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Neuro > Autonomic Drugs: Acetylcholine B&B > Flashcards

Autonomic Drugs: Acetylcholine B&B Flashcards

1
Q

name 5 places where acetylcholine receptors are found in the body

A
  1. muscarinic parasympathetic receptors in cardiac and smooth muscle, glands
  2. muscarinic sympathetic receptors in sweat glands
  3. nicotinic somatic receptors in skeletal muscle
  4. nicotinic receptors in 1st synapse of SNS and PNS
  5. nicotinic receptors at adrenal medulla
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2
Q

explain why flushing occurs with muscarinic antagonists

A

muscarinic receptors are found in parasympathetic system + SWEAT GLANDS of SNS

block muscarinic receptors —> no sweat —> increased body temp —> skin flushing

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3
Q

how do muscarinic agonists affect endothelial cells?

A

no direct effect on vascular smooth muscle

indirectly stimulate NO release —> activates guanylate cyclase —> less intracellular calcium —> vasodilation and lowered BP

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4
Q

what is the clinical use of the following acetylcholine agonists?
a. bethanechol
b. carbachol
c. pilocarpine
d. methacholine

A

a. Bethanechol: activates Bowel and Bladder to treat urinary retention

b. carbachol: lowers intraocular pressure to treat glaucoma or pupillary constriction
c. pilocarpine: lowers intraocular pressure to treat glaucoma

d. methacholine: bronchoconstrictor used to diagnosis asthma

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5
Q

name 2 acetylcholine agonists which lower intraocular pressure to treat glaucoma

A
  1. carbachol
  2. pilocarpine
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6
Q

what kind of drug is bethanechol?

A

Bethanechol: acetylcholine agonist, activates Bowel and Bladder to treat urinary retention (ex, after surgery)

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7
Q

what kind of drug are carbachol and pilocarpine?

A

acetylcholine agonists

carbachol: lowers intraocular pressure to treat glaucoma or pupillary constriction

pilocarpine: lowers intraocular pressure to treat glaucoma + treats Sjögren’s syndrome (increases salivation)

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8
Q

what kind of drug is neostigmine, and for what is it used?

A

acetylcholine esterase inhibitor (non-competitive, covalent but reversible) —> increases activity of ACh

used to treat urinary retention and myasthenia gravis

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9
Q

what kind of drugs are pyridostigmine and edrophonium, and what do they treat?

A

acetylcholine esterase inhibitor —> increases activity of ACh

edrophonium (competitive, reversible) - used for diagnosis of myasthenia gravis
pyridostigmine (non-competitive, covalent but reversible) - used to treat myasthenia gravis

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10
Q

what is physostigmine used for?

A

acetylcholine esterase inhibitor (non-competitive, covalent but reversible) —> increases activity of ACh

used to treat anti-cholinergic toxicity (such as by atropine) and glaucoma

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11
Q

a pt in the ED is accidentally given an overdose of atropine - what should you prescribe to reverse the effects?

A

atropine = anti-cholinergic drug

give physostigmine (ACh esterase inhibitor) to reverse the toxicity

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12
Q

what kind of drug is donepezil, and what does it treat?

A

acetylcholine esterase inhibitor —> increases activity of ACh

used to treat Alzheimer’s (in which there is decreased ACh activity)

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13
Q

what is the clinical use of the following acetylcholine esterase inhibitors?
a. neostigmine
b. pyridostigmine
c. edrophonium
d. physostigmine
e. donepezil

A

a. neostigmine - urinary retention, myasthenia gravis
b. pyridostigmine - myasthenia gravis (tx)
c. edrophonium - myasthenia gravis (dx)

d. physostigmine - anti-cholinergic toxicity (ex, atropine), glaucoma

e. donepezil - Alzheimer’s

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14
Q

which receptors are affected by myasthenia gravis? how does it present?

A

autoantibodies against ACh receptors, primarily nicotinic receptors in skeletal muscle

—> presents with problems of eye/chewing/talking/swallowing
—> classic finding is fatiguability due to decreasing ACh levels with more movement

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15
Q

COPD and peptic ulcers are similar in that they can both be worsened by what type of medication? explain

A

cholinergic (ACh agonist or ACh-esterase inhibitor) medication

bronchoconstriction —> COPD flare
increased gastric acid —> ulcers

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16
Q

Who is at risk for organophosphate poisoning and how does it present?

A

Exposure to insecticides often through skin (farmers) —> irreversible (covalent) blocker of acetylcholine esterase —> all ACh synapses in overdrive

  1. increased muscarinic activity —> diarrhea, urination, bronchospasm, bradycardia, salivation, lacrimation
  2. increased nicotinic activity —> muscle fasciculations
  3. increased CNS activity —> confusion, lethargy, seizures
17
Q

Pt is 44yo farmer presenting to the ER with difficulty breathing. There is audible wheezing. Pt reports diarrhea, and unintentional loss of urine. Pt appears agitated. PE reveals pinpoint pupils. Pt is sweaty, drooling, and eyes are watery. Pulse is 30.
What is likely going on?

