Cholinergic Agonists Overview
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Questions and Answers

Which of the following is a direct-acting cholinomimetic?

  • Physostigmine
  • Edrophonium
  • Bethanechol (correct)
  • Pyridostigmine

    • Pilocarpine is classified as a choline ester.

    False

    What is the main clinical application of Bethanechol?

    Treatment of paralytic ileus

    _________ is a synthetic choline ester that acts on the GIT and urinary bladder.

    <p>Bethanechol</p> Signup and view all the answers

    Match the following cholinergic drugs to their classifications:

    <p>Bethanechol = Choline ester Pilocarpine = Alkaloid Methacholine = Diagnostic tool Physostigmine = Reversible inhibitor</p> Signup and view all the answers

    Which of the following cholinergic drugs cannot cross the blood-brain barrier (BBB)?

    <p>Bethanechol</p> Signup and view all the answers

    Indirect-acting cholinergic agonists enhance the effect of acetylcholine in the body.

    <p>True</p> Signup and view all the answers

    What is the significance of methacholine in clinical practice?

    <p>It is used as a diagnostic tool.</p> Signup and view all the answers

    What medication is used to treat non-obstructive urinary retention?

    <p>Bethanechol</p> Signup and view all the answers

    Pilocarpine can cross the blood-brain barrier.

    <p>True</p> Signup and view all the answers

    What is the primary feature of Sjögren's syndrome?

    <p>Dry eyes and dry mouth</p> Signup and view all the answers

    Bethanechol stimulates __________ receptors to promote the tone of the detrusor urinae muscle.

    <p>muscarinic acetylcholine</p> Signup and view all the answers

    Match the following clinical applications with the corresponding medication:

    <p>Bethanechol = Paralytic ileus Pilocarpine = Glaucoma</p> Signup and view all the answers

    Which medication is primarily used to treat glaucoma?

    <p>Pilocarpine</p> Signup and view all the answers

    Sjögren's syndrome primarily affects the liver.

    <p>False</p> Signup and view all the answers

    The main action of pilocarpine in treating xerostomia is to stimulate __________ secretions.

    <p>salivary</p> Signup and view all the answers

    What is the primary mechanism of action (MOA) of Bethanechol in treating non-obstructive urinary retention?

    <p>Stimulates muscarinic acetylcholine receptors</p> Signup and view all the answers

    Bethanechol can cross the blood-brain barrier (BBB).

    <p>False</p> Signup and view all the answers

    What condition is characterized by the obstruction of the intestine due to paralysis of intestinal muscle?

    <p>Paralytic ileus</p> Signup and view all the answers

    Bethanechol has a __________ duration of action compared to acetylcholine (Ach).

    <p>longer</p> Signup and view all the answers

    Match the conditions with their relevant causes:

    <p>Abdominal surgery = Causes paralytic ileus Certain drugs = Causes paralytic ileus Spinal injuries = Causes paralytic ileus Inflammation within abdomen = Causes paralytic ileus Disease of intestinal muscle = Causes paralytic ileus</p> Signup and view all the answers

    Which of the following clinical applications of Bethanechol is correct?

    <p>Treatment of paralytic ileus</p> Signup and view all the answers

    Bethanechol has a selective action on the urinary bladder and gastrointestinal tract.

    <p>True</p> Signup and view all the answers

    The activation of muscarinic acetylcholine receptors (mAChR) by Bethanechol __________ gastric motility.

    <p>stimulates</p> Signup and view all the answers

    What receptor does pilocarpine primarily act on?

    <p>M3</p> Signup and view all the answers

    Dry mouth can be treated with cevimeline in patients with Sjögren's syndrome.

    <p>True</p> Signup and view all the answers

    What is the primary clinical application of carbachol?

    <p>Glaucoma</p> Signup and view all the answers

    Pilocarpine facilitates outflow of aqueous humor through the canal of __________.

    <p>Schlemm</p> Signup and view all the answers

    Match the following drugs with their clinical uses:

    <p>Pilocarpine = Dry mouth Cevimeline = Glaucoma Carbachol = Miotic agent Bethanechol = Urinary retention</p> Signup and view all the answers

    Which of the following adverse effects is NOT associated with muscarinic agonists?

    <p>Hypertension</p> Signup and view all the answers

    Carbachol is not metabolized by cholinesterase.

    <p>True</p> Signup and view all the answers

    Name a soluble drug that has CNS effects among anticholinesterases.

    <p>Donepezil</p> Signup and view all the answers

    Overdosage of muscarinic agonists can lead to __________.

