Muscarinic Receptor Antagonist

Question 1

Atropine
MOA

Answer 1

Competitive non-specific reversible antagonism at all muscarinic receptors.
Inhibits secretions (salivary, bronchial, sweat, gastric acid, etc.).
Tachycardia.
Relaxes smooth muscle (causing inhibition of peristalsis, pupillary dilation, paralysis of accommodation, etc.).
Antiemetic (CNS e‚ect).

Question 2

Atropine
Abs/Distrb/Elim

Answer 2

Given orally. Half-life 3h.

Question 3

Atropine
Clinical use

Answer 3

Paralysis of accommodation and pupil dilation for eye examination (tropicamide). Urinary
incontinence (oxybutinin). Irritable bowel syndrome (dicycloverine). Antidote for anticholinesterase
poisoning. Treatment of cardiac slowing.

Question 4

Atropine
Adverse effects

Answer 4

Constipation, hyperthermia (reduced sweating), dry mouth, urinary retention, blurred vision, raised
intraocular pressure, CNS excitement (delerium, hallucinations).