A

organophosphate poisoning: exposure to insecticides often through skin (farmers) —> irreversible blocker of acetylcholine esterase —> all ACh synapses in overdrive

  1. increased muscarinic activity —> diarrhea, urination, bronchospasm, bradycardia, salivation, lacrimation
  2. increased nicotinic activity —> muscle fasciculations
  3. increased CNS activity —> confusion, lethargy, seizures
18
Q

How is organophosphate poisoning treated? Name 2 drugs used to treat.

A

exposure to insecticides often through skin (farmers) —> irreversible blocker of acetylcholine esterase —> all ACh synapses in overdrive

treat with:
1. atropine: muscarinic antagonist
2. pralidoxine: regenerates AChE (oxime group has high affinity for phosphate group in organophosphates, breaks interaction with cholinesterase)

19
Q

what kind of drugs are homatropine and tropicamide, and what are they used to treat?

A

acetylcholine antagonists - muscarinic blockers

used to dilate eyes (mydriasis), applied topically

20
Q

name 2 muscarinic blockers used to dilate eyes (mydriasis)

A
  1. homatropine
  2. tropicamide
21
Q

what kind of drugs are benztropine and trihexyphenidyl, and what are they used to treat?

A

acetylcholine antagonists - muscarinic blockers

used to treat Parkinson’s

22
Q

what kind of drugs are ipratropium and triotropium, and what are they used to treat?

A

acetylcholine antagonists - muscarinic blockers

used in inhalers to treat COPD

23
Q

name 2 muscarinic blockers used in inhalers to treat COPD

A
  1. ipratropium
  2. tiotropium
24
Q

what kind of drug is oxybutynin, and what is it used to treat?

A

acetylcholine antagonist - muscarinic blocker

used to treat urinary incontinence by reducing bladder spasms

25
Q

what kind of drug is glycopyrrolate, and when is it used?

A

acetylcholine antagonist - muscarinic blocker

used pre-operatively to reduce airway secretions

26
Q

what kind of drug is scopolamine, and what is it used to treat?

A

acetylcholine antagonist - muscarinic blocker

used to treat motion sickness (via patch)

27
Q

what occurs in motion sickness, and considering this, how can it be treated? name 2 specific drugs from 2 different drug classes

A

motion sickness = overstimulation of M1 and H1 receptors

  1. scopolamine patch: muscarinic blocker (M1)
  2. meclizine or dimenhydrinate (Dramamine): antihistamines (H1)
28
Q

what would be the side effects of a scopolamine patch for motion sickness? why does this make sense?

A

motion sickness = overstimulation of M1 and H1 receptors

scopolamine patch: muscarinic blocker (M1)

blocking acetylcholine at M1 receptors would also cause other symptoms related to parasympathetic nervous system such as: dry mouth, urinary retention, constipation

29
Q

What kind of drug is atropine? And when is it used? What are the potential side effects?

A

atropine = muscarinic antagonist used to treat bradycardia and to cause pupil dilation, also sometimes used in cardiac arrest to speed the heart up

toxicity would cause dampening of the parasympathetic system + loss of sweating (M1 used in sympathetic system for sweating)

30
Q

for what condition is atropine contraindicated and why?

A

atropine = muscarinic antagonist used to treat bradycardia and to cause pupil dilation, also sometimes used in cardiac arrest to speed the heart up

contraindicated in glaucoma!! decreases outflow of fluid and can cause sudden eye pain + halos

31
Q

what occurs in Gardner’s Mydriasis?

A

due to Jimson weed toxin, which acts similarly to atropine (muscarinic blocker)

—> dilated pupils, tachycardia, HTN, dry mouth

tx: physostigmine (AChE inhibitor)

32
Q

mechanism of botulism vs atropine overdose vs organophosphate poisoning

A

botulism = nicotinic + muscarinic blockage —> descending paralysis + GI symptoms

atropine overdose = muscarinic blockage —> lack of sweating + parasympathetic activity, no muscle effects

organophosphate poisoning = nicotinic + muscarinic activation —> fasciculations, miosis, bradycardia, tears, sweat

33
Q

what is the shared mechanism of bethanechol, pilocarpine, and muscarine?

A

direct acting muscarinic agonists: activates muscarinic (M) acetylcholine receptors leading to increased production of IP3 and diacylglycerol, or inhibition of adenylyl cyclase (depending on receptor subtype coupling)

34
Q

what would be the expected adverse effects of bethanechol, pilocarpine, and muscarine, and why does this make sense?

A

all direct-acting muscarinic agonists

side effects include parasympathomimetic effects: (cyclospasm, diarrhea, urinary urgency); vasodilation, reflex tachycardia, sweating

bethanechol - treats bladder/bowel retention
pilocarpine - treats Sjögren’s syndrome (to increase salivation)
muscarine - no clinical use, alkaloid found in mushrooms

35
Q

what is the mechanism of nicotine acting on nicotinic receptors?

A

opens Na-K channels in ganglia and neuromuscular end plates

action is tissue dependent, e.g. vasoconstriction due to sympathetic innervation of blood vessels; increase motility and secretions due to parasympathetic postganglionic neuron discharge in the gut; muscle fasciculations and spasm due to neuromuscular end plate activation

36
Q

what kind of drug is rivastigmine, and what is it used to treat?

A

cholinesterase inhibitor (non-competitive, covalent but reversible)

used to treat mild/moderate Alzheimer’s disease

Neuro (50 decks)

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