetylcholine receptor antagonist
	Drug class
	Skeletal structor formula of Scopolamine, a nonselective antagonist of the muscarinic receptors
Use	Allergies, Asthma, Bradycardia, Motion sickness, Parkinson's disease, etc.
Biological target	Metabotropic acetylcholinergic receptors.
ATC code	V
External links
MeSH	D018727

　　[★]

英: muscarinic receptor antagonist
同: ムスカリン受容体遮断薬、抗ムスカリン様作用薬、antimuscarinic drug
関: ムスカリン受容体、アセチルコリン受容体

ベラドンナアルカロイド

気道閉塞性障害

イプラトロピウム ipratropium

散瞳薬

鎮痙薬

臭化ブチルスコポラミン scopolamine butylbromide

製品名：ブスコパン Buscopan

チキジウム tiquizium

抗潰瘍薬

パーキンソン病治療薬

「muscarinic antagonist」

　　[★]

ムスカリン受容体遮断薬、ムスカリン受容体拮抗薬、ムスカリン遮断薬、ムスカリン拮抗薬、ムスカリンアンタゴニスト、抗コリン薬

関: anticholinergic、anticholinergic agent、anticholinergic drug、anticholinergics、cholinergic antagonist、cholinolytic、cholinolytic drug、muscarinic receptor antagonist

「ムスカリン受容体遮断薬」

　　[★]

英: muscarinic receptor antagonist、muscarinic antagonist
関: 抗コリン薬、ムスカリン受容体拮抗薬、ムスカリン拮抗薬、ムスカリンアンタゴニスト、ムスカリン遮断薬

「muscarinic」

　　[★]

adj.

ムスカリン性の、ムスカリンの

n.

ムスカリン作用薬

関: cholinergic、cholinergic agent、cholinergic drug、cholinomimetic、muscarine、muscarinic agent、muscarinic agonist

[Rang147-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t ^u ^v ^w ^x ^y ^z ^aa ^ab Rang, H. P. (2003). Pharmacology. Edinburgh: Churchill Livingstone. ISBN 0-443-07145-4. Page 147

[Mirakhur-2] Mirakhur, RK (August 1991). "Preanaesthetic medication: a survey of current usage". Journal of the Royal Society of Medicine 84 (8): 481–483. PMC 1293378. PMID 1886116.

[Rang.26Dale6th10-5-3] Table 10-5 in: Rod Flower; Humphrey P. Rang; Maureen M. Dale; Ritter, James M. (2007). Rang & Dale's pharmacology. Edinburgh: Churchill Livingstone. ISBN 0-443-06911-5.

リンク元	「ムスカリン受容体拮抗薬」「muscarinic antagonist」「ムスカリン受容体遮断薬」
関連記事	「muscarinic」

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案内

muscarinic receptor antagonist