Neuromuscular Blocking Drugs Mechanism
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Questions and Answers

What is the mechanism of action of succinylcholine?

  • Competitive inhibition of ACh at the nicotinic receptor
  • Increasing the release of ACh from the nerve terminal
  • Blockage of the voltage-gated sodium channels
  • Persistent depolarization of the muscle membrane (correct)

    • Which of the following is a characteristic of non-depolarizing NMBDs?

  • Fast onset and short duration of action
  • Can be reversed by anticholinesterases (correct)
  • Has a high volume of distribution
  • May cause muscle fasciculations and hyperkalemia

    • What is a common adverse effect of NMBDs?

  • Hypertension
  • Tachypnea
  • Bronchospasm (correct)
  • Diarrhea

    • How do NMBDs work?

    <p>By blocking the action of ACh at the neuromuscular junction</p> Signup and view all the answers

    What is a pharmacokinetic characteristic of NMBDs?

    <p>Highly protein-bound</p> Signup and view all the answers

    Which of the following is NOT a characteristic of depolarizing NMBDs?

    <p>Can be reversed by anticholinesterases</p> Signup and view all the answers

    What is the primary use of NMBDs in anesthesia?

    <p>To facilitate tracheal intubation and provide muscle relaxation</p> Signup and view all the answers

    Which of the following is a factor that can affect the dose-response curve of NMBDs?

    <p>All of the above</p> Signup and view all the answers

    What is a potential adverse effect of non-depolarizing NMBDs?

    <p>Histamine release leading to hypotension and bronchospasm</p> Signup and view all the answers

    What determines the duration of action of NMBDs?

    <p>Elimination half-life</p> Signup and view all the answers

    Study Notes

    Mechanism of Action

    • Neuromuscular blocking drugs (NMBDs) work by blocking the action of acetylcholine (ACh) at the neuromuscular junction
    • They compete with ACh for binding sites on the nicotinic receptor, preventing muscle contraction
    • Can be classified as depolarizing or non-depolarizing blockers

    Depolarizing NMBDs

    • Examples: Succinylcholine (SCh)
    • Mechanism: Causes persistent depolarization of the muscle membrane, leading to muscle paralysis
    • Characteristics:
      • Fast onset and short duration of action
      • Can cause muscle fasciculations, hyperkalemia, and cardiac arrhythmias
      • Not reversed by anticholinesterases

    Non-Depolarizing NMBDs

    • Examples: Atracurium, Vecuronium, Rocuronium, Cisatracurium
    • Mechanism: Competitive inhibition of ACh at the nicotinic receptor
    • Characteristics:
      • Slower onset and longer duration of action compared to depolarizing blockers
      • Can be reversed by anticholinesterases (e.g., neostigmine)
      • May cause histamine release, leading to hypotension and bronchospasm

    Pharmacokinetics and Pharmacodynamics

    • NMBDs are highly protein-bound and have a large volume of distribution
    • Elimination half-lives vary among agents, ranging from minutes (SCh) to hours (Atracurium)
    • Dose-response curves are steep, with significant interindividual variability
    • NMBDs can be affected by factors such as age, renal and hepatic function, and underlying medical conditions

    Clinical Uses and Adverse Effects

    • Used in anesthesia to facilitate tracheal intubation and provide muscle relaxation during surgery
    • Adverse effects:
      • Respiratory: respiratory depression, bronchospasm
      • Cardiovascular: hypotension, tachycardia
      • Neuromuscular: postoperative residual curarization, muscle weakness
      • Other: anaphylaxis, malignant hyperthermia

    Mechanism of Action

    • Neuromuscular blocking drugs (NMBDs) block the action of acetylcholine (ACh) at the neuromuscular junction by competing for binding sites on the nicotinic receptor.
    • This competition prevents muscle contraction, leading to muscle paralysis.

    Depolarizing NMBDs

    • Succinylcholine (SCh) is an example of a depolarizing NMBD.
    • Depolarizing NMBDs cause persistent depolarization of the muscle membrane, leading to muscle paralysis.
    • Characteristics of depolarizing NMBDs:
      • Fast onset and short duration of action
      • Can cause muscle fasciculations, hyperkalemia, and cardiac arrhythmias
      • Not reversed by anticholinesterases

    Non-Depolarizing NMBDs

    • Examples of non-depolarizing NMBDs: Atracurium, Vecuronium, Rocuronium, Cisatracurium
    • Non-depolarizing NMBDs work through competitive inhibition of ACh at the nicotinic receptor.
    • Characteristics of non-depolarizing NMBDs:
      • Slower onset and longer duration of action compared to depolarizing blockers
      • Can be reversed by anticholinesterases (e.g., neostigmine)
      • May cause histamine release, leading to hypotension and bronchospasm

    Pharmacokinetics and Pharmacodynamics

    • NMBDs are highly protein-bound and have a large volume of distribution.
    • Elimination half-lives of NMBDs vary among agents, ranging from minutes (SCh) to hours (Atracurium).
    • Dose-response curves are steep, with significant interindividual variability.
    • Factors affecting NMBDs: age, renal and hepatic function, and underlying medical conditions.

    Clinical Uses and Adverse Effects

    • Clinical uses of NMBDs: facilitating tracheal intubation and providing muscle relaxation during surgery.
    • Adverse effects of NMBDs:
      • Respiratory: respiratory depression, bronchospasm
      • Cardiovascular: hypotension, tachycardia
      • Neuromuscular: postoperative residual curarization, muscle weakness
      • Other: anaphylaxis, malignant hyperthermia

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    Description

    Learn about the mechanism of action of neuromuscular blocking drugs, including how they work and their classification into depolarizing and non-depolarizing blockers.

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