Cholinesterase Inhibitors Mechanism of Action
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Questions and Answers

Which of the following is a characteristic of M2 receptors in the CNS?

  • Neutral
  • Excitatory
  • Inhibitory (correct)
  • Stimulatory

    • What is the effect of M3 receptors on the smooth muscles?

  • Hyperpolarization
  • Relaxation
  • Contraction (correct)
  • No effect

    • Which of the following is a cholinomimetic that acts directly on cholinergic receptors?

  • Cevemiline
  • Bethanechol (correct)
  • Neostigmine
  • Pilocarpine

    • What is the effect of M3 receptors on the eye?

    <p>Miosis (D)</p> Signup and view all the answers

    Which of the following is a classification of cholinomimetics?

    <p>Direct and Indirect (C)</p> Signup and view all the answers

    What is the effect of M2 receptors on the heart?

    <p>Decreased heart rate (D)</p> Signup and view all the answers

    What is the mechanism of action of cholinesterase inhibitors?

    <p>Inhibition of acetylcholinesterase (A)</p> Signup and view all the answers

    What is the effect of M3 receptors on exocrine glands?

    <p>Increased secretion (A)</p> Signup and view all the answers

    What is the primary therapeutic use of Pilocarpine?

    <p>Treatment of dry eye and mouth (B)</p> Signup and view all the answers

    Which of the following is a therapeutic use of Neostigmine?

    <p>Treatment of post-operative paralytic ileus and urinary retention (D)</p> Signup and view all the answers

    What is the primary mechanism of action of Cholinomimetics?

    <p>Stimulation of muscarinic receptors (D)</p> Signup and view all the answers

    What is the primary difference between 3ry Amines and 4ry Amines?

    <p>Lipophilicity (D)</p> Signup and view all the answers

    What is the antidote for competitive NMBs?

    <p>Neostigmine (D)</p> Signup and view all the answers

    What is the primary adverse effect of cholinomimetics on the CNS?

    <p>Irritability and convulsions (C)</p> Signup and view all the answers

    What is the characteristic of Neostigmine in terms of its absorption?

    <p>Poorly absorbed, does not cross BBB and conjunctiva (C)</p> Signup and view all the answers

    What is the primary therapeutic use of Physostigmine?

    <p>Treatment of atropine toxicity (C)</p> Signup and view all the answers

    What is the primary difference between Muscarinic and Nicotinic receptors?

    <p>Function (D)</p> Signup and view all the answers

    Which of the following Cholinesterase Inhibitors is used to antagonize central and peripheral effects of atropine?

    <p>Physostigmine (B)</p> Signup and view all the answers

    What is the effect of Cholinesterase Inhibitors on skeletal muscle power?

    <p>Increase skeletal muscle power (B)</p> Signup and view all the answers

    What is the characteristic of Irreversible Cholinesterase Inhibitors?

    <p>They are highly lipid soluble and absorbed from all sites of the body (B)</p> Signup and view all the answers

    What is the primary effect of Physostigmine on the eye?

    <p>Miotic effect (C)</p> Signup and view all the answers

    Which of the following Cholinesterase Inhibitors is an analogue of Neostigmine with a longer duration of action and fewer visceral side effects?

    <p>Pyridostigmine (A)</p> Signup and view all the answers

    Study Notes

    Choline Esterase Inhibitors

    • Reversible inhibitors: Edrophonium (ultra-short acting), Neostigmine (intermediate acting), and Pyridostigmine (long-acting)
    • Irreversible inhibitors: Organophosphates, which are highly lipid soluble and absorbed from all sites of the body, even skin

    Mechanism of Action

    • Cholinesterase inhibitors bind to the enzyme acetylcholinesterase, preventing the breakdown of acetylcholine
    • This leads to an increase in acetylcholine levels, enhancing neurotransmission at cholinergic synapses

    Muscarinic Effects

    • M2 receptors: inhibitory in CNS, slow heart rate, and decrease contractility
    • M3 receptors:
      • Smooth muscle contraction
      • Bronchospasm
      • GIT and urinary bladder contraction
      • Eye: miosis, accommodation, and increased aqueous drainage
      • Exocrine glands: increased secretion
      • Vascular endothelium: NO release, vasodilation, and decreased blood pressure

    Classification of Cholinomimetics

    • Directly acting: Choline esters, Natural alkaloids
    • Indirectly acting: Reversible and irreversible inhibitors

    Therapeutic Uses of Cholinomimetics

    • 3ry Amines:
      • Hair tonic: Pilocarpine
      • Alzheimer's disease: Donepezil and Rivastagmine
      • Atropine toxicity: Physostigmine
      • Dry eye and mouth: Pilocarpine and Cevemiline
      • Miotics in glaucoma: Pilocarpine and Physostigmine
    • 4ry Amines:
      • Post-operative: Neostigmine and Bethanechol
      • Megacolon/prokinetic: Bethanechol
      • Myasthenia gravis: Pyridostigmine
      • Antidote for competitive NMBs: Neostigmine
      • Diagnosis of Myasthenia gravis: Edrophonium (ultra-short acting)

    Adverse Effects and Contraindications

    • CNS: Irritability, convulsions
    • Eye: Miosis, lid twitches, brow ache, and frontal headache
    • Exocrine: Lacrimation, salivation, and increased HCl secretion
    • CVS: Bradycardia, hypotension, cardiac arrest, and infarction
    • Respiratory: Bronchospasm and increased secretion
    • GI: Urination, diarrhea, colic, nausea, and vomiting
    • Muscular: Fasciculations and paralysis in toxic doses

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    Description

    Learn about the different types of cholinesterase inhibitors, including reversible and irreversible inhibitors, and their mechanisms of action.

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