Section 2d Cholinergic Antagonists

Question 1

Where do antimuscarinic agents work?

Answer 1

parasympathetic nerves ONLY

Question 2

Where do Nn blockers work?

Answer 2

sympathetic and parasympathetic

Question 3

What Cholinergic receptor does Atropine have high affinity for?

Answer 3

muscarinic - in CNS and PNS - lasts about 4 hours, and days if used topically

Question 4

How does the dose of Atropine effect the body?

Answer 4

at low doses it slows the heart (presynaptic effects), then high doses increase heart rate (postsynaptic effects), and really high doses lead to hallucinations; delirium; coma (biphasic on the heart)

Question 5

What does Atropine do to the eye?

Answer 5

induces mydriasis, increases IOP

Question 6

What does Atropine do to in the smooth muscle of the lungs and gut?

Answer 6

lung = it prevents reflex bronchoconstriction - thus bronchodilation and reduce airway resistance
gut = reduces tone and contraction of stomach and intestine

Question 7

What are Atropines effects of sweating? and what are the repercussions?

Answer 7

sweating is prevented – thus with no sweat cooling down the body this can lead to atropine fever

Question 8

what is possible with slow heart rate?

Answer 8

arrhythmias

Question 9

What can be used to overcome atropine toxicity?

Answer 9

physostigmine

Question 10

What is tropicamide?

Answer 10

similar to atropine, but shorter acting and mainly used for short acting mydriasis

Question 11

What cholinergic antagonist is used for motion sickness and nausea due to chemotherapy? (antiemetic) and how does the duration of action compare to atropine? and adverse effects?

Answer 11

Scopolamine (hyoscine hydrobromide); longer acting that atropine
Adverse effects = sedation and dry mouth

Question 12

What is Methoscopolamine used for?

Answer 12

muscarinic antagonist used to decrease oral secretion, treat PEPTIC ULCER DISEASE and decrease GI spasm

Question 13

What is Glycopyrrolate used for?

Answer 13

muscarinic antagonist used to prevent bradycardia during surgical procedures

Question 14

What is Ipratropium used for?

Answer 14

muscarinic antagonist used in treating asthma in patients unable to take adrenergic agonists – useful in management of COPD - requires nebulizer

Question 15

what is Tiotropium used for?

Answer 15

similar to ipratropium but has recently shown superior efficacy to ipratropium in treatment of COPD

Question 16

What is cyclopentolate used for? and adverse effects?

Answer 16

muscarinic antagonist used as a short acting mydriasis (useful for eye exams) and cycloplegia –> increases IOP, blurred vision, irritation (all adverse effects)

Question 17

What is cycloplegia?

Answer 17

paralysis of the ciliary muscle in the eye (does not allow focusing) - helps dilate the pupil for eye examinations

Question 18

For cyclopentolate and tropicamide, which would you use for adults and children?

Answer 18

cyclopentolate for children

tropicamide for adults

Question 19

Common adverse effects for cholinergic antagonists

Answer 19

blurred vision, confusion, dilated pupils, constipation, urinary retention