Cholinergic Agents

Question 0

What is selectivity?

Answer 0

The degree to which a drug preferentially binds to a receptor subtype

Question 1

At recommended doses, which drug is relatively selected for muscarinic receptors in the detrusor muscle of the urinary bladder and intestinal wall?

Answer 1

Bethanechol (Urecholine)

Question 2

The internal urethral sphincter is under which type of control

Answer 2

Sympathetic

Question 3

What type of receptor is found the internal urethral sphincter

Answer 3

Alpha-1

Question 4

Which nerve innervates the external urethral sphincter? Sympathetic nerve? PS nerve?

Answer 4

Pudendal external
Symp hypogastric n.
PS pelvic n.

Question 5

What types of receptors are found on the detrusor muscle

Answer 5

Beta-2 and muscarinic

Question 6

Carbamylcholine

Answer 6

Mostly used uterine contractions pigs. Selective intestinal wall. Not a lot small animal. Gi atony.

Question 7

Pilocarpine

Answer 7

Primary indication is to stimulate gland secretions. Decreases IOP. GIVE LOW dose because worry SLUD effects

Question 8

Metaclopramide

Answer 8

Anti emetic. Promotes gastric motility. KCS

Question 9

Edrophonium drug class, trade name, function

Answer 9

Tensilon, competitive reversible indirect acting cholinergic agent.

Bind to ACHE so that ACH can’t bind and get broken down

Prevent ach degradation, allows increased ACH bind to the few receptors left. Dx myasthenia gravis

Question 10

Pyridostigmine trade and purpose

Answer 10

Mestinon, tx myasthenia gravis, maintenance

Question 11

Physostigmine indications and drug class and toxic effects

Answer 11

Anticholinesterase or indirect acting cholinergic agent

Decrease IOP by causing miosis
Breakdown posterior synechia in horses
Treat gi atony in cattle subq

Can cross BBB since it’s non-ionized
Resp paralysis, vomiting, CNS depression, PS effects basically

Question 12

How do you irreversible indirect acting cholinergic agents work

Answer 12

They covalently bonded to acetylcholinesterase permanently inactivating it

Organophosphates

Question 13

Talk about major factors of organophosphate toxicities

Answer 13

Can cross blood brain barrier. Bronco constriction, airway secretions increased, abdominal cramping because of motility overdrive. Muscle tremors through the neuromuscular junction eventually lead to flaccid paralysis. This includes skeletal muscle needed to breathr. This leads to respiratory failure.

Question 14

Name two agents to counteract irreversible ACHesterases. Talk about their mechanism of action

Answer 14

Pralidoxime tradename 2Pam it breaks the bonds between acetylcholinesterase and organophosphate. It binds to the organophosphate so that the body can eliminate it.This frees up ACHE to work again. Atropine is palliative care counters the intense parasympathetic affects

Question 15

Atropine drug class and mechanism of action in treating ____ toxicity

Answer 15

Muscarinic receptor antagonist. @rec doses, It binds to cholinergic receptors until the body can eliminate organophosphates causing excess ACH

Question 16

Anti-cholinergic effects usually referred to which type of agents?

Answer 16

Cholinergic receptor antagonists

Question 17

Talk about atropine’s affects on the eye

Answer 17

It is often used for its cycloplegic effect. It relaxes the ciliary muscle. It inhibits parasympathetic innervation and there is unopposed sympathetic effect.

Question 18

What are the parasympathetic affects on the ciliary muscle?

Answer 18

Causes the ciliary muscle to contract. The ciliary muscle is attached to the lens.It makes the lens into a CONE shape and puts the focal point in the near field.

Question 19

What happens as a result of muscarinic antagonist at the ciliary muscle?

Answer 19

It relaxes the ciliary muscle. Lens flatten, and the focal point is in the distance. Common side effect is it blurry near vision

Question 20

Does atropine cause the mydriasis or miosis? What does muscle does it affect?

Answer 20

It causes pupil dilation. unopposed sympathetic stimulation at the dilator muscle

Question 21

Which cranial nerve carries parasympathetic innervation to the cranial organs

Answer 21

10

Question 22

What is the effect at the AV node mediated by cholinergic and adrenergic receptors? What types of receptors?

Answer 22

Speed of conduction. Muscarinic and beta-1

Question 23

What types of receptors are found on the heart? What is the effect at the SA node?

Answer 23

Muscarinic and beta-1. Heart rate

Question 24

What type of agent should you use if you think that increased vagal tone is the source of the problem

Answer 24

Anti-cholinergic agents to block excess vagal tone

Question 25

What should you give if you have a severe sinus bradycardia and decreased blood pressure? Under anesthesia

Answer 25

Atropine or glycopyrrolate

Question 26

Anti-cholinergic agents are used with extreme caution in which species? Why?

Answer 26

Horses because it can cause ileus. Doesnt like in rabbits or ruminants. And ruminant CNS toxicities are common and there is potential for rumen stasis which can be fatal

Question 27

Name an anticholinergic took that can cross the blood brain barrier and

Answer 27

Atropine

Question 28

Name some CNS signs that can be seen as atropine

Answer 28

Anxiety restlessness disorientation

Question 29

What drug is a good anti-cholinergic for C-sections? What makes it a good choice

Answer 29

Glycopyrrolate tradename Robinul-V. It’s more polar than atropine so it’s not going to cross the blood brain or placental barrier easily. It may be less likely to cause tachycardia

Question 30

What kind of drug would you use to counteract an overdose of atropine and glycopyrrolate? Why

Answer 30

The problem is the inhibition of parasympathetic effects. You want to increase parasympathetic affects so you’re going to try to initiate an ACH flood so that it can compete for cholinergic receptors and overcome inhibition. You would use an anti-acetylcholinesterase

Question 31

Name three endogenous catecholamines and 2 exogenous catecholamines

Answer 31

Endo norepinephrine epinephrine and dopamine. EXO isoproterenol and dobutamine