Cholinomimetics and Muscarinic Antagonists

Question 1

Bretylium and Guanethidine MOA

Answer 1

Blocks the release of norepinephrine from the nerve terminals

Question 2

Reserpine MOA

Answer 2

blocks neurotransmitter packaging into vesicles, thus lowering functional transmitter release (e.g., of NE) into the synapse

Question 3

Amphetamine, ephedrine MOA

Answer 3

augment the release of the patient’s norepinephrine from the nerve terminals

Question 4

Metyrosine MOA

Answer 4

Inhibits the conversion of tyrosine to DOPA, which consequently reduces the levels of dopamine and norepinephrine in the body.

Question 5

Vesamicol MOA

Answer 5

Prevents the uptake of ACh into presynaptic vesicles, decreasing ACh activity

Question 6

Hemicholinium MOA

Answer 6

Reduces the synthesis and level of ACh by blocking the uptake of choline, a building block of ACh, into presynaptic neurons

Question 7

Name four direct cholinergic agonists.

Answer 7

Bethanechol, carbachol, pilocarpine, and methacholine

Question 8

Bethanechol uses?

Answer 8

Postoperative and neurogenic ileus, urinary retention (Bethany, call [bethanechol] me if you want to activate your bowels and bladder)

Question 9

In a patient with glaucoma, what are two direct agonist cholinomimetic drugs that can be prescribed?

Answer 9

Carbachol (carbon copy of acetylcholine) and pilocarpine

actions on ciliary muscle and pupillary sphincter (M3)

Question 10

You suspect that your patient has asthma and plan to perform a challenge test. What is the agent of choice, and how does it work?

Answer 10

Methacholine—when inhaled, it stimulates muscarinic receptors in the airways and induces bronchoconstriction

Question 11

7 indirect cholindergic agonists

Answer 11

Neostigmine, pyridostigmine, edrophonium, physostigmine, donepezil, rivastigmine, & galantamine

Question 12

Neostigmine uses?

Answer 12

Postoperative and neurogenic ileus and urinary retention, myasthenia gravis, reversal of neuromuscular junction blockade (postoperative)

Question 13

In a patient with signs of myasthenia gravis, which anticholinesterase can you use to confirm your diagnosis? Why?

Answer 13

Edrophonium; the effects last for minutes, and if weakness is transiently reversed, it is diagnostic of myasthenia gravis

Question 14

You accidentally overdose a patient with atropine. What pharmacologic agent should you use to fix your mistake? Why?

Answer 14

Physostigmine; it can cross the blood-brain barrier and reverse central and peripheral nervous system effects (phyxes atropine overdose)

Question 15

Why is pyridostigmine used to treat myasthenia gravis?

Answer 15

Increases endogenous acetylcholine and muscle strength and is long acting and does not penetrate the CNS

Question 16

A patient has Alzheimer disease. What cholinomimetic agents can be prescribed for his treatment?

Answer 16

Donepezil, rivastigmine, galantamine

Question 17

You administer an anticholinesterase to an Alzheimer’s patient. What are some conditions that could be exacerbated by this class of agent?

Answer 17

COPD, peptic ulcers, and asthma

Question 18

Antidote to organophosphates

Answer 18

Atropine (competitive inhibitor) + pralidoxime (regenerates AChE)

Question 19

An elderly patient takes benztropine but cannot remember why. What is the likely clinical application and mechanism of action?

Answer 19

Benztropine, a muscarinic antagonist, is used to ease cholinergic symptoms of Parkinson disease (park my Benz) and to treat acute dystonia

Question 20

A patient’s severe asthma attack is unresponsive to albuterol. What other medications that act as muscarinic antagonists can be used?

Answer 20

Ipratropium and tiotropium are muscarinic antagonists used to treat asthma and COPD (I pray I can breathe soon)

Question 21

What is the mechanism and clinical application for oxybutynin, solifenacin, and tolterodine?

Answer 21

Muscarinic antagonists used to ease bladder spasms and relieve urge urinary incontinence (overactive bladder)

Question 22

A patient is administered glycopyrrolate parenterally before surgery. What is the effect of this agent? What if it’s given orally?

Answer 22

Muscarinic antagonist used to reduce airway secretions. If given orally, to treat peptic ulcers.

Question 23

A patient complains of motion sickness. What muscarinic antagonist is most commonly used for treatment?

Answer 23

Scopolamine

CNS penetration

Question 24

A patient is found to have irritable bowel syndrome. Which muscarinic antagonists can be prescribed as antispasmodics for this patient?

Answer 24

Hyoscyamine, dicyclomine

Question 25

Jimson weed (Datura)

Answer 25

gardener’s pupil (mydriasis due to plant alkaloids)

Don’t get confused with organophosphates