pharmacology: cholinergic drugs Flashcards
(31 cards)
where are M2 receptors? what is their mechanism?
SA and AV node
Gi coupled; decreased cAMP
where are the M1 receptors? M3 receptors? what is their mechanism?
M1: glands in the GI tract
M3: everywhere else essentially
Gq coupled: increased phospholipase C –> increased IP3, DAG, and Ca2+
botulinum toxin mechanism
interacts with synpatobrevin and other proteins to prevent ACh release - used in blepharospasm, strabismus/hyperhydrosis, dystonia, cosmetics
what has no innervation but has M3 receptors? what are the implications of this?
blood vessels - M3 leads to NO release (vasodilation)
means there will be no effects of indirect agonists
what are the muscarinic agonists?
Ach, bethanechol, methacholine, pilocarpine
Ach clinical uses
short half-life so no clinical use
bethanechol clnical use
ileus (postop/neurogenic), urinary retention
methacholine clinical uses
diagnositic procedure - bronchial hyperreactivity
pilocarpine use
topically used for glaucoma, xerostomia
what receptors can cause flaccid paralysis?
NN and NM because desensitized very quickly
NN and NM mechanisms
activation (opening) of Na/K channels
what are the indirect-acting cholinomimetics?
acetylcholinesterase inhibitors:
edrophonium, physostigmine, neostigmine, pyridostigmine, donepezil, organophosphates (echothiphate, malathion, parathion)
edrophonium: characteristics and clinical uses
characteristics : short acting
clinical uses: diagnose myasthenia and used to differentiate myasthenia from cholinergic crisis (desensitization)
physostigmine: characteristics and clinical uses
characteristics: tertiary amine (enters CNS)
clinical uses: glaucoma, antidote in atropine overdose
neostigmine and pyridostigmine: characteristics and clinical uses
characteristics: quaternary amines (no CNS entry)
clinical uses: ileus, urinary retention, myasthenia, reversal of nondepolarizing NM blockers
donepezil: characteristics and clinical uses
characteristics: lipid soluble (CNS entry) - oral form!!
clinical uses: alzheimer’s
organophosphates (echothiophate, malathion, parathion, sarin): characteristics and clinical uses
characteristics: lipid-soluble, IRREVERSIBLE INHIBITORS (non competitive)
clinical uses: glaucoma (echothiophate eyedrops)
insecticides (malathion, parathion), nerve gas (sarin)
where can acetylcholinesterase inhibitors NOT be used?
blood vessels
acute toxicity of AChE inhibitors
excessive muscarinic and nicotinic stimulations
muscarinic effects: diarrhea, urination, miosis (pinpoint pupil), bradycardia, bronchoconstriction, lacrimation, salivation, sweating, CNS stimulation
nicotinic effects: skeletal muscle excitation followed by paralysis (cholinergic crisis), CNS stimulation
management of AChE inhibitors
atropine (muscarinic blocker); regeneration of AChE: pralidoxime (2-PAM)
chronic toxicity of AChE inhibitors
peripheral neuropathy causing muscle weakness and sensory loss d/t demyelination not due to AChE inhibitors (no treatment)
what are the muscarinic receptor antagonists?
atropine, tropicamide, ipratropium, triotropium, scopolamine, benztropine, trihexyphenidyl
atropine: characteristics and clinical uses
characteristics: tertiary amine (enters CNS)
clinical uses: antispasmodic, antisecretory, management of AChE inhibitors overdose, antidiarrheal, ophthalmology (long action)
pharmacologic effects of atropine
decreased secretions, mydriasis, cycloplegia, hyperthermia, tachycardia, sedation, urinary retention and constipation, excitation and hallucinations (mimics alzheimer’s)
