Cholinergic Agonists And Antagonists 2 Flashcards
Actuation of which receptor most likely evoke the greatest vasodilation by acting on receptors of the vascular smooth muscle?
β2
Activation of α1 receptors causes vasoconstriction
What the 3 different classes of cholinergic antagonists?
- muscarinic receptor antagonists
- nicotinic receptor antagonists: ganglion blockers and NMJ blockers
- drugs that act presynaptically
Atropine is a ________
Reversible competitive Muscarinic receptor antagonist and thus prevents acetylcholine from binding at that site
_______, ________,. And _______ drugs have significant anti muscarinic effects
Antihistaminic, antipsychotic, and antidepressant
Atropine is a ______ amine
Tertiary; CNS and peripheral muscarinic blocker
Effects of atropine on the eye, GI and urinary system
Eye: mydriasis (dilation), cyclopegia (relax of lens to see farther)
GI: ↓ gastric motility
Urinary system: ↓ hypermotility of urinary bladder
What is the effect of LOW dose atropine on the heart?
BRADYCARDIA due to: blockage of the presynaptic M2 receptors which normally inhibit acetyl choline release
What is the effect of moderate to high therapeutic doses of atropine on the heart?
TACHYCARDIA due to: blockade of the atrial M2 receptors which are post synaptic and causes opposite effects of muscarinic receptors
Atropine flushing is cutaneous vasodilation seen with ________
High doses of atropine
Effect of atropine on glands:
Salivary, sweat and lachrymal glands are BLOCKED
Blockage of sweat glands can cause high body temperature (fever)
Adverse effects of atropine
- dry mouth, blurred vision, sandy eyes, tachycardia, constipation, urinary retention
- effects on CNS: restlessness, confusion, hallucinations, delirium’s which can progress to depression, and collapse of circulatory and respiratory systems and death
What is the use of scopolamine?
Prevention of motion sickness
Sometimes used in anesthesia procedures because it blocks short term memory
What are the two classes of synthetic and semisynthetic drugs:
Quaternary ammonium muscarinic antagonists
Tertiary amine muscarinic antagonists
What are the two quarternary ammonium muscarinic antagonists and what is their main use
- ipratropium and tiotropium
- used as inhalation drugs in the treatment of COPD and sometimes asthma
They block M3 receptors → bronchodilation
_________ is used in inhalational drugs for treating COPD
Ipratropium or tiotropium
What are the tertiary amine muscarinic antagonists?
Homatropine and tropicamide
___________ is preferred over atropine for mydriasis for funcodscopy because it has a shorter duration fo action
Homatropine or Tropicamide
Which tertiary amine muscarinic antagonists are used to treat Parkinson’s and the extrapyramidal effects of antipsychotic drugs?
Benztropine and trihexyphenidyl
Uses of glycopyrrolate
- orally to inhibit GI motility
- paraenterally to prevent bradycardia during surgery
_________ is used for an overactive bladder
Tolterodine
Antimuscarinic agents are contraindicated in:
- patients with angle closure glaucoma
- careful with patients with prostatic hypertrophy
- elderly patients
What are the two mechanism of ganglion blocker drugs in the anti nicotinic agents
- prolonged depolarization: nicotine
- antagonism of nicotinic receptors: hexamethonium and mecamylamine
_________ and ________ are antinicotinic receptor drugs that cause ganglion blockade by directly antagonizing the nicotinic receptors
Hexamethonium and mecamylamine
The effect of ganglion blockers is to ____________
Remove dominant control of various organs
What are the two types of neuromuscular blockers?
- competitive antagonists (non depolarizing blockers): tubocurarine
- agonists (depolarizing blockers): succinylcholine
What are some adverse effects of depolarizing agents?
- malignant hyperthermia due to excessive release of calcium from SR
_____________ is given to treat the adverse effect of malignant hyperthermia seen when giving depolarizing agents
Dantrolene
Malignant hyperthermia is an adverse effect seen when giving ____________
Succinylcholine and halogenated anesthetic
What drug is an inhibitor of acetylcholine synthesis? What is is its mechanism of action?
Hemicholinium-3
Blocks choline transporter 1 aka CHT1 (symport with sodium) and prevents the uptake of choline required to synthesize acetylcholine
What is the mechanism of action of vesamicol?
It is a acetylcholine storage inhibitor
Blaise the Acetylcholine-H antiporter that is used to transport acetylcholine into vesicles
Mechanism of action of botulinum toxin
Inhibits acetylcholine release
An ophthalmologist gives a patient a drug to dilate her pupils. What kind of drug did she give the patient?
M3 antagonist
