Adrenergic Antagonists
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Adrenergic Antagonists

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Questions and Answers

Which adrenergic antagonist is primarily used for the treatment of pheochromocytomas?

  • Carvedilol
  • Yohimbine
  • Labetalol
  • Phentolamine (correct)

    • Which adrenergic antagonist mainly affects beta receptors but has some effect on alpha receptors?

  • Tolazoline
  • Labetalol (correct)
  • Phenoxybenzamine
  • Yohimbine

    • Which of the following statements about phenoxybenzamine is true?

  • It acts as a non-selective alpha antagonist. (correct)
  • It has higher affinity for alpha 1 than alpha 2 receptors.
  • It does not affect beta receptors.
  • It exclusively targets beta receptors.

    • Which adrenergic antagonist primarily affects the alpha 2 receptor?

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

    Yohimbine is predominantly used to affect which type of receptor?

    <p>Alpha 2</p> Signup and view all the answers

    What is a key clinical use of beta antagonists?

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

    Which adrenergic antagonist can cause sympathetic neurons to release high amounts of catecholamines?

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

    What is the primary effect of mixed antagonists like carvedilol?

    <p>Equal affinity for both alpha and beta receptors</p> Signup and view all the answers

    What is the primary effect of α2-selective adrenergic receptor antagonists?

    <p>Increase sympathetic outflow</p> Signup and view all the answers

    Which of the following effects is associated with the activation of α1 and β1 adrenergic receptors in the heart?

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

    In patients with coronary artery disease, the expected increase in myocardial O2 demand due to catecholamines can lead to which condition?

    <p>Myocardial ischemia</p> Signup and view all the answers

    What is a common misconception about the antihypertensive effects of beta-adrenergic antagonists?

    <p>They generally decrease blood pressure</p> Signup and view all the answers

    What is one of the pharmacological effects of the β adrenergic antagonists on myocardial oxygen consumption?

    <p>Decrease myocardial oxygen consumption</p> Signup and view all the answers

    What effect does propranolol have during dynamic exercise?

    <p>It blocks β2 receptors leading to bronchoconstriction.</p> Signup and view all the answers

    In which patient population should propranolol be used with caution?

    <p>Patients with bronchospastic diseases such as COPD.</p> Signup and view all the answers

    What is the primary reason for the increase in heart rate during exercise when using beta blockers?

    <p>Compensatory mechanisms due to decreased stroke volume.</p> Signup and view all the answers

    What metabolic effect do catecholamines have that is modified by propranolol?

    <p>They promote glycogenolysis and glucose mobilization.</p> Signup and view all the answers

    What happens to cardiac output during exercise when a patient is on beta blockers?

    <p>It is less affected because of increased stroke volume.</p> Signup and view all the answers

    What is a potential risk of using beta blockers in patients with COPD?

    <p>Life-threatening bronchoconstriction.</p> Signup and view all the answers

    Which of the following mechanisms is NOT a reason for increased coronary artery blood flow during exercise?

    <p>Decreased stroke volume.</p> Signup and view all the answers

    How does propranolol affect the response to hypoglycemia?

    <p>Inhibits glucose mobilization from the liver.</p> Signup and view all the answers

    What is the primary cardiovascular effect of propranolol during exercise?

    <p>To reduce myocardial oxygen demand.</p> Signup and view all the answers

    What is the relationship between β2 receptor blockade and pulmonary function in normal individuals?

    <p>It has little effect on pulmonary function.</p> Signup and view all the answers

    What type of antagonist is phenoxybenzamine?

    <p>Irreversible alpha-adrenergic antagonist</p> Signup and view all the answers

    Which adrenergic receptor type does Metoprolol primarily target?

    <p>Beta 1 receptors</p> Signup and view all the answers

    What is an important characteristic of adrenergic receptor antagonists?

    <p>Most are competitive antagonists</p> Signup and view all the answers

    How does Propranolol differ from Metoprolol regarding receptor affinity?

    <p>Propranolol has equal affinities for beta 1 and beta 2 receptors</p> Signup and view all the answers

    What is the role of adrenergic receptor antagonists in clinical practice?

    <p>To manage various cardiovascular conditions</p> Signup and view all the answers

    Butoxamine is recognized for having greater affinity for which receptor type?

    <p>Beta 2 receptors</p> Signup and view all the answers

    What distinguishes a selective antagonist like Metoprolol from non-selective types?

    <p>It specifically targets only beta 1 receptors</p> Signup and view all the answers

    What type of receptor interaction do most adrenergic antagonists exhibit?

