Lecture 3 Flashcards
prototype drug for antimuscarinic agents
Atropine
Competitive antagonist mechanism
Anticholinergics that bind to the receptor and disrupts ACh binding.
Atropine effect on muscarinic receptors
They block them by being competitive antagonists at M1,2 and 3 at postganglionic
Atropine also has action on_____
Smooth muscle that lack innervation
Atropine effect on nicotinic receptor
Little effect on actions of ACh at nicotinic receptors
Atropine effect on CNS
Can produce partial block on M1 at high doses
Does acetylcholine bind pre or post synaptically
Post
effect of atropine on exocrine glands, what receptor does it act on?
decreased secretions
decreased sweating
M3 receptor
Therapeutic use of atropine on exocrine glands
Preanesthetic, peptic ulcers, OTC and cold remedies
Adverse effects of atropine on exocrine glands
Dry mouth
hyperthermia in children
effect of atropine on eye, what receptor does it block
Blocks M3 receptor.
Causes mydriasis
therapeutic use of atropine in eye
opthalmic examination or procedure
adverse effects of atropine on eye
exacerbation of glaucoma
effect of atropine on CVS, what receptor does it act on
Increase heart rate, M2 receptor
Therapeutic use of atropine in cardiovascular system
bradyarrythmia, heartblock
adverse/toxic effects of atropine on CVS
Tachycardia, increased risk of VF in acute MI
effect of atropine on respiratory tract, what receptors does it act on?
Block of vagal bronchoconstriction
M2 and M3
use of atropine therapeutically in respiratory tract
Treatment of COPD and asthma
effects of atropine on urinary bladder
decreased urinary frequency
toxic effects of atropine in urinary system
urine retention
effects of atropine in GI smooth muscle
decreased motility (might lead to constipation)
effects of atropine on GI smooth muscle
Constipation
effects of atropine on CNS
Blocks all muscarinic receptors
Therapeutic use of atropine on CNS
Anti motion sickness, anti parkinsosn
toxic effects of atropine on CNS
Coma, confusion, depression
Difference between tertiary amines like atropine and quaternary amines
Tertiary amines can be used in ocular and CNS application. Quaternary amines are mainly used in GI tractand peripheral applications
Antagonist vs agonist size difference
Antagonist is much bigger
Why do tertiary amines have CNS access
Nitrogen is not charged
Structural difference between atropine and scopolamine? How does this change the effects?
Scopolamine has an extra oxygen. This makes it more lipophilic. Making it have better CNS access.
How does clinical use in anti muscarinic drugs depend on drug duration
Less duration= less side effects
Scopolamine use
Motion sickness treatment
homatropine and tropicamide clinical uses
optical application
benztropine clinical use
Parkinsons disease
What two drugs are used in conjunction to treat parkinsons
Benztropine, L-Dopa
Ipratropium clinical use
Same as atropine, but is charged. COPD
How does ipratropium treat COPD
M3 Antagonist, dilates bronchi.
What two drugs are used in conjunction to treat COPD
Albuterol and Ipratropium
Longer acting analog of ipratropium
Tiotropium
Glycopyrrolate used for
GI spasms and peptic ulcers
Tolteridon clinical use
Acts selectively on M3 and used for Overactive bladder
How do we treat antimuscarinic effects
Physostigmines
How do physostigimines treat antimuscarinic effects
ACHe inhibitor
Nm on which tissue? Nn on which tissue?
Skeletal muscle
post ganglionic
what is a common feature between muscarinic and nicotinic receptors
ACHe
Features of neuromuscular blocking agents
They look like ACh
Succinylcholine (SUX) structure
ACh dimer
2 main nicotinic blockers
Tubocurarine
SUX
tubocurarine blocking mechanism
non-depolarizing nicotinic blockade
SUX mechanism of blockade
Depolarizing blockade
Mechanism of nicotinic receptros
ACh binds postsynaptically to nicotine and becomes inactive
Depolarizes membrane
sodium comes in
ACHe binds ACh and breaks it down
Goes back to active state
Difference between tubocurarine and succinylcholine
Succinylchoine has permanent depolarization because ACh remains bound to receptor, Tubocurarine has non-depolarizing nicotinic blockade.
Persistent depolarization definition
AChE does not break down ACh down and remains bound. Na+ channels stay in an inactive state and cannot reset to active state
What is Succinylcholine (SUX) metabolized by? Rate of degradation compared to ACh and ACHe
Butyrylcholinesterase. Much slower than AChE.
Butyrylcholinesterase breaks ACh down into
Choline. Increases BP
Clinical use of Succinylcholine (SUX)
Skeletal muscle relaxation during anesthesia and electroconvulsant therapy.
Indirect inhibitor of ACh RELEASE
Botulinum toxin
Clinical use of botulinum toxin
Cerebral palsy, uncontrolled muscle spasms
Hexamethonium action
blocks ALL of the sympathetic and Parasympathetic activity to treat HTN. Discontinued.
effect of hexamethonium on blood vessel
Hypotension
effects of hexamethonium on sweat glands
decrease sweat excretion
effects of hexamethonium on Heart rate
increases HR
effects of hexamethonium on eye
Pupillary dilation and blurred vision
Effect of hexamethonium on gut
Deccreases gut motility
effect of hexamethonium on bladder
Urinary retention