Adrenergic agonist
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Questions and Answers

What is the effect of adrenaline on blood vessels at high doses?

  • No effect on blood vessels
  • Dilation of blood vessels in the liver and skin
  • Dilation of arterioles in skin, mm, and viscera
  • Constriction of arterioles in skin, mm, and viscera (correct)

    • What is the primary mechanism of inactivation of catecholamines?

  • Inactivation by COMT in the neuron and by MAO post-synoptically
  • Inactivation by MAO in the neuron and by COMT post-synoptically
  • Inactivation by COMT and MAO in the bloodstream
  • Inactivation by COMT post-synoptically and by MAO in the neuron (correct)

    • Which of the following is NOT a characteristic of catecholamines?

  • They are lipophilic
  • They contain catechol in their structure
  • They can penetrate the blood-brain barrier (correct)
  • They are rapidly inactivated by COMT and MAO

    • What is the effect of adrenaline on the cardiovascular system at low doses?

    <p>+ve inotropic and +ve chronotropic effect</p> Signup and view all the answers

    What is the effect of the fight or flight response on respiration?

    <p>Increase in depth and rate of respiration</p> Signup and view all the answers

    Which of the following is a characteristic of non-catecholamines?

    <p>They are lipophilic and can penetrate the blood-brain barrier</p> Signup and view all the answers

    What is the effect of adrenaline on blood pressure?

    <p>Increase in systolic blood pressure and decrease in diastolic blood pressure</p> Signup and view all the answers

    Which of the following is an example of a direct non-selective agonist?

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

    What is the effect of the fight or flight response on muscle glycogen?

    <p>Increase in muscle glycogen</p> Signup and view all the answers

    What is the effect of adrenaline on renal blood flow?

    <p>Increase in renal blood flow</p> Signup and view all the answers

    What is the effect of epinephrine on glycogenolysis?

    <p>Increase hepatic glycogenolysis</p> Signup and view all the answers

    What is the main indication for the use of noradrenaline?

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

    What is the effect of isoprenaline on peripheral resistance?

    <p>Decrease peripheral resistance</p> Signup and view all the answers

    What is the action of dopamine on D1 receptors?

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

    What is the side effect of epinephrine on the central nervous system?

    <p>Headache, anxiety, and tremor</p> Signup and view all the answers

    What is the effect of epinephrine on insulin release?

    <p>Decrease insulin release</p> Signup and view all the answers

    What is the effect of noradrenaline on heart rate?

    <p>Decrease heart rate</p> Signup and view all the answers

    What is the effect of isoprenaline on bronchial smooth muscle?

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

    What is the side effect of noradrenaline on the cardiovascular system?

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

    What is the action of dopamine on D2 receptors?

    <p>Similar to alpha-2 receptor</p> Signup and view all the answers

    What is the main mechanism of indirect acting agonists?

    <p>They potentiate the endogenous norepinephrine and epinephrine</p> Signup and view all the answers

    Which of the following adrenergic agonists is used to control withdrawal symptoms from opiates?

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

    What is the main side effect of clonidine?

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

    Which of the following adrenergic agonists has a slow onset bronchodilator effect?

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

    What is the mechanism of desensitization of adrenergic receptors?

    <p>Sequestration of the receptors</p> Signup and view all the answers

    Which of the following adrenergic agonists is used topically as a nasal or oral decongestant?

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

    What is the main use of phenylephrine in ophthalmology?

    <p>To produce mydriasis</p> Signup and view all the answers

    Which of the following adrenergic agonists has a short half-life?

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

    Which of the following is a side effect of adrenergic agonists?

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

    Which of the following classes of adrenergic agents has utility in the management of hypertension?

    <p>α2 Agonist</p> Signup and view all the answers

    Which of the following is NOT an indication for fenoldopam?

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

    What is the mechanism of action of alpha-1 receptors?

    <p>G-protein coupled - PLC - IP3+DAG - Ca++</p> Signup and view all the answers

    Which of the following beta-agonists is used in premature labor?

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

    What is the primary indication for dobutamine?

    <p>Acute heart failure</p> Signup and view all the answers

    What is the primary side effect of oxymetazoline?

    <p>Rebound congestion</p> Signup and view all the answers

    What is the mechanism of action of beta-2 agonists?

    <p>G-protein coupled - AC - cAMP</p> Signup and view all the answers

    What is the primary indication for fenoldopam?

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

    What is the primary side effect of SABA?

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

    Which of the following is a long-acting beta-2 agonist?

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

    What is the primary indication for oxymetazoline?

