Antimuscarinics Flashcards
Dicyclomine hydrochloride acts on
M3 receptors as an intestinal antispasmodic agent; spastic colon
Tropicamide produces
Short-acting mydriasis and cycloplegia
Used to treat overactive bladder
Oxybutinin chloride
Tolterodine
Darifenacin
Solifenacin
Benztropine and Biperiden
Centrally acting
Adjunct in the therapy of all forms of Parkinsism and control of EPS
Ipratropium and Tiotropium
Used exclusively for effect on respiratory tract; bronchodilator; COPD and bronchial asthma except in acute conditions
Glycopyrrolate is used for
reducing secretions in the mouth, throat, airway, and stomach before surgery
Propantheline bromide
used for hyperhidrosis
Quaternary amine derivatives of synthetic and semi-synthetic antimuscarinics
Ipratropoium
Tiotropium
Glycopyrrolate
Propantheline bromide
Tertiary amine derivatives of synthetic and semi-synthetic antimuscarinics
Dycyclomine Tropicamide Oxybutinin chloride Tolterodine Darifenacin Solifenacin Scopolamine
Tissues most sensitive to atropine
Salivary, bronchial, and sweat glands
Tissues least sensitive to atropine
Gastric parietal cells
Selectivity of atropine
Non-selective, does not distinguish among M1, M2, and M3
Selectivity of quaternary ammonium derivatives of atropine
Generally potent at muscarinic receptors and greater degree of nicotinic blockade
Hierarchy of relative senstivities to atropine in decreasing order
Salivary and sweat glands (xerostomia, anhydrosis, atropine fever)
Heart and eyes (tachycardia and blurred vision, mydriasis, cycloplegia, and reduced lacrimal secretion)
Smooth muscles (constipation, and urinary retention)
Gastric parietal glands (LAST)
CNS (TOXIC–> excitation)
Prominent difference in clinical manifestation between atropine and scopolamine
Scopolamine crosses BBB and may cause depression, drowsiness, amnesia, fatigue, dreamless sleep, reduced REM sleep, euphoria, and excitation
Antimuscarinic effect in the HEART
Modest tachycardia, blocks vagal effects on M2 receptors on SA node
At low doses, what is the effect of antimuscarinics on the heart
Bradycardia due to central effect via inhibition of the secretions of the medulla (decreased catecholamines)
At higher doses, murscarinic receptors are blocked, producing modest tachycardia
Antimuscarinic effect in the GIT
M3 block: Decrease tone and propulsive movements
Relaxed GIT walls
Prolonged gastric emptying time
M1 block: (by Pirenzepine and Telenzepine) inhibit gastric acid secretion
Pirenzepine and Telenzepine action
M1 blockade: inhibit gastric acid secretion at lower doses without affecting the gastric walls
Acid Peptic Disease
Dicyclomine is used in the GIT to
M3 block: reduce intestinal spasm
Antimuscarinic effect in the GUT
M3 block: smooth muscles of the bladder and ureters are relaxed, sphincters are contracted
Slows voiding
Treatment of urgency, frequency, and overactive bladder, urinary retention in BPH
Effective in overactive bladder and urinary incontinence
Selective M3 blockade:
Solifenacin
Darifenacin
Fesoteridine
Antimuscarinic effect in the ocular system
Unopposed sympathetic dilator activity in the pupillary constrictor muscle –> mydriasis
Weakened contraction of the ciliary muscle (cycloplegia)–> cannot accommodate
Reduced lacrimation or sandy eyes
Antimuscarinic effect on the respiratory tract
Bronchodilation
Reduced bronchial secretions
Decreased mucociliary clearance–> mucous plug
Dry mouth
