Lecture 38 - Cholinergic agonists Flashcards
what would be the anticipated effect following administering an anticholinergic drug to an animal?
a. hypoxemia
b. hypotension
c. GI ileus
d. miosis of the pupil
c. GI ileus
what species is least likely to respond to the effects of atropine when administered intravenously
a. dogs
b. horses
c. goats
d. rabbits
d. rabbits
a veterinarian performs an abdominal surgery on a dog under general anesthesia. the heart rate drops from 90 bpm to 40 bpm due to vagal stimulation. which drug is the best choice to administer?
a. atropine
b. acetylcholine
c. ipratropium
d. atenolol
a. atropine
too much cholinergic activity results in
- diarrhea
- urination
- miosis
- bronchoconstriction/bradycardia
- emesis
- lacrimation
- lethargy
- salivation, secretions, sweating
inidrect acting drugs do what
increase ACh
what are direct-acting cholinergic agonists
- acetylcholine
- bethanechol
- pilocarpine
- toxic muchrooms
describe bethanechol
- direct muscarinic agonist (M3 selectivity)
- acts by stimulating smooth muscle (increases GI motility, urinary bladder detrusor m. contractility)
- oral, injectible
what contradictions and toxicity are there in bethanechol use
Contradictions = GI obstruction, urethral obstruction
toxicity = DUMBELLS, severe rxn when given IV/IM
describe pilocarpine
tx ocular disorders (glaucoma, neurogenic KCS)
what are toxic indirect-acting parasympathomimetics
- organophosphates
- Anticholinesterases
what are therapeutic indirect-acting parasympathomimetics
- edrophonium
- pyridostigmine
- neostigmine
- physostigmine
why are organophosphates and anticholinesterases toxic
irreversible inhibition of Ach-E and easily absorbed
what clinical uses do edrophonium, pyridostigmine, and neostigmine have
- increase Ach at neuromuscular junction
- diagnose and manage myasthenia gravis
- treat rumen atony/GI ileus
- reverse neuromuscular blocks in anesthesia
____ has rapid onset, short action whereas ____ has slow onset, long action
edrophonium; pyridostigmine
