Autonomics: Muscarinic antagonists

Question 1

atropine, homatropine, tropicamide

Answer 1

muscarinic antagonists

Clinical use: Produce mydriasis and cycloplegia; blocks muscarinic effects (DUMBBeLSS) of anticholinesterases but not the nicotinic effects

Adverse effects: ↑ body temperature (due to ↓ sweating); ↑HR;
dry mouth; dry, flushed skin; cycloplegia;
constipation; disorientation
Can cause acute angle-closure glaucoma in
elderly (due to mydriasis), urinary retention
in men with prostatic hyperplasia, and
hyperthermia in infants.

“Hot as a hare, dry as a bone, red as a beet, blind as a bat, mad as a hatter, full as a flask”

Question 2

Benztropine,

trihexyphenidyl

Answer 2

muscarinic antagonists

Clinical use: Parkinson disease (“park my Benz”).
Acute dystonia.

Question 3

glycopyrrolate

Answer 3

muscarinic antagonists

Clinical use: Parenteral: preoperative use to reduce airway
secretions.
Oral: drooling, peptic ulcer.

Question 4

hyoscyamine, dicyclomine

Answer 4

muscarinic antagonists

Clinical use: Antispasmodics for irritable bowel syndrome.

Question 5

ipratropium, tiotropium

Answer 5

muscarinic antagonists

Clinical use: COPD, asthma (“I pray I can breathe soon!”).

Question 6

Oxybutynin,
solifenacin,
tolterodine

Answer 6

muscarinic antagonists

Clinical use: Reduce bladder spasms and urge urinary
incontinence (overactive bladder).

Question 7

scopolamine

Answer 7

muscarinic antagonists

Clinical use: motion sickness