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14 Cards in this Set
- Front
- Back
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What are the classic muscarinic antagonists?
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The tertiary amines Atropine and Scopolamine.
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Atropine
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Cholinergic antagonist. Active in CNS. OD is typified by anticholinergic toxidrome mnemonic: "hot as a hare, blind as a bat, dry as a bone, red as a beet, and mad as a hatter". Biphasic HR dose response d/t pre- and post-synaptic mAChRs.
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Scopolamine
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Muscarinic antagonist. Used to treat motion sickness. SEs follow typical anticholinergic toxidrome.
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N-Methyl Atropine
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Muscarinic antagonist. Quaternary amine - poor CNS penetration. No clinical use.
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Ipratropium
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Muscarinic antagonist. Quaternary amine - poor CNS penetration. Used as an inhaled treatment for asthma and COPD.
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Tiotropium
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M2 Muscarinic Antagonist. Used to treat bronchospasm in COPD.
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What are the toxic effects of muscarinic antagonists?
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Therapeutic doses:
* Visual problems * Constipation and urinary retention * Glaucoma in predisposed individuals * Hallucinations and delirium * Decreased sweating and salivation * Erectile problems/impaired vaginal lubrication (Anticholinergic toxidromes at high doses/OD) |
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What effect can tri-cyclic antidepressants have on cholinergics?
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TCAs can serve as cholinergic antagonists when co-administered with cholinergic agonists.
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What's Physostigmine?
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A covalent, reversible AChE inhibitor (i.e. pharmacologic cholinergic agonist.)
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What are the three muscarinic AChRs learned about in class?
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* M1- in sympathetic ganglia (and adrenal medulla), activated by McN-A-343, blocked by pirenzepine
* M2- cardiac mAChR; can contribute to contraction of some smooth muscles; a presynaptic receptor on some nerve terminals * M3- mediates contraction of smooth muscle, relaxation of vasculature, and secretion from many glands |
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Cevimeline
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Selective M3 Agonist. Used in the treatment of Xerostomia and Sjogren's syndrome. SEs include excess secretions.
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Tiotropium
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[From the slides] Long-acting selective M3 antagonist, used to treat COPD. Poor absorption, used as an inhaler. Quaternary amine, few systemic SEs.
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McN–A–343
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Ganglionic mAChR agonist; results in a SANS activation. No cardiac or BV response.
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Pirenzepine
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Selective M1 AChR antagonist. Blocks histamine release in enterochromaffin-like cells in the stomach. Used for peptic ulcer disease in Europe.
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