Cholinergic Agonists Flashcards
Choline esters - name 3.
Methancol
Carbachol
Bethanecol
Bethanechol - what is the action?
“Beth - call me to activate your BOWEL and BLADDER”
activates bowel and bladder via Muscarinic receptors
resistant to AChE
Carbachol
“A carbon copy of ACh”
stimulates nicotinic and muscarinic
pupillary constriction, relieves intraoccular pressure
Methacholine
Stimulates muscarinic receptors in airway when inhaled
Use as challenge test for asthma ddx.
Alkaloids - give several examples
Muscarine
Pilocarpine
Oxotremorine
Nicotine
What occurs with muscarinic stimulation of the eye?
Constricts pupil
Facilitates NEAR vision
decreases intra ocular pressure
Think: GLAUCOMA - pilocarpine given
What occurs with muscarinic stimulation of the heart?
Muscarinic stim –> vagal stimulation = BRADYCARDIA!
Atrial and SA nodes effected
AV NODE IS SLOWED
Blood vessels have what type of receptors?
M3
Stimulation of M3 receptors on BV leads to what?
Dilation of vessels via NO release.
Muscarinic agonists do what to the lungs?
Bronchoconstrict
Increase bronchiole secretions
This is why we give methacholine to challenge asthma ddx.
Name a muscarinic agonist that increases cholingergic effect and has a STRANGE side effect.
Arecoline –> causes red saliva
When treating glaucoma, what do we use?
Drops into eye to open angle.
Use with atropine to break adhesions between iris and lens.
What is a side effect of treating with pilocarpine?
Salivation, sweating.
2-3L sometimes.
What is cevimeline?
A selective M3 agonist.
Less side effects, longer action.
Less sweater.
Side effects from muscarinic side effects?
Sweat increased gut activity drooling bronchospasm tears
Why is poisoning with mushrooms a concern? What do we treat with?
Mushrooms are muscarine agonists.
Treat with atropine (ANTAGONIST) and Epi.
Which receptors sensitize rapidly?
Nicotinic
Compare low dose nicotinic stimulation in brain to high dose stimulation?
Low dose:
increased alertness and attention
High Dose
tremor, emesis, increased RR
Toxicity:
convulsions
Does Nicotine activate PSNS or SNS?
Both!
What are some effects of Nicotine toxicity?
vomiting
CNS overstim (convulsions, coma, respiratory arrest)
Skeletal mm depol (blocks NMJ and get paralysis)
Cardio: HTN and arrhythmia
How to treat nicotine poisoning?
Atropine blocks M receptors
Anticonvulsant
Assist Respiration
What does Chantix do?
partial agonist on nicotine receptor in brain
prevents cravings
blocks effect of nicotine if smoke
Name some cholinesterase inhibitors?
“-stigmines” and “-phoniums”
Neostigmine (myasthenia gravis)
Physostigmine
Donezipil
Edrophonium (myasthenia gravis)
What is one toxic substance that works as a cholinesterase inhibitor?
Organophosphates
What’s are some concerns with Neostigmine?
Use post op to remove neuromuscular blockade (NMB), but has poor oral absorption and doesn’t enter CNS.
Use to increase bladder motility, treat MG, and reverse NMB
What cholinesterase inhibitors enter the CNS?
Physostigmine
Think it “phyxs” an atropine overdose
Give in the eye
Endrophonium - what is it good for?
Cholinesterase inhibitor
reversible, short acting
What can we use against organophosphate poisoning?
2PAM - but not for carbamates!
What is 2PAM?
binds and inhibits AChE
most effective at NMJ
does not enter CNS
Some effects of AChE inhibitors?
CNS - improved alertness and memory
Eye - meiosis
GI, Bladder stim
Respiratory- salivation, secretion, bronchoconstric
Cardio effects of AChE inhibitors?
Sympathetics dominated by Nicotine
So - see heart with bradycardia, decreased force
BP has little effect - no cholinergic innervation
What is Donezipil often used for?
Donezipil = aricept
AChE inhibitor that penetrates CNS
Also could be
Aricept, Exelon, Reminyl, Cognex
How does Echothiophate work? What do we use it for?
Organophosphate AChE inhibitor
IRREVERSIBLE inhibition of AChE
use topically to produce long lasting decrease in Pressure
What is DFP? Why is it dangerous?
organophosphate
irreversibly binds AChE
lipid soluble, penetrates CNS
How do soman, sarin, and tabun work?
neve gases
organophosphates
How should we treat glaucoma?
Direct agonist:
pilocarpine or carbachol (lowers P)
Cholinesterase Inhib
also could be used
Two possible drugs for GI/Urinary?
Bethanechol more common
Used to also be neostigmine
Name the TOXICITIES For AChE
SLUDGE
salivation
lacrimation
urination
defecation
gastric distress
emesisWhat do we give for organophosphate AChE inhibitor poisoning?
atropine
2-Pam if w/in 3-4hrs of exposure
Diazepam for seizures
What can cause carbamate AChE poisoning?
Sevin
Baygon
Temik
