Adrenergic Agonists
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Questions and Answers

What type of receptors are stimulated by norepinephrine or epinephrine?

  • Adrenergic receptors (correct)
  • Cholinergic receptors
  • Dopaminergic receptors
  • GABA receptors

    • What are drugs that block activation of adrenergic receptors termed?

  • Sympatholytics (correct)
  • Sympathomimetics
  • Adrenergic agonists
  • Dopamine antagonists

    • Which of the following is NOT a direct-acting adrenergic agonist?

  • Indirect-acting agonist (correct)
  • Adrenaline
  • Noradrenaline
  • Dopamine

    • What is the role of dopamine in the context of adrenergic agonists?

    <p>A metabolic precursor of noradrenaline and adrenaline</p> Signup and view all the answers

    What is the term for drugs that activate adrenergic receptors?

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

    Which of the following is an example of an indirect-acting adrenergic agonist?

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

    What is the characteristic of catecholamines that allows them to directly activate α or β receptors?

    <p>High potency</p> Signup and view all the answers

    What enzyme is responsible for metabolizing catecholamines postsynaptically?

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

    What is the effect of oral administration of catecholamines?

    <p>They are inactivated and ineffective</p> Signup and view all the answers

    What is the structural feature of adrenergic agonists that affects their ability to differentiate between α and β receptors?

    <p>The number and location of OH substitutions on the benzene ring</p> Signup and view all the answers

    What is the location of the enzyme responsible for metabolizing catecholamines in the gut wall?

    <p>Gut wall</p> Signup and view all the answers

    What is the reason why norepinephrine is not useful in the treatment of bronchospasm or anaphylaxis?

    <p>It has a weak β2 activity</p> Signup and view all the answers

    What is the effect of norepinephrine on blood pressure?

    <p>It increases blood pressure</p> Signup and view all the answers

    What is the characteristic of catecholamines that limits their duration of action when given parenterally?

    <p>Rapid inactivation</p> Signup and view all the answers

    What is the result of the baroreceptor reflex stimulated by norepinephrine?

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

    What is the effect of atropine on the heart rate response to norepinephrine?

    <p>It blocks the bradycardia and reveals a tachycardia</p> Signup and view all the answers

    What is the primary therapeutic use of norepinephrine?

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

    What is the effect of norepinephrine on the contractility of the heart?

    <p>It increases the contractility</p> Signup and view all the answers

    What is the primary effect of clonidine on sympathetic vasomotor centers?

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

    What is the most common side effect of albuterol, metaproterenol, and terbutaline?

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

    What is the primary use of albuterol, metaproterenol, and terbutaline?

    <p>Management of acute asthma symptoms</p> Signup and view all the answers

    Why is abrupt discontinuation of clonidine avoided?

    <p>To prevent rebound hypertension</p> Signup and view all the answers

    What is the selectivity of albuterol compared to metaproterenol?

    <p>More selective for β2 receptors</p> Signup and view all the answers

    What is the off-label use of injectable terbutaline?

    <p>Suppression of premature labor</p> Signup and view all the answers

    What is tyramine's primary mechanism of action in the nerve terminal?

    <p>Displacing stored norepinephrine and releasing it into the synaptic space</p> Signup and view all the answers

    Why do small doses of catecholamines produce greatly magnified effects in an individual taking cocaine?

    <p>Cocaine potentiates the actions of epinephrine and norepinephrine by blocking their uptake</p> Signup and view all the answers

    What is the effect of MAOIs on the metabolism of tyramine?

    <p>MAOIs decrease the oxidation of tyramine in the gastrointestinal tract</p> Signup and view all the answers

    What is the mechanism of action of ephedrine and pseudoephedrine?

    <p>They stimulate both α and β receptors and enhance the release of stored norepinephrine</p> Signup and view all the answers

    What is the effect of cocaine on the duration of action of epinephrine and norepinephrine?

    <p>Cocaine increases the duration of action of epinephrine and norepinephrine</p> Signup and view all the answers

    What is the primary effect of tyramine on blood pressure?

    <p>Tyramine increases blood pressure by α1 agonist actions and β stimulatory effects</p> Signup and view all the answers

    What is the enzyme responsible for the conversion of tyrosine to dihydroxyphenylalanine in the adrenergic neuron?

