Pharm - Autonomic Drugs (Cholinomimetic agents & Cholinesterase inhibitor poisoning)

Question 1

Name 4 direct cholinomimetic agonists.

Answer 1

(1) Bethanechol (2) Carbachol (3) Pilocarpine (4) Methacoline

Question 2

What are 3 clinical applications for Bethanechol?

Answer 2

(1) Postoperative ileus, (2) Neurogenic ileus, and (3) Urinary retention

Question 3

What is the action of Bethanechol?

Answer 3

Activates bowel and bladder smooth muscle; Think: “BETHANy, CALL (bethanechol) me, maybe, if you want to activate your Bowels and Bladder.”

Question 4

What effect does AChE have on Bethanechol?

Answer 4

Resistant to AChE

Question 5

What are 3 clinical applications for Carbachol?

Answer 5

(1) Glaucoma, (2) Pupillary constriction, and (3) Relief of intraocular pressure

Question 6

What is the action of Carbachol?

Answer 6

“CARBon copy of AcetylCHOLine”

Question 7

What are 2 categories of clinical use for Pilocarpine?

Answer 7

(1) Potent stimulator of sweat, tears, and saliva (2) Open-angle and Close-angle glaucoma; Think: “you cry, drool, and sweat on your ‘PILOw’”

Question 8

What are the 2 actions of Pilocarpine, and to which clinical applications is each related?

Answer 8

(1) Contracts ciliary muscle of eye (open-angle glaucoma), (2) Pupillary sphincter (closed-angle glaucoma)

Question 9

What is the clinical use for Methacholine?

Answer 9

Challenge test for diagnosis of asthma

Question 10

What is the action of Methacholine?

Answer 10

Stimulates Muscarinic receptors in airway when inhaled

Question 11

What is another name for indirect cholinomimetic agonists? List 5 examples.

Answer 11

Indirect cholinomimetic agonist (anticholinesterases); (1) Neostigmine (2) Pyridostigmine (3) Physostigmine (4) Donepezil, Rivastigmine, Galantamine (5) Edrophonium

Question 12

What are 4 clinical uses for Neostigmine?

Answer 12

(1) Postoperative and neurogenic ileus and (2) Urinary retention, (3) Myasthenia gravis, (4) Reversal of neuromuscular junction blockade (postoperative)

Question 13

What is the action of Neostigmine?

Answer 13

Increase endogenous ACh

Question 14

Does Neostigmine penetrate the CNS?

Answer 14

No CNS penetration; Think: “NEO CNS”

Question 15

What is a clinical application for Pyridostigmine?

Answer 15

Myasthenia gravis (long acting); Think: “pyRIDostiGMine gets RID of Myasthenia Gravis”

Question 16

Does Pyridostigmine penetrate the CNS?

Answer 16

Deos not penetrate CNS

Question 17

What are 2 actions of Pyridostigmine?

Answer 17

Increase endogenous ACh; Increase strength

Question 18

What is a clinical application for Physostigmine?

Answer 18

Anticholinergic toxicity (crosses blood-brain barrier => CNS); Think: “PHYsostigmine ‘PHYxes’ atropine overdose”

Question 19

Does Physostigmine penetrate the CNS?

Answer 19

Crosses blood-brain barrier => CNS

Question 20

What is a clinical application of Donepezil? What other 2 drugs have the same application?

Answer 20

Alzheimer disease; Donepezil, Rivastigmine, Galantamine

Question 21

What is the action of Donepezil? Again, what other 2 drugs have this same action?

Answer 21

Increase endogenous ACh; Donepezil, Rivastigmine, Galantamine

Question 22

What is a historical clinical application of Edrophonium? Why is it considered to be historical?

Answer 22

Historically, diagnosis of myasthenia gravis (extremely short acting). Myasthenia now diagnosed by anti-AChR Ab (anti-acetylcholine receptor antibody) test.

Question 23

What is the action of Edrophonium?

Answer 23

Increase endogenous ACh

Question 24

What are 3 complications that should be watched for with use of all cholinomimetic agents in susceptible patients?

Answer 24

With all cholinomimetic agents, watch for exacerbation of COPD, asthma, and peptic ulcers when giving to susceptible patients

Question 25

What group of drugs/substances often cause cholinesterase inhibitor poisoning, and why? Give an example of such a drug.

Answer 25

Often due to organophosphates, such as Parathion, that irreversibly inhibit AChE

Question 26

What are 9 symptoms associated with cholinesterase inhibitor poisoning?

Answer 26

Causes (1) Diarrhea, (2) Urination, (3) Miosis, (4) Bronchospasm, (5) Bradycardia, (6) Excitation of skeletal muscle and CNS, (7) Lacrimination, (8) Sweating, and (9) Salivation. Think: “DUMBBELSS”

Question 27

In what patient population is cholinesterase inhibitor poisoning usually seen, and why?

Answer 27

Organophosphates are components of insecticides; poisoning usually seen in farmers

Question 28

What is the antidote for cholinesterase inhibitor poisoning? Explain the mechanism of each component.

Answer 28

Antidote - Atropine (competitive inhibitor) + Pralidoxime (regenerates AchE if given early)