Methacholine
Methacholine (Provocholine) is a synthetic choline ester that acts as a non-selective muscarinic receptor agonist in the parasympathetic nervous system.
Uses
Methacholine is primarily used to diagnose bronchial hyperreactivity,[1] which is the hallmark of asthma and also occurs in chronic obstructive pulmonary disease. This is accomplished through the bronchial challenge test, or methacholine challenge, in which a subject inhales aerosolized methacholine, leading to bronchoconstriction. Other therapeutic uses are limited by its adverse cardiovascular effects, such as bradycardia and hypotension, which arise from its function as a cholinomimetic.
Pharmacology
It is highly active at all of the muscarinic receptors, but has little effect on the nicotinic receptors. Methacholine has a charged quaternary amine structure, rendering it insoluble to lipid cell membranes. Clinically, this means that it will not cross the blood-brain barrier and has poor absorption from the gastrointestinal tract. It is broken down at a relatively slow rate within the body, due to its resistance to acetylcholinesterases.
Methacholine has a β-methyl group which provides selectivity towards M-type receptors as compared to N-type receptors. The quaternary ammonium group is essential for activity. The ester however makes it susceptible to the enzyme acetylcholine esterase.[2]
Contraindications
Use of methacholine, is contraindicated in patients with recent heart attack or stroke, uncontrolled hypertension, known severe airway disease, or an aortic aneurysm. It may be used with caution by nursing or pregnant mothers and patients taking certain medications for myasthenia gravis.[3]
References
External links
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Agonists: 77-LH-28-1 • AC-42 • AC-260,584 • Aceclidine • Acetylcholine • AF30 • AF150(S) • AF267B • AFDX-384 • Alvameline • AQRA-741 • Arecoline • Bethanechol • Butyrylcholine • Carbachol • CDD-0034 • CDD-0078 • CDD-0097 • CDD-0098 • CDD-0102 • Cevimeline • cis-Dioxolane • Ethoxysebacylcholine • LY-593,039 • L-689,660 • LY-2,033,298 • McNA343 • Methacholine • Milameline • Muscarine • NGX-267 • Ocvimeline • Oxotremorine • PD-151,832 • Pilocarpine • RS86 • Sabcomeline • SDZ 210-086 • Sebacylcholine • Suberylcholine • Talsaclidine • Tazomeline • Thiopilocarpine • Vedaclidine • VU-0029767 • VU-0090157 • VU-0152099 • VU-0152100 • VU-0238429 • WAY-132,983 • Xanomeline • YM-796
Antagonists: 3-Quinuclidinyl Benzilate • 4-DAMP • Aclidinium Bromide • Anisodamine • Anisodine • Atropine • Atropine Methonitrate • Benactyzine • Benzatropine (Benztropine) • Benzydamine • BIBN 99 • Biperiden • Bornaprine • CAR-226,086 • CAR-301,060 • CAR-302,196 • CAR-302,282 • CAR-302,368 • CAR-302,537 • CAR-302,668 • CS-27349 • Cyclobenzaprine • Cyclopentolate • Darifenacin • DAU-5884 • Dimethindene • Dexetimide • DIBD • Dicyclomine (Dicycloverine) • Ditran • EA-3167 • EA-3443 • EA-3580 • EA-3834 • Elemicin • Etanautine • Etybenzatropine (Ethylbenztropine) • Flavoxate • Himbacine • HL-031,120 • Ipratropium bromide • J-104,129 • Hyoscyamine • Mamba Toxin 3 • Mamba Toxin 7 • Mazaticol • Mebeverine • Methoctramine • Metixene • Myristicin • N-Ethyl-3-Piperidyl Benzilate • N-Methyl-3-Piperidyl Benzilate • Orphenadrine • Otenzepad • Oxybutynin • PBID • PD-102,807 • PD-0298029 • Phenglutarimide • Phenyltoloxamine • Pirenzepine • Piroheptine • Procyclidine • Profenamine • RU-47,213 • SCH-57,790 • SCH-72,788 • SCH-217,443 • Scopolamine (Hyoscine) • Solifenacin • Telenzepine • Tiotropium bromide • Tolterodine • Trihexyphenidyl • Tripitamine • Tropatepine • Tropicamide • WIN-2299 • Xanomeline • Zamifenacin; Others: 1st Generation Antihistamines ( Brompheniramine, chlorphenamine, cyproheptadine, dimenhydrinate, diphenhydramine, doxylamine, mepyramine/ pyrilamine, phenindamine, pheniramine, tripelennamine, triprolidine, etc) • Tricyclic Antidepressants ( Amitriptyline, doxepin, trimipramine, etc) • Tetracyclic Antidepressants ( Amoxapine, maprotiline, etc) • Typical Antipsychotics ( Chlorpromazine, thioridazine, etc) • Atypical Antipsychotics ( Clozapine, olanzapine, quetiapine, etc)
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Agonists: 5-HIAA • A-84,543 • A-366,833 • A-582,941 • A-867,744 • ABT-202 • ABT-418 • ABT-560 • ABT-894 • Acetylcholine • Altinicline • Anabasine • Anatoxin-a • AR-R17779 • Butyrylcholine • Carbachol • Cotinine • Cytisine • Decamethonium • Desformylflustrabromine • Dianicline • Dimethylphenylpiperazinium • Epibatidine • Epiboxidine • Ethanol • Ethoxysebacylcholine • EVP-4473 • EVP-6124 • Galantamine • GTS-21 • Ispronicline • Lobeline • MEM-63,908 (RG-3487) • Nicotine • NS-1738 • PHA-543,613 • PHA-709,829 • PNU-120,596 • PNU-282,987 • Pozanicline • Rivanicline • Sazetidine A • Sebacylcholine • SIB-1508Y • SIB-1553A • SSR-180,711 • Suberylcholine • TC-1698 • TC-1734 • TC-1827 • TC-2216 • TC-5214 • TC-5619 • TC-6683 • Tebanicline • Tropisetron • UB-165 • Varenicline • WAY-317,538 • XY-4083
Antagonists: 18-Methoxycoronaridine • α-Bungarotoxin • α-Conotoxin • Alcuronium • Amantadine • Anatruxonium • Atracurium • Bupropion (Amfebutamone) • Chandonium • Chlorisondamine • Cisatracurium • Coclaurine • Coronaridine • Dacuronium • Decamethonium • Dextromethorphan • Dextropropoxyphene • Dextrorphan • Diadonium • DHβE • Dimethyltubocurarine (Metocurine) • Dipyrandium • Dizocilpine (MK-801) • Doxacurium • Duador • Esketamine • Fazadinium • Gallamine • Hexafluronium • Hexamethonium (Benzohexonium) • Ibogaine • Isoflurane • Ketamine • Kynurenic acid • Laudexium (Laudolissin) • Levacetylmethadol • Malouetine • Mecamylamine • Memantine • Methadone • Methorphan (Racemethorphan) • Methyllycaconitine • Metocurine • Mivacurium • Morphanol (Racemorphanol) • Neramexane • Nitrous Oxide • Pancuronium • Pempidine • Pentamine • Pentolinium • Phencyclidine • Pipecuronium • Radafaxine • Rapacuronium • Rocuronium • Surugatoxin • Suxamethonium (Succinylcholine) • Thiocolchicoside • Toxiferine • Trimethaphan • Tropeinium • Tubocurarine • Vecuronium • Xenon
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1-(-Benzoylethyl)pyridinium • 2-(α-Naphthoyl)ethyltrimethylammonium • 3-Chloro-4-stillbazole • 4-(1-Naphthylvinyl)pyridine • Acetylseco hemicholinium-3 • Acryloylcholine • AF64A • B115 • BETA • CM-54,903 • N,N-Dimethylaminoethylacrylate • N,N-Dimethylaminoethylchloroacetate
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Cymserine * Many of the acetylcholinesterase inhibitors listed above act as butyrylcholinesterase inhibitors.
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