Cholinergic Agonists and Antagonists Flashcards
What are the functions of the M1 muscarinic receptor?
Activates myenteric plexus
What are the functions of the M2 muscarinic receptor?
Decreases HR and contraction via opening of the K channels
What are the functions of the M3 muscarinic receptor?
Pupillary constriction Bronchoconstriction Increase GI motility Contract bladder detrusor Stimulate salivary secretion
What are the muscarinic receptors?
M1
M2
M3
What are the nicotinic receptors?
Nn
Nm
What is the Nn receptor?
Neuronal nicotinic receptor
What is the Nm receptor?
Muscle cell nicotinic receptor
What receptor does nicotine bind?
Nn
What is the effect of nicotine?
Diffuse activation of central and peripheral nicotinic receptors
Nicotine indication
Limited to preparations for smoking cessation often in a transdermal patch
Nicotine Toxicity
Effects include irritation at site of administration and dyspepsia
What does succinylcholine stimulate?
Succinylcholine sticks on the Nm receptor for a
long period of time and that leads to prevention
of action potential conduction by blocking the Nm receptor
Succinylcholine indication
Used clinically as a muscle relaxant during intubation or electro convulsive shock therapy
Succinylcholine Contraindications
Familial hyperthermia
Skeletal muscle myopathies
What are the types of muscarinic agonists?
Quaternary nitrogen analogs
Tertiary amine alkaloids
Synthetic analogs
What does ACh stimulate?
Binds to both nicotinic and muscarinic receptors of the autonomic nervous system, the CNS and the neuromuscular junction.
ACh indication
It is rapidly hydrolyzed by acetyl- and plasma cholinesterases. Therefore, it has no therapeutic use.
What does methacholine stimulate?
Primarily muscarinic effects on smooth muscle, glands and heart
Methacholine indication
Used to diagnose bronchial hyperactivity in patients suspected of having asthma
Methacholine Toxicity
Bronchiolar constriction
Methacholine Contraindications
Contraindicated in pts given β-blockers since antidote to overdose is β-agonist.
What does carbachol stimulate?
Muscarinic and nicotinic activity
Is carbochol easily hydrolyzed by AChE?
Resistant to hydrolysis by AchE
Carbachol indication
Miotic agent for ocular surgery and glaucoma
Used as an intraocular injection to reduce pressure after cataract surgery
Carbachol Toxicity
Side effects are related to excessive muscarinic and nicotinic receptor activation i.e., bronchoconstriction, reduced cardiac conduction
Bethanechol targets
Muscarinic selectivity
Bethanechol hydrolysis
It is resistant to hydrolysis by cholinesterases
What is the effect of bethanechol?
It has selective action on muscarinic receptors of GI tract and urinary bladder and minimizes the cardiac effects.
Bethanechol indication
Post-op urinary retention
Neurogenic bladder atony
Bethanechol Toxicity
Bradycardia
Bronchoconstriction
Bethanechol Contraindications
Asthma
Peptic ulcer
Bradycardia
What are the quaternary nitrogen analogs?
Methacholine
Carbachol
Bethanechol