    <p>Nasal congestion</p> Signup and view all the answers

    Study Notes

    Adrenergic Agonists

    • Adrenergic agonists are substances that stimulate the adrenergic receptors in the body, which can lead to a variety of physiological responses.

    Synthesis and Release

    • Catecholamines are synthesized in the adrenal medulla and nerve endings.
    • They are inactivated by COMT post-synaptically and by MAO in the neuron.
    • They have a short duration of action.

    Actions and Receptors

    • Adrenergic receptors are categorized into α, β, and dopamine receptors.
    • α receptors are further divided into α1 and α2 receptors.
    • β receptors are divided into β1, β2, and β3 receptors.
    • Dopamine receptors are divided into D1 and D2 receptors.

    Direct Acting Agonists (Non-Selective)

    • Adrenaline (Epinephrine)

      • Acts on α and β receptors
      • At low doses, it has β effects (vasodilation)
      • At high doses, it has α effects (vasoconstriction)
      • Indications: anaphylaxis, bronchospasm, cardiac arrest, dental use, epistaxis, and intraocular surgery
      • Side effects: CNS (headache, anxiety, tremor), CVS (hypertension, dysrhythmia, angina pectoris), respiratory (pulmonary edema), metabolic (hyperglycemia)

    • Noradrenaline (Norepinephrine)

      • Acts on α receptors
      • Increases peripheral resistance and systolic blood pressure
      • Indications: shock
      • Contraindications: peripheral vascular diseases, hypertension, asthma
      • Side effects: same as epinephrine, plus sloughing and necrosis at the injection site

    • Isoprenaline

      • Synthetic catecholamine
      • Non-selective β-1 and β-2 agonist
      • Acts on the heart (increases contractility and rate) and respiratory system (bronchodilation)
      • Side effects: same as epinephrine

    • Dopamine

      • Acts on D1 and D2 dopamine receptors
      • Indications: cardiogenic and septic shock, hypotension, oliguria, bradycardia, and severe heart failure
      • Side effects: hypertension, dysrhythmias are short-lived

    Direct Acting Agonists (Selective)

    • Dobutamine

      • Synthetic catecholamine
      • β1 agonist
      • Increases cardiac contractility and heart rate
      • Indications: acute heart failure, cardiac surgery
      • Side effects: increases oxygen demand of the myocardium

    • SABA (Short-Acting Beta-2 Agonist)

      • Albuterol, metaproterenol, and terbutaline
      • β2 agonist
      • Bronchodilator (inhaler)
      • Terbutaline injection relaxes the uterus, used in premature labor
      • Side effects: tremor, restlessness, anxiety, tachycardia (if given orally)

    • LABA (Long-Acting Beta-2 Agonist)

      • Salmeterol, indacaterol, and formoterol
      • β2 agonist
      • Long-acting (12 hours)
      • Indications: asthma and COPD
      • Used in combination with other asthma medications as inhaled corticosteroids

    • Oxymetazoline

      • α1 and α2 agonist
      • Ophthalmic and nasal decongestant
      • Side effects: irritation, sneezing (nasal administration), headaches, and sleep disturbances

    • Phenylephrine

      • Selective α1 agonist
      • Vasoconstrictor (increases systolic and diastolic blood pressure)
      • Uses: hypotension in patients with rapid heart rate, paroxysmal supraventricular tachycardia, topical decongestant, and ophthalmic solution for mydriasis
      • Side effects: large doses cause hypertensive headache and cardiac irregularities

    • Clonidine

      • Selective α2 agonist
      • Used to treat hypertension by inhibiting sympathetic vasomotor center, decreasing sympathetic outflow
      • Used to control withdrawal symptoms from opiates, benzodiazepines, and tobacco
      • Side effects: lethargy, sedation, xerostomia

    Indirect Acting Agonists

    • They potentiate the endogenous nor-epinephrine and epinephrine by increasing release, inhibiting re-uptake, or inhibiting degradation.
    • Examples: amphetamine, tyramine, cocaine, and MAO/COMT inhibitors.

    Mixed Agonists

    • They induce release of nor-epinephrine and activate adrenergic receptors.
    • Examples: ephedrine and pseudoephedrine
    • They have α1 and β effects, and penetrate the CNS
    • Uses: ephedrine is used in hypotension, and pseudoephedrine is used in nasal and sinus congestion.

    Adrenergic Agonists Adverse Effects

    • Arrhythmias
    • Hyperactivity
    • Insomnia
    • Tremors
    • Tachycardia
    • Headache
    • Nausea

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    Description

    This quiz covers the sympathetic nervous system, including the fight or flight response, synthesis and release, actions and receptors, and effects on the body.

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