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41 Cards in this Set
- Front
- Back
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What are cholinomimetic drugs?
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They mimic parasympathetic activity "rest/digest".
Muscarinic agonists |
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Direct acting muscarinic agonist agents
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Carbachol
Bethanechol Acetylcholine Methacholine Pilocarpine Cevimeline Muscarine |
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Direct acting muscarinic agonist agents MOA
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Bind to and activate muscarinic receptors
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REMEMBER
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Heart --> decrease HR
Blood vessels --> vasodilation (via NO) Ciliary muscle --> contraction/near vision Irish sphincter --> miosis GI tract --> increase activity Bladder --> micturation |
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What would be the problem with using ACh as a drug?
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Too nonspecific and very rapidly hydrolyzed by AChE and pseudo AChE
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What are the therapeutic uses of Bethanechol?
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Postoperative abdominal distension and urinary retention
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What are the therapeutic uses of Pilocarpine?
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Miotic
OAG NAG Sjogren's syndrome Radiation induced dry mouth |
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What effect does muscarnic receptor activation have in teh eye?
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Contract ciliary muscle
Contract iris sphincter--miosis |
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How is Pilocarpine used?
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For radiation of cancer in head or neck or for Sjogren's syndrome --> decreased salivary secretion --> Pilocarpine --> activate M receptor --> increased salivation
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What is Cevimeline used for?
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Newer drug for Sjogren's syndrome (longer lasting)
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What is Carbachol used for?
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It is the 2nd line drug after Pilocarpine in the treatment of glaucoma.
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What is Muscarine?
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It is NOT a drug and is present in Inocybe and Clitocybe mushrooms; mushroom poisoning (mycetism)
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What symptoms might you expect to see in a person who has mushroom poisoning from Inocybe mushrooms?
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Adverse effects of muscarinic agonists
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Direct acting muscarinic agonist
Adverse Effects? |
Salivation
Sweating Intestinal cramps/NVD Increased gastric acid secretion Hypotension Reflex tachycardia Difficulty breathing/asthma attack |
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How does muscarine and barorecptors work together?
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Muscarine --> M3 --> decreased BP --> baroreceptor --> CNS --> increased HR and force of contraction
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What are the adverse effects of direct acting muscarinic agonists on the eye?
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Contract cilicary muscle --> lens rounds out --> near vision (spasm of accomodation--blurry)
Contract iris sphincter --> miosis |
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Indirect acting cholinomimetics
Reversible AChE inhibitor agents? |
"Stigmine" and "riums"
Physostigmine Neostigmine Pyridostigmine Edrophonium Edrophonium + Atropine Ambenonium Demecarium |
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Indirect acting cholinomimetics
Reversible AChE inhibitor agents that work in CNS? |
Donepezil
Tacrine Rivastigmine Galantamine |
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Reversible AChE inhibitors MOA
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Slows down the hydrolysis of ACh by AChE.
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What happens to acetylcholine in the presence of neostigmine?
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Neo binds to enzyme and ACh can't hydrolyze --> prolonged activity of ACh at receptor
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Where is the site of action of physostigmine?
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All cholinergic synapses--not very specific.
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What are the therapeutic uses of physostigmine?
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Miotic
Treatment of glaucoma Reverses antimuscarinic effects from plants that contain muscarinic blockers and drugs that have antimuscarinic effects. Advantage: Lipid soluble |
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What are the therapeutic uses of neostigmine and pyridostigmine?
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Postoperative urinary retention and abdominal distention (Neo)
Myasthenia Gravis (both) |
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What other agent can be used to treat postoperative abdominal distention and urinary retention?
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Bethanechol
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How can we increase muscle strenth in patients with MG?
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Increase the concentration of ACh in the NMJ --> increased muscle strength
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What is the duration of action of Neostigmine?
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2 to 4 hours
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What is the duration of action of Pyridostigmine?
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3 to 6 hours
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What is Edrophonium?
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Analog of neostigmine
Less potent Shorter acting (3-4 minutes) IV only |
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What are the therapeutic uses of edrophonium?
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Diagnostic test for MG
Pt is weak --> give edrophonium --> improved muscle strength for 3-5 min. |
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What are the other therapeutic uses of edrophonium?
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Assesses the adequacy of treatment with neo
Differentiates between a myasthenic crisis and a cholinergic crisis |
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How can one tell if the Neostigmine dose is too high?
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Pt on neo --> weak --> give edrophonium --> decrease or no change in muscle strength --> Neo dose is too high
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How can one tell if the Neo dose is too low?
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Pt on neo --> weak --> give edrophonium --> increase in muscle strength --> neo dose is too low
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How can too much neo produce muscle weakness?
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There is no time for muscle cells to repolarize (Depolarization blockade)
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What centrally acting reversible AChE inhibitors treat Alzheimer's Disease (AD)?
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Donepezil
Tacrine Rivastigmine Galantamine |
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What is the difference in the drugs that treat AD?
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All drugs produce a similar improvement in cognitive function. The biggest difference is in the dosing and side effects.
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Tacrine for AD
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Many side effects (especially GI and hepatotoxic)
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Donepezil for AD
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Least GI side effects, 1 X d dosing
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Galantamine for AD
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Middle GI side effects, 1 x d dosing
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Rivastigmine
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Most GI side effects, 2 X d dosing
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What is the newest drug for AD?
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Memantine which is an NMDA antagonist
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What is carbamate cholinesterase inhibitors used for?
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Garden insecticides--low dermal absorption
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