Autonomics III: Cholinergic Receptor Inhibitors

Question 1

Benzotropine: Application & Mechanism

Answer 1

Parkinson’s; block of muscarinic receptors

Question 2

Scopolamine: Application & Mechanism

Answer 2

Prevent or reduce motion sickness; block of muscarinic receptors

Question 3

Atropine and tropicamide: Application & Mechanism

Answer 3

Produce mydriasis and cycloplegia; block of M3 receptors

Question 4

Ipratropium and tiotropium: Application & Mechanism

Answer 4

Cause bronchodilation in asthma COPD; block of M3 receptors

Question 5

Dicyclomine: Application & Mechanism

Answer 5

Reduces transient hypermotility; block of M1 &M3 receptors

Question 6

Tolterodine: Application & Mechanism

Answer 6

Treats transient cystitis, postop bladder spasms, incontinence; block of M3 receptors

Question 7

Why is atropine used for someone poisoned with cholinesterase inhibitors and mushrooms?

Answer 7

Tertiary amine, interacts well with both CNS and peripheral muscarinic receptors

Question 8

Overdose with muscarinic antagonists causes what symptoms?

Answer 8

“Dry as a bone, blind as a bat, red as a beet, mad as a hatter”

Question 9

Hexamethonium & mecamylamine: Application & Mechanism

Answer 9

Field surgery, Tourette’s and nicotine craving amelioration (mecamylamine); ganglionic blockers that competitively inhibit Nn receptors at both para and symp ganglia.

Question 10

Toxic effects of NMJ blockers? Cholinesterase inhibitors are effective at blocking the effects of what NMJ blockers, and what NMJ blocker’s effect is perhaps increased by these?

Answer 10

Respiratory paralysis and disturbance of autonomic function (some interaction with Nn). Non-depolarizing blockers’ effect blocked, depolarizing block unaffected or even increased.

Question 11

Tubocurarine & mivacurium: Application & Mechanism

Answer 11

Muscle relaxation to facilitate surgery; non-depolarizing competitive antagonists at Nm

Question 12

Succinylcholine: Application & Mechanism

Answer 12

For brief procedures like tracheal intubation; depolarizing blocker at Nm, causes initial contraction then flaccid paralysis. Acts a little bit at Nn too.

Question 13

Botulinum toxin type A: Application & Mechanism

Answer 13

Reduces frown lines and wrinkles, achalasia, strabismus, and oromandibular dystonia; degrades SNAP-25 that mediates fusion of presynaptic vesicles at terminal.