    <p>Miosis</p> Signup and view all the answers

    What is the mechanism of action of pilocarpine in treating glaucoma?

    <p>Contraction of ciliary muscle</p> Signup and view all the answers

    What is a clinical use of Physostigmine?

    <p>Glaucoma</p> Signup and view all the answers

    Echothiophate is an irreversible anticholinesterase used for the treatment of glaucoma.

    <p>True</p> Signup and view all the answers

    Name one symptom of organophosphate toxicity.

    <p>Severe bradycardia</p> Signup and view all the answers

    Organophosphate agents are categorized as _____ soluble, with the exception of echothiophate.

    <p>highly lipid</p> Signup and view all the answers

    Match the drug with its clinical use:

    <p>Edrophonium = Diagnosis of Myasthenia gravis Neostigmine = Urinary retention Atropine = Block muscarinic actions Pralidoxime = Reactivation of cholinesterase</p> Signup and view all the answers

    What class of conditions does Myasthenia gravis predominantly relate to?

    <p>Neuromuscular disorders</p> Signup and view all the answers

    Pralidoxime can reactivate cholinesterase if given after aging occurs.

    <p>False</p> Signup and view all the answers

    What is one effect of organophosphate poisoning on skeletal muscles?

    <p>Muscle weakness and paralysis</p> Signup and view all the answers

    Symptoms of sarin exposure can appear within _____ seconds after exposure to vapor form.

    <p>seconds</p> Signup and view all the answers

    Which of the following is NOT a symptom of organophosphate toxicity?

    <p>Hypertension</p> Signup and view all the answers

    Study Notes

    Cholinergic Agonists (Parasympathomimetic Agents)

    • Cholinergic agonists mimic the effects of acetylcholine, a neurotransmitter in the parasympathetic nervous system.
    • Learning outcomes include understanding the major cholinergic drug groups and their mechanisms of action, how direct-acting and indirect-acting agonists affect the parasympathetic nervous system, and the therapeutic applications and risks associated with cholinergic drugs.
    • Key groups of cholinoceptor stimulants include choline esters (e.g., pilocarpine, methacholine) and alkaloids (e.g., physostigmine).
    • Direct-acting drugs bind directly to muscarinic and nicotinic receptors.
    • Indirect-acting drugs inhibit acetylcholinesterase, increasing the amount of acetylcholine at the synapse.
    • Clinically used cholinergic agonists include choline esters (bethanecol, carbachol, cevimeline, methacholine - diagnostic tool) and alkaloids (pilocarpine). Acetylcholine itself, however, is generally not used clinically due to its widespread effects.
    • Bethanecol: a synthetic ester, selective for the GI tract and urinary bladder, with a longer duration of action than acetylcholine, and doesn't cross the blood-brain barrier. Used to treat paralytic ileus (post-surgery) and non-obstructive urinary retention.
    • Pilocarpine: a plant alkaloid, targets exocrine glands (primarily M3) and the eye, and crosses the blood-brain barrier. Used for xerostomia (dry mouth), related to head and neck radiation or Sjögren's syndrome, and glaucoma (eye drops).
    • Cevimeline: a more selective muscarinic agonist, primarily acting on M3 receptors in exocrine glands. Used to treat symptoms of dry mouth in Sjögren's syndrome.
    • Carbachol is a direct acting cholinomimetic drug used as a miotic agent (pupil constriction) and in treating glaucoma.
    • Adverse effects of muscarinic agonists can include overdosage, miosis, bradycardia, arrhythmias, hypotension and bronchoconstriction.
    • Anticholinesterases: (indirect-acting) increase acetylcholine levels by inhibiting the enzyme acetylcholinesterase used in treatment for myasthenia gravis. There are reversible and irreversible types with different durations of action.
    • Irreversible anticholinesterases, like organophosphates, include nerve agents (e.g. Sarin, VX) and insecticides, and can result in more serious effects, like respiratory and cardiac failure. Their effects are often long-lasting due to their irreversible nature.
    • Treatment for organophosphate toxicity involves atropine (muscarinic antagonist) and cholinesterase reactivators to regenerate the inhibited enzyme; especially if given before the aging process of the organophosphate occurs.

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    Lecture Note_Cholinergic Agonists PDF

    Description

    Explore the key concepts of cholinergic agonists, their mechanisms of action, and therapeutic applications. This quiz covers direct-acting and indirect-acting agents, along with major drug groups like choline esters and alkaloids. Assess your understanding of how these agents affect the parasympathetic nervous system.

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