    <p>Tyrosine hydroxylase</p> Signup and view all the answers

    What is the purpose of the amine transporter system in the adrenergic neuron?

    <p>To transport dopamine into synaptic vesicles</p> Signup and view all the answers

    What is the trigger for the release of norepinephrine from the synaptic vesicles?

    <p>An influx of calcium ions from the extracellular fluid</p> Signup and view all the answers

    What is the fate of norepinephrine released from the synaptic vesicles?

    <p>It binds to postsynaptic receptors on the effector organ or to presynaptic receptors on the nerve ending</p> Signup and view all the answers

    What is the effect of guanethidine on the release of norepinephrine?

    <p>It blocks the release of norepinephrine</p> Signup and view all the answers

    What is the rate-limiting step in the formation of norepinephrine?

    <p>The conversion of tyrosine to dihydroxyphenylalanine</p> Signup and view all the answers

    What is the effect of epinephrine on renal blood flow?

    <p>It decreases renal blood flow</p> Signup and view all the answers

    What type of receptors are responsible for epinephrine's effect on the liver and skeletal muscle?

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

    What is the mechanism of epinephrine's hyperglycemic effect?

    <p>Increased glycogenolysis in the liver and increased release of glucagon</p> Signup and view all the answers

    What is the effect of epinephrine on mast cells?

    <p>It inhibits the release of allergy mediators such as histamine</p> Signup and view all the answers

    What is the effect of epinephrine on the bronchial smooth muscle?

    <p>It causes powerful bronchodilation</p> Signup and view all the answers

    Which of the following receptors is activated by epinephrine to cause renin release?

    <p>β1 receptors</p> Signup and view all the answers

    What is the primary effect of oxymetazoline on blood vessels supplying the nasal mucosa and conjunctiva?

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

    What is the reason why prolonged use of dobutamine may lead to decreased effectiveness?

    <p>Tolerance may develop</p> Signup and view all the answers

    What is the mechanism by which clonidine decreases sympathetic outflow to the periphery?

    <p>It acts centrally on presynaptic α2 receptors to produce inhibition of sympathetic vasomotor centers.</p> Signup and view all the answers

    What is the primary effect of phenylephrine on blood pressure?

    <p>Increases both systolic and diastolic blood pressure</p> Signup and view all the answers

    What is the primary difference between albuterol and metaproterenol in their use as bronchodilators?

    <p>Albuterol is more selective for β2 receptors, while metaproterenol is less selective for β2 receptors.</p> Signup and view all the answers

    What is the potential adverse effect of oxymetazoline use for more than 3 days?

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

    What is the result of abruptly discontinuing clonidine therapy?

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

    What is the primary receptor type targeted by phenylephrine?

    <p>α1 receptors</p> Signup and view all the answers

    What is the off-label use of injectable terbutaline in the United States?

    <p>As a uterine relaxant to suppress premature labor</p> Signup and view all the answers

    What is the potential side effect of oxymetazoline administration via the intranasal route?

    <p>Local irritation and sneezing</p> Signup and view all the answers

    What is the most common side effect of clonidine?

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

    What is the reason why patients tend to develop tolerance to the side effect of tremor caused by albuterol, metaproterenol, and terbutaline?

    <p>Because the body adapts to the constant stimulation of β2 receptors</p> Signup and view all the answers

    What is the primary reason for avoiding concomitant use of MAOIs with direct-acting adrenergic agonists?

    <p>To reduce the risk of adverse cardiovascular effects</p> Signup and view all the answers

    What is the primary difference between salmeterol and formoterol in terms of their onset of action?

    <p>Salmeterol has a slower onset of action</p> Signup and view all the answers

    What is the recommended treatment approach for asthma when using LABAs?

    <p>Combination therapy with an inhaled corticosteroid</p> Signup and view all the answers

    What is the characteristic of LABAs that allows them to provide sustained bronchodilation over 12 hours?

    <p>Their long-acting duration of action</p> Signup and view all the answers

    What is the primary concern associated with the use of LABAs as monotherapy for asthma?

    <p>Increased risk of asthma-related deaths</p> Signup and view all the answers

    What is the difference in the duration of bronchodilation between albuterol and LABAs?

    <p>LABAs have a longer duration of action</p> Signup and view all the answers

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