Anticholinergics: Antimuscarinics Flashcards
Anticcholinergics
-bind to receptor and disrupt acetylcholine binding
-competitive ANTAgonists
-reversible
Effects of antimuscarinic agents
-block muscarinic receptor
-ganglia: little effect on actions of ACh at the NICOTINIC receptor
-CNS: widespread distribution of muscarinic receptors throughout brain
Atropine
-oldest antimuscarinic agent
-antagonist at M1, M2, M3
-can produce partial block (M1) only at relatively high doses
Antimuscarinics
-muscarinic receptor ANTAgonists
-competitive and reversible
-block ACh from binding
Atropine effect on exocrine glands
-decreased sweating and secretions
-preanesthetic
Atropine effect on eye
-mydriasis
-dilation
Atropine effect on cardiovasc
-increase heart rate
-no effect on BP
-treat arrhythmia
atropine effect on respiratory tract
-block of vagal bronchoconstriction
Atropine effect on bladder
-decrease tone
-constricted sphincter
-reduce frequency
Atropine effect on GI smooth muscle
-decrease motility and tone
-treat hypermobility
Atropine effect on CNS
-block all muscarinic receptors
-anti-motion sickness
-anti-parkinsons
Antimuscarinic classes
-tertiary amines
-quarternary amines
tertiary amine antimuscarinics
-atropine
-mainly used in ocular and CNS applications
Quarternary amine antimuscarinics
-anisotropine
-mainly used in GI tract and PERIPHERAL applications
Tertiary amine antimuscarinic classes
-belladonna alkaloids (long last)
-tertiary amine derivatives (short acting)
-tertiary amine derivatives (antiparkinson)
belladonna alkaloid drugs
-long lasting
-atropine
-scopolamine
tertiary amine derivative drugs (short acting)
-homatropine
-tropicamide
tertiary amine derivative drugs (antiparkinson)
-benztropine (cogentin)
-trihexyphenidyl (artane)
Quarternary derivatives of belladonna alkaloids drugs
-Ipratropium (atrovent)
-tiotropium (spiriva)
belladonna alkaloids
-long lasting tertiary amines
-M1/M2/M3 non-selective
-treat GI and motion sick
-can affect CNS
-naturally occuring
-little bit of hallucinations
need to know
acetylcholine structure
Scopolamine
-3’ belladonna alkaloid
-higher CNS penetration than atropine= more drowsy and hallucinations
-highly lipophillic
Scopolamine clinical use
-motion sickness
-oral or transdermal
-dry mouth, blurred vision, sedation side effects
-confusion and psychosis at high doses
Short acting tertiary amines
-homatropine and tropicamide
-optical applications
-cycloplegia and mydriasis
Homatropine
-short acting 3’ amine
-less toxic than tropicamide
tropicamide
-short acting 3’ amine
-shorter duration than homatropine
Benztropine (congentin)
-treat parkinson
-sedative activity
-combo therapy with L-DOPA in patients
-similar potency to atropine
Ipratropium
-4’ amine
-M3 ANTAgonist
-block ACh-mediated constriction = open airways
Ipratropium clinical use
-treat COPD sometimes asthma
-enhances therapeutic effect of B-adrenergic AGonists in COPD
Combivent or Duoneb
-brand name for Ipratropium
-treat COPD
Ipratropium problems
-few bc poor absorption
-toxic doses may cause hypotension (ganglionic block) or muscle weakness (neuromuscular block)
tiotropium
-longer acting analog of Ipratropium
antimuscarinic 4’ Amines for GI disorders
-glycopyrrolate
-propantheline bromide
-treat spasms and ulcers
glycopyrrolate
-4’ amine
-pre-op to reduce secretions
-charged N makes crossing gut difficult
Antimuscarinics for overactive bladder
-tolterodine
-“fenacin” (M3 selective)
Tolterodine
-non-selective but favors M3 receptor
-treat overactive bladder
“fenacin”
-newer M3 selective antagonists
-treat overactive bladder
-lower constipation and confusion
Mirabegron
also a B3 agonist ?
Antimuscarinic poisoning
-over 600 meds with antimuscarinic effects
-diphenhydramine, chlorprozamine, amitriptyline
-dry mouth
Antimuscarinic poisoning treatment
-change meds/decrease dose
-sodium bicarb for QRS
-Benzos for delirium
-physostigmine (AChase inhibitor)
physostigmine
-AChASE inhibitor
-treat antimuscarinic poisoning
