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24 Cards in this Set
- Front
- Back
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Name some direct-acting cholinergic agonists |
Bethanechol, carbechol, pilocarpine |
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Name some indirect-acting cholinergic agonists (reversible acetylcholinesterase inhibitors) and classify them according to the duration of action.
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Short-acting: Edrophonium Medium-acting: Neostigmine, physostigmine, pyridostigmine Long-acting: Donepezil, rivastigmine, galantamine |
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Name some irreversible acetylcholinesterase inhibitors
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Echothiophate, hexaethyl tetraphosphate, malathion, parathion |
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Name the acetylcholinesterase reactivator |
Pralidoxime |
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Name the two enzymes which can break down acetylcholine. |
Acetylcholinesterase and butyrylcholinesterase (= pseudocholinesterase) |
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Name some drugs which are broken down by pseudocholinesterase |
Succinylcholine, procaine |
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Where is acetylcholinesterase found? |
In the synaptic cleft |
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Where is pseudocholinesterase found? |
Plasma, skin, GI tract, liver, brain |
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What are the physiological effects of muscarinic M1 acetylcholine receptors? |
Increased gastric acid secretion |
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What are the physiological effects of muscarinic M2 acetylcholine receptors? |
Negative heart effects |
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What are the physiological effects of muscarinic M3 acetylcholine receptors? |
- Bronchoconstriction - Increased gland secretion - Increased gastric motility - Miosis - Ciliary muscle contraction |
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What are the indiciations of direct-acting cholinergic agonists? |
- Non-obstructive ileus - Urinary retention - Glaucoma - Sjögren syndrome |
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Describe the pharmacokinetics of betanechol. |
Bethanechol is a choline ester with a quaternary ammonium group. This makes it poorly lipid-soluble and therefore impossible for bethanechol to cross the blood-brain barrier. |
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Describe the pharmacokinetics of pilocarpine
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Pilocarpine is a tertiary amine that is well absorbed from the GI tract and readily enters the CNS. |
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What are the indications for indirect-acting cholinergic agonists? |
- Myasthenia gravis
- Glaucoma - Postoperative ileus - Urinary retention - Alzheimer disease - Atropine overdose |
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What is the mechanism of action of indirect-acting cholinergic agonists?
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They inhibit acetylcholinesterase, thereby decreasing the breakdown of endogenous acetylcholine in the synaptic cleft. They also inhbit pseudocholinesterase. |
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Describe the pharmacokinetics of indirect-acting cholinergic agonists.
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Edrophonium, neostigmine and pyridostigmine are quaternary amines and are therefore not orally absorbed and don't cross the BBB. Physostigmine, donepezil, rivastigmine and galantamine are orally absorbed and cross the BBB. |
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What are the most common uses of irreversible acetylcholinesterase inhibitors? |
They're used as insecticides and chemical warfare wepons. |
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What is the indication for pralidoxime?
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Organophosphate poisoning |
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What are organophosphates? |
All irreversible acetylcholinesterase inhibitors are organophosphates |
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Why do irreversible acetylcholinesterase inhibitors have such long duration of action? |
Because the cells must synthesize new molecules of acetylcholinesterase to overcome their effect. |
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What are the symptoms of organophosphate poisoning and cholinergic crisis? |
Parasympathetic overactivation, paralysis, convuslions and tremor. |
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What is the treatment of organophosphate poisoning?
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Pralidoxime and IV atropine |
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What is the treatment of cholinergic crisis? |
IV atropine |
