Lecture 13 - Cholinergic Antagonists Flashcards by Raegan Chambers

What are the muscarinic antagonists? (six)

Atropine 
Scopolamine 
Glycopyrrolate 
Oxybutynin 
Ipratropium 
Tropicamide

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What are the non-depolarizing NMJ blocking agents? (five)

D-tubocurarine 
Pancuronium 
Vecuronium 
Cisatracurium 
Atracurium

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What are the depolarizing NMJ blocking agents? (one)

Succinylcholine

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What does atropine come from?

Belladona/nightshade

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What does scopolamine come from?

angels trumpet

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What is the general distribution of atropine?

Only gets into CNS with very high doses

Mostly peripheral effects

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About how long does atropine last in dogs?

30 min

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What is the general distribution of scopolamine?

CNS!

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What effects do you see with scopolamine?

Euphoria + Sedation + Amnesia

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What determines the effects of atropine at a certain organ?

Dose
Prevailing tone
Distribution of M receptors

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How do rabbits react to atropine?

Resistant, have special enzyme to metabolize quickly

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How do goats, cattle, and horses react to atropine?

Can eat the plant, but injected atropine can be VERY toxic

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How do swine react to atropine?

very sensitive, can’t even eat it

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What are the general CNS effects of atropine?

Confusion + Coma

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What are the toxic CNS effects of scopolamine?

Hallucinations + Delirium + Coma

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What is the normal state of the eye?

PNS - slightly rounded lens + slightly constricted pupil

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What does muscarinic antagonist do to the eye?

PNS decreased
Pupil dilated - via circular muscle
Lens flattens - via ciliary muscle

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What is mydriasis?

Dilation

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What is miosis?

Constriction

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What side effects do you see with muscarinic blocked in the eye?

Photophobia + Blurry vision + Dry eyes

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What type of muscarinic receptor is on the heart?

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What does M2 do at the heart?

ACh stimulates M2 on the heart at SA node
Pre-synaptic M2 decreases NE
Both decrease heart rate

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What does muscarinic blockade due to the heart?

Tachycardia

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When is atropine used in relation to the heart?

Cardiac arrest

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What do cholinergic antagonists do to respiration?

Reverse bronchoconstriction --or-- Bronchodilation

When is a cholinergic antagonist used in regards to respiration?

RAO or Heaves

What cholinergic antagonist is used for heaves?

Ipratropium

What does muscarinic blockade do in the GI tract?

Decrease motility + secretions | Decrease tone of bile duct

What does muscarinic blockade do to the bladder?

Decrease bladder motility | Decrease tone of ureter

What does muscarinic blockade do to the uterus?

Depress hypertonicity

What is a cholinergic antagonists used for during surgery?

Decrease secretions

What is a common side effect with cholinergic antagonists?

Dry mouth

What is the general effect of cholinergic antagonist in regards to secretions?

Dry eyes + Lack of sweating

What is used to reverse bradycardia in sx?

Atropine

What is used to prevent/treat post-operative bradycardia ?

Glycopyrrolate

What is something you have to watch out for with Glycopyrrolate?

Colic in horses

What is used for decreasing GI hypermotility + spasms?

Glycopyrrolate + Propantheline

What is used to decrease bladder activity + incontinence?

Oxybutynin

What is used to treat anterior uveitis?

Atropine

What is used in corneal ulceration treatment to decrease pain?

Atropine

What is used to cause mydriasis for intraocular exam?

tropicamide

How does tropicamide act differently in horses?

lasts for up to 12 hours

What is used to decrease respiratory secretions in surgery?

Atropine + Glycopyrrolate

What is used in treatment of organophosphate poisoning?

Atropine

What are the common side effects with cholinergic antagonists?

``` Dry mouth Decrease secretions Tachycardia with possible arrhythmias Mydriasis + Cycloplegia Decreased GI motility ```

What is the phrase for atropine overdose?

Dry as a bone Blind as a bat Mad as a hatter

What do you see with atropine overdose specifically?

``` Hot + Dry Constipated + Urinary retention Dilated pupils + blurred vision Tachycardia Aggitation + Delirum Cardiovascular + respiratory collapse ```

What is used to treat atropine overdose?

AChE inhibitors | Physostigmine to increase CNS ACh

What are the two types of Neuromuscular blockers?

Depolarizing -- and -- Non-depolarizing

What do the depolarizing NM blockers do?

Stimulate a muscular contraction before blocking the receptor

What do the non-depolarizing NM blockers do?

Competive antagonists | Direct blockade of channel occurs with no contractions

What are NM blockers used for?

paralysis with surgery

What is the onset of action for non-depolarizing NM blockers?

1 to 6 minutes

What is the distribution of non-depolarizing NM blockers in the CNS? Why?

Not able to get to CNS | Highly ionized

What can reverse non-depolarizing NM blockers?

Cholinesterase inhibitors to increase ACh levels enough to overcome blocker

What is the most common non-depolarizing NM blocker to use?

Atracurium

What is atracurium broken down by?

Plasma cholinesterase

How does cisatracurium compare to atracurium?

More potent | Less likely to cause histamine release

What are the long acting non-depolarizing drugs?

d-tubocurarine | pancuronium

What are the intermediate non-depolarizing drugs?

Vecuronium Atracurium Cisatracurium

What is the duration of the long action non-depolarizing drugs?

2 to 3 hours

What is the duration of the intermediate non-depolarizing drugs?

30 to 90 minutes

What is the progression of paralysis with the non-depolarizing drugs?

Small muscles Larger muscles Deglutition + Laryngeal + Abdominal intercostal muscles Respiratory muscles

How long does succinylcholine last?

5 ot 10 minutes

What is succinylcholine used for?

Short procedures

What animals are resistant to succinylcholine?

Horse + Pigs

What ion is important to watch out for with use of succinylcholine?

K+

What does succinylcholine do in regards to K+?

Increases release of K+, leading to hyperkalemia in dogs who are already sick = cardiac arrest

What effect does tetracylines + aminoglycosides have on ACh release?

Decreased | reverse with Ca but NOT neostigmine

What effect does Polymixins have on ACh?

Decrease post-synaptic sensitivity

What effect does clindamycin have on muscle?

Inhibits, cannot be reverse with Ca or neostigmine