    <p>Competitive inhibition with sympathomimetics</p> Signup and view all the answers

    In which scenario would a clinician likely prescribe Propranolol?

    <p>To manage hypertension or anxiety</p> Signup and view all the answers

    What potential side effect might be caused by the use of non-selective beta blockers like Propranolol?

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

    What physiological effect is primarily caused by non-selective alpha blockers due to increased norepinephrine release?

    <p>Enhanced cardiac stimulation</p> Signup and view all the answers

    What complication is commonly associated with postural hypotension when using non-selective alpha blockers?

    <p>Reflex tachycardia</p> Signup and view all the answers

    Why is the use of non-selective alpha blockers severely limited in treating essential hypertension?

    <p>They often lead to reflex tachycardia</p> Signup and view all the answers

    What type of receptors do non-selective alpha blockers antagonize to enhance norepinephrine release?

    <p>Presynaptic alpha-2 receptors</p> Signup and view all the answers

    Which of the following best describes the action of norepinephrine in the context of cardiac function?

    <p>It enhances cardiac stimulation</p> Signup and view all the answers

    What is a potential severe outcome of reflex tachycardia induced by non-selective alpha-blockers?

    <p>Cardiac arrhythmias</p> Signup and view all the answers

    Which condition might be affected by the use of non-selective alpha blockers?

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

    What impacts can postural hypotension have on patients taking non-selective alpha blockers?

    <p>Decreased cerebral perfusion</p> Signup and view all the answers

    In the context of adrenergic antagonists, what role do non-selective alpha blockers play?

    <p>Antagonize multiple adrenergic receptors</p> Signup and view all the answers

    Non-selective alpha blockers' ability to cause reflex tachycardia is primarily a result of what mechanism?

    <p>Increased sympathetic nerve activity</p> Signup and view all the answers

    Study Notes

    Adrenergic Antagonists

    • Alpha antagonists primarily target alpha receptors; exceptions include phentolamine, which binds equally to alpha 1 and alpha 2 receptors.
    • Yohimbine and tolazoline preferentially affect alpha 2 receptors over alpha 1.
    • Mixed antagonists like labetalol and carvedilol have significant affinities for both alpha and beta receptors but predominantly affect beta receptors.

    Beta Antagonists

    • Beta antagonists focus on blocking beta receptors, influencing cardiovascular responses, especially during exercise.
    • Propranolol blocks both β1 and β2 receptors; effects on bronchial smooth muscle are notable, with potential risks in patients with obstructive pulmonary diseases.
    • The presence of beta blockers can increase heart rate and myocardial contractility during exercise, though exercise-induced increases in cardiac output may be less affected due to higher stroke volume.

    Metabolic Effects

    • Beta antagonists alter carbohydrate and lipid metabolism, affecting glycogenolysis and glucose mobilization in response to hypoglycemia.

    Cardiac Effects

    • Non-selective alpha blockers can lead to enhanced norepinephrine release from cardiac nerves due to α2 receptor antagonism, causing postural hypotension and reflex tachycardia, which can result in cardiac arrhythmias.
    • These characteristics limit their use primarily for treating essential hypertension.

    Non-Selective Alpha Antagonists

    • Non-selective alpha antagonists inhibit norepinephrine and epinephrine from interacting with α and β adrenergic receptors, functioning mainly as competitive antagonists.
    • Phenoxybenzamine is an exception, acting as an irreversible antagonist by covalently binding to receptors.

    α2-Selective Antagonists

    • Selective blockade of α2 adrenergic receptors leads to increased sympathetic outflow and enhanced norepinephrine release, resulting in raised blood pressure through activation of α1 and β1 receptors.

    Specific Drug Information

    • Metoprolol has a greater affinity for β1 receptors, while butoxamine shows predominant affinity for β2 receptors.
    • Yohimbine is categorized as a prodrug affecting α2-adrenoceptors.

    Systolic Pressure and Myocardial Demand

    • Catecholamines elevate myocardial oxygen demand; patients with coronary artery disease can experience myocardial ischemia due to narrowed vessels.
    • Beta-adrenergic antagonists typically do not lower blood pressure in hypertensive patients as effectively.

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    Pharmacology Mod 1: Adrenergic Antagonists PDF

    Description

    Test your understanding of adrenergic antagonists, focusing on alpha and beta blockers. This quiz covers their mechanisms, receptor affinities, and metabolic effects. Perfect for students of pharmacology or anyone interested in cardiovascular pharmacotherapy.

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