Cholinergic Antagonists Flashcards
Review: effect of cholinergic agonists - eye
- miosis
- accomodation
Review: effect of cholinergic agonists - lungs
- bronchiolar constriction
- increased secretion
Review: effect of cholinergic agonists - GI tract
- increased motility
- increased secretions
Review: effect of cholinergic agonists - GU tract
- bladder emptying
Review: effect of cholinergic agonists - CV system
- decreased vascular resistance
- bradycardia
Review: effect of cholinergic agonists - sweat glands
- diaphoresis (sweating)
Review: effect of cholinergic agonists - CNS
- stimulation
Review: effect of cholinergic agonists - NMJ
- muscle contrction
What is the response seen when a receptor binds an agonist?
- same as the endogenous compound for which the receptor was designated
What is the response seen when a receptor binds an antagonist?
- often the opposite as the agonist
What other names are muscarinic antagonists known as?
- parasympatholtyics
- antimuscarinic
What is the effect of a muscarinic antagonist?
- blocks effect of parasympathetic autonomic dischange
What are examples of muscarinic antagonists?
- atropine, scopolamine
What is the effect of nicotinic antagonists in the ANS and NMJ?
- ganglionic blockers (ANS)
- neuromuscular blockers (NMJ)
What is the effect of atropine on the eye?
- mydriasis (pupil dilation), opposite of miosis
What is the action of atropine?
- reversibly blocks muscarinic receptors
What is the mechanism of atropine’s action?
- prevents ACh from binding to muscarinic receptors
T/F: Atropine typically blocks actions of endogenous acetylcholine better than it blocks exogenously administered cholinergics.
False, exogenous > endogenous
What are the most sensitive areas to atropine?
- salivary
- bronchial
- sweat glands
What are the effects of anticholinergics on the CNS?
- atropine has minimal effect/use
- scopolamine can produce drowsiness and amnesia which is useful as an antiemetic
What can scopolamine toxicity in the CNS cause?
- CNS excitement
- agitation
- hallucinations
- coma
What are the clinical uses & drugs of anticholinergics on the CNS?
- adjuncts to treat Parkinson’s tremors (Benxtropine)
- prevention of motion sickness (scopolamine injx, oral, or patch)
What are the effects of anticholinergics on the eye?
- block cholinergic stimulation of pupillary constrictor muscles, result in unopposed sympathetic dilation (mydriasis)
- prevents contraction of ciliary muscle, results in loss of accommodation (cycloplegia)
- decreases lacrimal secretions (dry eyes)
What is a contraindication of anticholinergic use and why?
- glaucoma
- decreases outflow of aqueous humor
What clinical use do anticholinergics have?
- mydriasis and cycloplegia are useful to ophthos to view retina
What are the effects of low dose antimuscarinics on the CV system?
- blocks M1 receptors only: bradycardia
- because ACh still binds to M3 on sinus node that results in slowed HR
What are the effects of moderate to high doses of antimuscarinics on the CV system?
- blocks M1 & M2: tachycardia 2ndary to blockade of vagal slowing
- inhibiting the brakes on HR
What is a clinical use of moderate to high doses of antimuscarinics on the CV system?
- tx bradycardia in ACLS
- atropine
What are the effects of toxic doses of antimuscarinics on the CV system?
- intraventricular conduction block (cessation of HR)
- little effect on BP
What are the effects of anticholinergics on the respiratory system?
- bronchodilation
- reduce/dry up secretions
What are the therapeutic uses and drugs of anticholinergics on the respiratory system?
- asthma/COPD (ipatropium, titropium)
- prior to surgery or in vented patients (atropine, scopolamine)
What are the effects of antimuscarinics on the GI tract?
- decrease motility via decrease GI smooth M. contraction
- decrease salivary and GI secretions (xerostomia)
What are the therapeutic uses of antimuscarinics on the GI tract?
- tx: diarrhea (atropine, inotecan) via decrease GI secretions
T/F: Antimuscarinics do not affect acid secretions in the stomach.
- True
T/F: Anticolinergic agents cannot cause significant constipation.
- False
What is the effect of antimuscarinics on the GU tract?
- relaxation of bladder smooth muscle, leads to reduced voiding
What group of patients can atnimuscarinics worsen urinary retention in?
- men with BPH (benign prostatic hyperplasia)
What are the clinical indications of antimuscarinics in treating urinary disorders?
