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Muscarinic antagonist

A muscarinic receptor antagonist is an agent that reduces the activity of the muscarinic acetylcholine receptor. Most of them are synthetic, but scopolamine atropine are belladonna alkaloids, and are naturally extracted.

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

Comparison table

Substance	Trade names	Mechanism^[2]	Clinical use^[2]	Adverse effects^[2]
Atropine (D/L-Hyoscyamine)		non-selective antagonism, CNS stimulation	in anaesthesia anticholinesterase poisoning bradycardia antispasmodic in gastrointestinal hypermotility	urinary retention xerostomia blurred vision
Scopolamine (L-Hyoscine)		non-selective antagonism, CNS depression	as atropine motion sickness	as atropine sedation
Ipratropium		non-selective antagonism, without any mucociliary excretion inhibition.	in asthma and bronchitis
Tropicamide		short acting non-selective antagonism, CNS depression	produce mydriasis and cycloplegia in diagnostics	may cause ocular hypertension
Pirenzepine		M1 receptor-selective antagonist inhibits gastric secretion	in peptic ulcer (not much anymore)	(fewer than non-selective ones)
Diphenhydramine	Benadryl
Dimenhydrinate	Dramamine
dicyclomine
flavoxate
oxybutynin
tiotropium	Spiriva
cyclopentolate		short acting non-selective antagonism, CNS depression	produce mydriasis and cycloplegia in diagnostics	may cause ocular hypertension
atropine methonitrate		non-selective antagonism, blocks transmission in ganglia	antispasmodic in gastrointestinal hypermotility
trihexyphenidyl	Artane
tolterodine	Detrusitol
solifenacin	Vesicare
darifenacin	Enablex
benztropine	Cogentin

References

^ Rang, H. P. (2003). Pharmacology. Edinburgh: Churchill Livingstone. ISBN 0-443-07145-4. Page 147
^ ^a ^b ^c Unless else specified in table boxes, then ref is: Rang, H. P. (2003). Pharmacology. Edinburgh: Churchill Livingstone. ISBN 0-443-07145-4. Page 147

v • d • e

Drugs for functional gastrointestinal disorders (A03)

Drugs for functional bowel disorders

antimuscarinics: Mebeverine - Dicycloverine - Propantheline

papaverine and derivatives: Papaverine - Drotaverine - Moxaverine

acting on serotonin receptors: 5-HT₃ antagonists (Alosetron, Cilansetron) - 5HT₄ agonists (Mosapride, Tegaserod)

other: Diisopromine - Isometheptene - Phloroglucinol - Proglumide - Tridihexethyl

Belladonna and derivatives
(antimuscarinics)

Atropine - Hyoscyamine - Butylscopolamine - Methylscopolamine

Propulsives

primarily dopamine antagonists (Metoclopramide/Bromopride, Domperidone, Alizapride) - serotonin agonists (Cisapride) - Clebopride

v • d • e Urologicals (G04)
Acidifiers	Ammonium chloride, Calcium chloride
Urinary antispasmodics (primarily antimuscarinics)	Darifenacin, Emepronium, Flavoxate, Meladrazine, Oxybutynin, Propiverine, Solifenacin, Terodiline, Tolterodine, Trospium
For erectile dysfunction	Alprostadil, Apomorphine, Moxisylyte, Papaverine, Phentolamine, Yohimbine, PDE5 inhibitors (Avanafil, Sildenafil, Tadalafil, Udenafil, Vardenafil)
Other urologicals	Acetohydroxamic acid, Collagen, Dimethyl sulfoxide, Magnesium hydroxide, Pentosan polysulfate, Phenazopyridine, Phenyl salicylate, Succinimide
For benign prostatic hypertrophy	5α-reductase inhibitors: Dutasteride, Finasteride Alpha blockers: Alfuzosin, Doxazosin, Tamsulosin, Terazosin Herbals: Pygeum africanum, Serenoa repens

v • d • e Ophthalmologicals: mydriatics and cycloplegics (S01F)
Anticholinergics/antimuscarinics	Atropine - Scopolamine - Methylscopolamine - Cyclopentolate - Homatropine - Tropicamide
Sympathomimetics	Phenylephrine - Ephedrine - Ibopamine

v • d • e Receptor agonists and antagonists (and reuptake inhibitors)
Dopamine receptor	Dopamine agonist - Dopamine antagonist - Dopamine reuptake inhibitor
5-HT (serotonin) receptor	Serotonin receptor agonist - Serotonin antagonist (5-HT₃ antagonist) - Serotonin uptake inhibitor (SSRI)
Adrenergic receptor	adrenergic agonist (Adrenergic alpha-agonist, Beta2-adrenergic receptor agonist) - adrenergic antagonist (Alpha blocker, Beta blocker) - Adrenergic uptake inhibitor
Acetylcholine receptor	cholinergic (Muscarinic agonist, Nicotinic agonist) - anticholinergic (Muscarinic antagonist, Nicotinic antagonist) - Acetylcholinesterase inhibitor
Histamine receptor	Histamine agonist - Histamine antagonist (H₁, H₂)
GABA receptor	GABA agonist - GABA antagonist
NMDA receptor	NMDA antagonist