Cholinergics:Muscarinic Receptor Antagonist Flashcards
competitively block muscarinic receptors (parasympatholytics, antimuscarinics)
Muscarinic receptor antagonist
Are muscarinic receptor antagonists selective for receptor subtypes?
no
Effect of muscarinic receptor antagonist:
_____ iris sphincter and ciliary muscles – mydriasis and paralysis of accommodation (cycloplegia)
relax
Effect of muscarinic receptor antagonist:
_______ non-vascular smooth muscle (airways, GI tract, urinary bladder)
relax
Effect of muscarinic receptor antagonist:
_______ heart rate
increase
Effect of muscarinic receptor antagonist:
______ exocrine gland secretion (sweat, salivary, lacrimal, intestinal, mucosal glands)
inhibit
Effect of muscarinic receptor antagonist:
CNS effects
- low (therapeutic) doses produce _______
- higher, toxic doses produce _________
sedation
excitement, delirium, agitation, toxic psychosis
muscarinic receptor antagonist:
effectively treat bradyarrhythmias due to high vagal tone~~~ specifically MI or hyperactive carotid reflex
Atropine
muscarinic receptor antagonist:
to produce mydriasis (dilation) and cylcoplegia (paralysis of accommodation)
Atropine
Duration of action of Atropine
- long duration of action (7-10 days) -
What drug would I use to allow for thorough examination of the retina and optic disc
and to allow certain surgical procedures - treat acute iritis or choroiditis
Atropine
muscarinic receptor antagonist:
uses in anesthesia: - commonly given to block responses to vagal reflexes induced by
surgical manipulation of visceral organs
Atropine
- use to treat anticholinesterase or muscarinic toxicity
Atropine
tx motion sickness
Scopolamine
Which penetrates CNS better: scopolamine or atropine
scopolamine
which alkaloid muscarinic receptor antagonist works through CNS?
scopolamine
Use to tx vestibular disease
scopolamine
Used to tx crhonic obstructive pulmonary disease
Ipratropium
Good for COPD but less so for asthma
Ipratropium
Drug that reduces secreations and reduces bronchoconstriction
Ipratropium
Adminstration of Ipratropium
inhialer
Does Ipratropium penetrate CNS?
No
How does Ipratropium tx COPD
reduces bronchoconstriction and reduced secreations
Good for fast eye dialation
Tropicamide
Tropicamide effects
dialation and paralysis of ciliary muscle so loss of accomidation
Tropicamide is what type of drug
Muscarinic receptor antagonist
Tropicamide has fast/slow onset and long or short duration
fast onset and short duration
- used to treat overactive bladder and incontinence
bad choice
Oxybutynin
Whats the downside of using oxybutynin?
- high incidence of anti-muscarinic side effects
- xerostomia mainly, but also blurred vision, GI (constipation) & CNS (drowsiness, confusion) antimuscarinic effects
- used to treat overactive bladder and incontinence (good choice)
Darifenacin
Why is darifenacin a better choice then oxybutynin for overactive bladder?
selective M3 blocker so less CNS side effects
used to block parasympathomimetic effects during reversal of neuromuscular blockade with anticholinesterase agents
Glycopyrrolate
Glycopyrrolate penetrate CNS?
quaternary amine so no CNS penetration
If you use neostigmine to reverse skeletal muscle paralysis, you get parasympathomimetic effect… you can use _______ so we don’t overdo it with the neostigmine
Glycopyrrolate
Glycopyrrolate stops what type of symptoms from neostigmine
SLUDGE
Side effects of muscarinic receptor agonists
- Hot as a hare (no sweating)
- Dry as a bone (dry mouth, dry hot skin, no sweating)
- Red as a beet (due to excessive heat and no sweating)
- Blind as a bat (mydriasis, cycloplegia, blurred vision)
- Drowsiness (CNS action)
Three pt profiles to be careful when using muscarinic receptor antagonists
Glaucoma (d/t eye issues)
Benign Prosthetic hyperplasia (already have issues urinating)
Any pt with tachycardia
What drug do we use to tx poisoning of muscarinic receptor agonists?
physostigmine if severe bc it’s an AchE inhibitor that will penetrate CNS
