Cholinergic Agonists and Antagonists

Question 1

Muscarinic Antagonists

Answer 1

Atropine

Question 2

Rx: organophosphate poisoning (insecticides and nerve gas),
induction of mydriasis and cycloplegia (though long duration of action)
reverse bradycardia of vagal origin
reverse gastrointestinal hypermotility
bladder spasms (urgency) associated
with cystitis

Toxicity: See Atropine poisoning

Answer 2

Atropine

Question 3

Highly toxic, used in very small doses
Rx: nausea and vomiting associated with motion sickness or chemotherapy
Tx: anti-muscarinic actions (see atropine poisoning), effects may be
long-lived especially in adults

Answer 3

Scopolamine

Question 4

Quaternary nitrogen muscarinic antagonist
Rx: used to protect against excessive muscarinic effects of cholinesterase inhibitors during reversal of neuromuscular blockade, pre-operative anti-salilogogue,
Tx: can cause heat stroke due to inability to sweat in heat

Answer 4

Glycopyrrolate

Question 5

Irreversible acetycholinesterase inhibitor used clinically

Rx: long-term miosis in the treatment of open angle glaucoma

Half-life is long, only requires 1x per day dosing (good for old people)

Answer 5

Echothiophate

Question 6

Treatment

Ventilation
Suction of tracheal secretions
Anti-muscarinic agent (atropine)
Reactivation of acetylcholinesterase
	with Pralidoxime Chloride (2-PAM)

Answer 6

Irreversible Cholinesterase Inhibitors

Organophosphates phosphorylate cholinesterases