Cholinergic Agonists - Drugs Flashcards
Types of cholinergic drugs
Cholinergic agonist
Cholinergic antagonist
Types of cholinergic agonist
Direct acting and non-direct acting
What are direct acting cholinergic agents
- muscarinic agonist
- nicotinic agonist
Example of muscarinic agonists are
Pilocarpine
Bethanechol
Carbachol
Methacholine
(Chol)
Acetylcholine - ABC-MP
What are the indirect acting cholinomimetics
-reversible and irreversible
Reversible AchE inhibitors
Stigmines
Edrophonium
Tacrine
Donepezil
DETS
Irreversible AchE inhibitors
- OPC
- Melathion
- Parathion
- Echothiophate
OPEM : cause anticholinesterase poisoning
Bethanechol?
A direct acting muscarinic agonist which work mainly on
- increasing motility / contraction in GIT & UB respectively
- Congenital megacolon
- Xerostomia
Pilocarpine
A tertiary amine that binds to muscuranic agonist
Functions to reduce IOP for open and closed angle glaucoma (DOC) by constriction of the circular ciliary muscles and pupillary sphincter
It also stimulates sweat, tears and saliva
Xerostomia
S/e of pilocarpine
Apart of muscuranic effects it can lead to CNS effects of drowsiness and sedation
Because they cross bbb
Carbachol?
A direct acting cholmimetic which acts on both M and N receptors
Used for glaucoma via motic action
Can cause release of epinephrine from adrenal gland
Physostigmine
An indirect reversible cholinergic agonist
Act on GIT, UB and treat glaucoma
S/e: muscarinic effects and CNS effects (crosses bbb)
Does physostigmine cross bbb
Yes and cause CNS s/e
Neostgmine
Does not cross bbb
- Act on GIT: postoperative and neurogenic ileus
- UB retention
- an antidote for tubocurarine and other competitive NMJ blocking agent -myasthenia gravis
Which cholomimetic cross CNS
Physostigmine Pilocarpine OPC Donepezil Tacrine
Myasthenia gravis
- Loss of muscle on exertion but improves after rest
- affects mostly extraocular muscles, face muscles, swallowing muscles, chewing muscles.
- fist symptom is ptosis or diplopia
Mysthenia gravies tx
Pyridostigmine (doc for chronic cases)
Neostigmine
Edrophonium (for diagnosis)
Endrophonium has been replaced with anti-ACHr antibody
Use of Donepezil, tacrine, rivastigmine, galantamine
Treat Alzheimer’s disease (1st line)
By inhibiting the enzyme that destroys ach
Don Riva forgot to dance at the Gala
S\E of Donepezil
V/p/n/d
Liver damage =increased ALT
Tx of glaucoma
- Pilocarpine (DOC)
- cabarchol
- OPC : topical ointment
- physostigmine
Physostigmine overdose tx
- atropine
- phenothiazine
- TCA
all are anti cholinergics
What can you use to activate AchE
Pralidoxime via dephosphorylation if given early
Reversers the nicotinic effects of anticholinesterase poisoning
Contraindications of cholinergic agonists
Diarrhea GI or UB obstruction Pudx Bronchial asthma Hypotension Bradycardia
Symptoms of achE inhibitors toxicity
DUMBBELLS
Diarrhea Urination Miosis Bronchoconstriction Bradycardia Emesis Lacrimation Salivating Sweating
+ Nicotinic effects: NMJ blockage similar effects to succinylcholine
Substances used for AchE inhibitors toxicity
Atropine: cross bbb for CNS symptoms
Pralidoxime: does not cross bbb
Methacholine
It stimulates muscarinic receptors when inhaled.
A challenge test for the diagnosis of asthma
Reversible indirect cholinergic agonist that does not cross bbb
- neostigmine
- pyridostigmine
Cuz that have positive charge as a quaternary amine
What drugs do you give to Andre the s/e of pyridostigmine
- glycopyrrolate
- hyoscyamine
- propantheline
CNS effects of anticholinesterase poisoning
Lethargy, seizures, respiratory depression, coma
