Cholinergic & Anticholinergics

Question 1

What are the different type of Cholinergic receptors and which system do they represent?

Answer 1

Muscarinic
M1: stomach CNS, impt in nausea and vomiting pathways
M2: heart,CNS
M3: lungs, glands, GI tract, CNS, eyes
M4,M5: CNS

Nicotinic
N1 or Nm: skeletal muscle
N2 or Nn: ganglion,CNS

Question 2

What are the common adverse effects of cholinergic agonists

Answer 2

-Diarrhoea
-Diaphoresis
-Miosis
-Nausea
-Urinary urgency

Question 3

What are some general contraindications of cholinergic drugs?

Answer 3

Asthma
Peptic ulcer- cholinergic drugs can enhance gastric acid secretion

Question 4

What substance is a quaternary ammonium and does not cross membranes or BBB?

Answer 4

Acetylcholine

Question 5

Lists the uses and AE of Pilocarpine

Answer 5

M3 muscarinic receptor agonist;
use in Glaucoma and Xerostomia (dry mouth)
AE: CI in Asthma, COPD, sweating and burring vision

Question 6

List the uses and AE of Bethanechol

Answer 6

M3 muscarinic receptor agonist;
treatment for gastric atony after vagotomy (management of peptic ulcer), treatment of urinary retention (induce urination)
AE: CI in Asthma, nausea, vomiting, miosis

Question 7

List the uses and AE of Nicotine.

Answer 7

Nm and Nn nicotinic Ach receptor agonist;
aid to smoking cessation
AE: Peripheral vasoconstriction (sympathetic); Gut hypermobility (parasympathetic) Both sympathetic and parasympathetic is activated; different system has different priority

Question 8

List the uses and AE of Varenicline

Answer 8

Partial nicotinic agonist
aid to smoking cessation
associated with psychiatric symptoms (suicidal ideation)

Question 9

How do indirect cholinergic drugs work?

Answer 9

They inhibit the action of acetylcholinesterase (AChE) which breakdowns Ach –> increasing Availability of acetylcholine.

Question 10

List the uses and AE of Donepezil

Answer 10

AChE inhibitor
crosses BBB easily; use in Alzheimer’s disease (promotes modest cognitive improvement)
AE: nausea, vomiting and other common cholinergic side effects

Question 11

List the uses and AE of Physostigmine

Answer 11

AChE inhibitor
crosses BBB easily; use as antidote for atropine poisoning
AE: nausea, vomiting and other common cholinergic side effects

Question 12

Describe the pathophysiology of myasthenia gravis.

Answer 12

Myasthenia gravis is an autoimmune disease in which antibodies attack the Nm nAChRs at the neuromuscular junctions. Muscles cannot contract due to the lack of Ach Signal due to destroyed receptors

Question 13

List the uses and AE of Neostigmine

Answer 13

AChE inhibitor
treatment for Myasthenia gravis; reversal of nondepolarizing neuromuscular blockade
AE: poor CSF penetration so no nausea; diarrhea, seating and urinary urgency

Question 14

List the AE and antidote of Sarin

Answer 14

Organophosphate agent; suicide AChE inhibitor (effects are very long lasting)
Acute poisoning:
SLUD: Salivation, Lacrimation, Urination, Defecation
Also: Coma, Seizure, nausea, Bradycardia

Antidote: Cholinesterase regenerator (Pralidoxime)
mACh receptor block (atropine)

Question 15

What must be taken into account when administering pralidoxime for acute Sarin poisoning?

Answer 15

Must be administered within a few hours before “ageing” (further chemical reaction that make the inhibition irreversible.

Question 16

What are some adverse effects of muscarinic antagonism?

Answer 16

Urinary retention, constipation, mydriasis (dilation of eyes), confusion, blurred vision

Question 17

List the type , uses and AE of Atropine.***

Answer 17

Nonselective muscarinic Ach receptor antagonist.
Uses: treatment of bradycardia (increase heart rate), treatment of anticholinesterase overdose, GI antimotility to treat diarrhea.
AE: “red as a beet, blind as a bat, dry as a bone, hot as a hare, mad as a hatter”: superficial vasodilation, blurred vision, decreased secretions, hyperthermia, hallucinations
CI in Narrow-angle glaucoma (increase intraocular pressure)

Question 18

List the type, uses and AE of Benzatropine

Answer 18

Nonselective M receptor antagonist
Crosses BBB and has stronger CNS effect
Uses: Parkinson’s disease: second or third line therapy
AE: hyperthermia due to decrease sweat, glaucoma, urinary retention, dry mouth, constipation, hallucination, sedation
CI in Narrow-angle glaucoma (increase intraocular pressure)

Question 19

List the type, uses and AE of Scopolamine (hyoscine)

Answer 19

Nonselective muscarinic Ach receptor antagonist.
Uses: motion sickness, adjunct for anaesthesia, urinary incontinence
AE: Dry mouth, urinary retention , sedation , glaucoma
CI in Narrow-angle glaucoma (increase intraocular pressure)

Question 20

List the type, uses and AE of Ipratropium

Answer 20

Nonselective muscarinic Ach receptor antagonist.
M3 Effect: Decrease bronchoconstriction and bronchial secretion
Uses: COPD and asthma
AE: decrease GI motility , tachy, mydriasis
CI in Narrow-angle glaucoma (increase intraocular pressure)

Question 21

List the type, uses and AE of Oxybutynin

Answer 21

Nonselective muscarinic Ach receptor antagonist.
M3 Effect: relax smooth muscle walls, increase sphincter tone and decrease secretions
Uses: urinary incontinence
AE: decrease GI motility , tachy, mydriasis
CI in Narrow-angle glaucoma (increase intraocular pressure), Ci in pyloric obstruction, retentive bladder (cannot empty all your urine)

Question 22

What happens when u give nicotine in high doses?

Answer 22

Induce Depolarizing blockade; induce medullary depression as all ganglionic nicotinic receptor are blocked

Question 23

What indirect anticholinergic drug is a depolarizing neuromuscular blocking agent? How does it work and what does it cause?

Answer 23

Succinylcholine
Causes twitching initially ,followed by flaccid paralysis
use for paralysis in surgical procedures.
* cannot be reversed by tetanic stimulation or cholinesterase inhibitor

Question 24

What direct anticholinergic drug is a non-depolarizing neuromuscular blocking agent? How does it work and what does it cause?

Answer 24

Pancuronium
Competitive antagonist of Nm Nicotinic acetylcholine receptor
- non depolarizing blockade results in skeletal muscle paralysis
Uses: induction of paralysis for surg
AD: histamine release
* can be reversed by tetanic stimulation or cholinesterase inhibitor

Question 25

What indirect anticholinergic drug is a inhibitor of vesicular exocytosis? How does it work and what does it cause?

Answer 25

Botulinum Toxin (BOTOX)
Mechanism: prevent exocytosis of ACh containing synaptic vescles
Uses: paralysis certain muscle
Side effect: allergic reaction