Drugs acting on the PSNS Flashcards
Can parasympathomimetic drugs that affect the PSNS be direct acting or indirect acting?
Parasympathomimetics can be BOTH
Can parasympatholytic drugs be directing acting or indirect acting?
Direct acting
What is a drug that is a DIRECT acting parasympathomimetic?
Bethanechol
How is Bethanechol typically administered?
PO
What drug is frequently used to increase bladder contractility?
Bethanechol
What drug has indications such as:
Increase GI motility
Treat dysautonomia
Increase bladder contractility
Reproductive case?
Bethanechol
What are some cautions indicated with Bethanechol?
must have patent urethra and intact bladder wall
Do not use if GI obstruction is present
With overdose, typically see excessive muscarinic signs
What kind of agonist is Bethanechol? (muscarinic or nicotinic?
Muscarinic with some selectivity for M3 receptors
What are some INDIRECT acting Parasympathomimetics that are reversible anticholinesterases?
Neostigmine
Pyridostigmine
Edrophonium
What ways can Neostigmine be administered?
Oral tablets or injectable
How long does it take for Neostigmine to take affect?
10-30 minutes and lasts 4 hours (in humans)
What are some indications for Neostigmine?
Treatment of rumen atony (not used much)
Stimulate GI motility and bladder emptying
Reversal of competitive neuromuscular blockers **
Treatment of MG in dogs
What two Indirect acting parasympathomimetics can be used to treat Mysathenia Gravis in dogs? Which one is used more frequently? Why?
Neostigmine and Pyridostigmine
You use Pyridostigmine more because its effects last longer than Neostigmine
What is the indication for Pyridostigmine?
Treatment of Myasthenia Gravis in dogs
In what ways can you administer pyridostigmine?
Oral tablets, ER tablets, oral syrup, injectable
How is Edrophonium administered?
10 mg/mL solution for injection
Is Edrophonium fast acting or slow acting?
Very fast acting: Onset 1 minute, lasts around 10 minutes
What drug has indications such as:
Tensilon test for MG
Differentiate MG from cholinergic crisis
Reversal of nondepolarizing NMBs
Edrophonium
What drug is used to differentiate MG from a cholinergic crisis?
Edrophonium
What are drugs that are INDIRECT acting parasympathomimetics and are irreversible anticholinesterases?
Echotiophate (ophthalmic) Organophosphate insecticides (toxicity)
What are the muscarinic effects of Organophosphate toxicity?
DUMBBELS
Diarrhea Urination Miosis Branchospasm Bradycardia Emesis Lacrimation Salivation
What are the nicotinic effects of organophosphate toxicity?
Muscle tremors
Muscle weakness
Muscle paralysis
What are some DIRECT acting parasympatholytic drugs? And what do they act as?
Atropine
Glycopyrrolate
Oxybutynin
Propantheline
Act as muscarinic antagonists
Will have sympathetic signs
What are some effects of Atropine?
tachycardia mydriasis dries secretions reduces salivation slows gut bronchodilation blurred vision difficulty with urination
What is Atropine sulfate available as?
Injectable solution and oral tablets, but typically used as an injection
What is the main indication for Atropine?
Treatment of Bradyarrhthmias/bradycardia
What drug has indications such as:
Treatment of organophosphate and carbamate toxicity
Treatment of bradarrhythmias/bradycardia
Treatment of cholinergic crisis/anticholinesterase overdose
Atropine to the rescue!
What animal has endogenous atropinases and will break down Atropine very rapidly
Rabbits
What are some cautions to take into account with Atropine?
Contraindicated in glaucoma, tachycardia
Certain GI diseases, obstructive uropathy, MG
Rabbits
What two Direct acting parasympatholytic is used as a GI or urinary antispasmodic agent?
Oxybutynin and Propantheline
Does Oxybutynin or Propantheline readily cross the BBB?
Oxybutynin is widely distributed and crosses the BBB where as Propantheline does not readily cross the BBB
What is the indication for Oxybutynin and Propantheline?
Incontinence due to detrusor muscle instability (hyperactive bladder)
