cholinomimetics Flashcards
name two direct agonists that are receptor nonspecific
- ACh
- carbachol
name three direct agonists that are muscarinics
- methacholine
- bethanechol
- pilocarpine
name three direct agonists that are nicotinic
- nicotine
- varenicline
name a short acting cholinesterase inhibitor (cholinomimetic)
edrophonium
name two intermediate acting cholinesterase inhibitors (carbamates)
- neostigmine
- physostigmine
name five long acting cholinesterase inhibitors (organophosphates)
- echothiophate
- parathion
- malathion
- sarin
- soman
name a presynaptic indirect cholinomimetic
metoclopramide
what is the one exception to the rule that sympathetics are stimulated by NE?
sympathetic sweat glands are stimulated by ACh
what clears ACh from blood quickly?
plasma pseudocholinesterase
where are muscarinic (M) receptors found?
1) effector tissues innervated by PS fibers
2) select post ganglionic sympathetic targets (sweat glands)
3) endothelium
what are the expected physiological signs of muscarinic receptor agonism?
1) hypotension
2) paradoxical bradycardia (when there should be tachycardia)
what does DUMBBELSS stand for?
clinical signs of muscarinic activation Diarrhea Urination Miosis (contraction of iris) Bronchorrhea Bradycardia Emesis (increased stomach and GI tone) Lacrimation (tearing) Salivation Sweating
what are the two nicotinic receptors and where are they found?
1) Nn found in all autonomic ganglia and in CNS
2) Nm found at NMJ on skeletal muscle
nicotinic receptors are what kind of channel?
ligand gated Na/K channels, depolarization triggers action potential
what is the main result of nicotine toxicity?
1) PSANS and SANS stimulation
2) paradoxical flaccid paralysis due to ACh inhabiting receptors for prolonged period, cannot be practically reversed, must wait for agonist to clear on its own
how is methacholine used clinically?
1) asthma airway challenge
how is bethanechol used? what replaced it?
- was used to relieve GI dysmotility
- replaced by metoclopramide
how is pilocarpine used clinically?
topically in the eye to relieve glaucoma
what is the only direct acting nicotinic agonist aside from nicotine and what is it used for?
varenicline, smoking cessation
how does varenicline work?
- prevents dopamine surges (no chemical reward) and also prevents low dopamine and cravings
- it stimulates nicotinic receptors less than nicotine does
side effects of varenicline
- suicidal thoughts
- neuropsychiatric symptoms
how is varenicline secreted?
urine
what do all ChE inhibitors block?
1) plasma ChE
2) AChE
3) RBC AChE
plasma ChE is inhibited first which protects AChE at first
What are AChE inhibitor side effects?
DUMBBELSS, same as muscarinic agonists
