Sympathomimetics Classification and Actions
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Questions and Answers

Which type of adrenoceptors are primarily responsible for the fight-or-flight response in the sympathetic nervous system?

  • Beta-2
  • Alpha-1 (correct)
  • Beta-1
  • Alpha-2

    • What is the main endogenous ligand for the adrenoceptors in the human body?

  • Dopamine
  • Acetylcholine
  • Noradrenaline (correct)
  • Adrenaline

    • Which class of drugs directly activate adrenoceptors, leading to physiological responses similar to those of the sympathetic nervous system?

  • Sympathomimetics (correct)
  • Parasympathomimetics
  • Cholinesterase Inhibitors
  • Anticholinergics

    • Which neurotransmitter is primarily associated with dopaminergic receptors in the brain and peripheral nervous system?

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

    What is the primary mechanism of action for sympathomimetic drugs acting indirectly?

    <p>Preventing reuptake of neurotransmitters</p> Signup and view all the answers

    Which of the following drugs is classified as a non-selective α1, α2, β1, and β2 agonist?

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

    Which of the following is a potential side effect of β2-selective sympathomimetic drugs like salbutamol?

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

    Which of the following drugs is classified as a selective α2 agonist?

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

    Which of the following neurotransmitters is classified as a D1, D2, and β1 agonist?

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

    Which of the following drugs is classified as a selective β1 agonist?

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

    Which of the following is a potential side effect of α1-selective sympathomimetic drugs like phenylephrine?

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

    Which adrenergic receptor is adrenaline (epinephrine) NOT an agonist on?

    <p>D2</p> Signup and view all the answers

    What is a potential severe adverse effect of adrenaline (epinephrine) administration?

    <p>Cerebral hemorrhage</p> Signup and view all the answers

    Which medication is used for the treatment of anaphylactic shock through local vasoconstriction?

    <p>Adrenaline (epinephrine)</p> Signup and view all the answers

    Which neurotransmitter acts as a precursor for adrenaline and noradrenaline?

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

    What is a potential adverse effect associated with prolonged infusion of dopamine?

    <p>Gangrene of fingers/toes</p> Signup and view all the answers

    Which adrenergic receptor is not directly activated by Noradrenaline (Norepinephrine)?

    <p>β2</p> Signup and view all the answers

    In addition to its cardiovascular effects, what other effect is produced by Noradrenaline (Norepinephrine)?

    <p>Mucosal decongestion</p> Signup and view all the answers

    What is the primary effect of Dobutamine on the cardiovascular system?

    <ul> <li>Inotropy, + Dromotropy, + Chronotropy, + Bathmotropy</li> </ul> Signup and view all the answers

    Which of the following effects is not associated with Salbutamol?

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

    What type of drug inhibits the reuptake of norepinephrine and dopamine?

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

    Study Notes

    Introduction to Sympathetic Nervous System (SNS)

    • The sympathetic nervous system (SNS) is a part of the autonomic nervous system (ANS)
    • The SNS is responsible for the "fight or flight" response
    • The SNS is controlled by adrenergic receptors (adrenoceptors)

    Adrenergic Receptors (Adrenoceptors)

    • Adrenoceptors are G-protein coupled receptors (GPCR)
    • There are two main types of adrenoceptors: alpha (α) and beta (β)
    • Alpha receptors are further divided into α1 and α2, while beta receptors are divided into β1, β2, and β3
    • Dopamine receptors are also involved in the SNS and are divided into D1 and D2

    Sympathomimetics: Direct Acting

    • Sympathomimetics are drugs that mimic the effects of endogenous ligands on the SNS
    • Direct acting sympathomimetics are classified into non-selective, selective, and mixed acting
    • Non-selective sympathomimetics include adrenaline (α1, α2, β1, β2), noradrenaline (α1, α2, β1), and dopamine (D1, D2, β1)
    • Selective sympathomimetics include phenylephrine (α1), clonidine (α2), dobutamine (β1), and salbutamol (β2)

    Sympathomimetics: Indirect Acting

    • Indirect acting sympathomimetics include releasing agents, catecholamine reuptake inhibitors, and MAO/COMT inhibitors
    • Releasing agents, such as amphetamine, stimulate the release of catecholamines from storage vesicles
    • Catecholamine reuptake inhibitors, such as amitriptyline, block the reuptake of noradrenaline from the synapse
    • MAO/COMT inhibitors, such as phenelzine and selegiline, inhibit the metabolism of catecholamines

    Sympathomimetics: Mixed Acting

    • Mixed acting sympathomimetics, such as ephedrine, indirectly release noradrenaline and directly activate adrenoceptors (α1, α2, β1, β2)
    • Ephedrine is absorbed well orally and has a long duration of action
    • Ephedrine is excreted unchanged in the urine

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    Description

    Learn about the classifications and actions of sympathomimetic drugs that mimic the effects of endogenous ligands on the sympathetic nervous system. Explore the distinctions between non-selective and selective direct-acting sympathomimetics.

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