- tx: urinary spasms (oxybutinin, a selective M3 antagonist)
What is an effective treatment for muscarinic toxicity?
- atropine
What is the treatment for rapid onset mushroom poisoning?
- atropine
What is the treatment for delayed onset mushroom poisoning?
- supportive care
- atropine ineffective
What is a treatment for hyperhidrosis?
- anticholinergics
T/F: anticholinergics are always effective on sweat glands.
- False, different types of sweat glands
- eccrine > apocrine
What are the adverse effects of anticholinergics?
- dry mouth (dry as a bone)
- mydriasis (blind as a bat)
- tachycardia
- hot, flushed skin (red as a beet)
- agitation (mad as a hatter)
- urinary retention (can’t pee)
- visual changes (can’t see)
- dry mouth (can’t spit)
- constipation (can’t shit)
What are the contraindications of anticholinergic use?
- glaucoma
- BPH
- gastric ulcers (due to slowed gastric emptying)
What happens during presynaptic inhibition of cholinergic actions?
- presynaptic proteins block the release of ACh
What is the result of presynaptic inhibition of cholinergic actions?
- paralysis of skeletal m.
- decreased activity at parasympathetic and sympathetic synapses
- inhibition lasts weeks to months
What are the drugs used for presynaptic inhibition of cholinergic actions?
- Clostridum botulinum: onabotulinum, abobotulinum, rimabotulinum
What is the MOA of ganglionic blocking agents?
- block ACh and its agonists at nicotinic receptors of para and sympathetic ganglia
What are ganglionic blocking agents also known as?
- nondepolarizing competitive antagonists
What is the overall result of ganglionic blocking agents?
- blocking all autonomic outflow
- mixed sympathetic and para effects
What are the effects of ganglionic blockers at the CNS?
- sedation
- tremor
- choreiform (abnormal) movements
- mental aberrations
What are the effects of ganglionic blockers at the eye?
- cycloplegia
- loss of accommodation
- moderate dilation of pupil
What are the effects of ganglionic blockers at the CV system?
- tachycardia
What are the effects of ganglionic blockers at the GI tract?
- decreased secretions
- decreased motility
What is the major use of therapeutic ganglionic blockers?
- pharmacological research
What is the action of neuromuscular blockers?
- block transmission b/t neuron and nicotinic receptor on skeletal m.
What are the two groups of neuromuscular blockers?
- nondepolarizing (antagonists)
- depolarizing (agonists)
Describe the action of nondepolarizing neuromuscular blockers
- block ACh from binding nicotinic receptors
- competitive binding
- prevents depolarization of muscle fibers and inhibits contraction
What is the result of a nondepolarizing neuromuscular blockers?
- very relaxed/paralyzed muscle
What can terminate the action of nondepolarizing neuromuscular blockers?
- AChE inhibitors (neostigmine)
What is the clinical use of nondepolarizing neuromuscular blockers?
- adjuncts to anesthesia to produce muscle paralysis/relaxation
What are the groups of nondepolarizing neuromuscular blockers drugs?
suffixes:
- curarine
- curium
- curonium
How do the different nondepolarizing neuromuscular blockers drugs differ?
- onset of action
- 1/2 life
- means of elimination
Describe the action of depolarizing neuromuscular blockers
- binds to nicotinic receptors on skeletal m. and acts like ACh
What is the initial effect of depolarizing neuromuscular blockers?
- facilitates muscle contraction
What is the effect of prolonged depolarizing neuromuscular blockers?
- muscle paralysis
What is a drug used as a depolarizing neuromuscular blockers?
- succinylcholine
What are the clinical uses of depolarizing neuromuscular blockers?
- facilitate intubation
- during electroconvulsive shock therapty
Give some therapeutic uses of anticholinergics
- diarrhea
- bradycardia
- asthma/COPD
depolarizing or nondepolarizing neuromuscular blocker: tubocurarine
- non
depolarizing or nondepolarizing neuromuscular blocker: atracurium
- non
depolarizing or nondepolarizing neuromuscular blocker: succinylcholine
- depolarizing
depolarizing or nondepolarizing neuromuscular blocker: rocuronium
- non
depolarizing or nondepolarizing neuromuscular blocker: doxacurium
- non
depolarizing or nondepolarizing neuromuscular blocker: vecuronium
- non
