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Questions and Answers
What is the primary indication for the use of dobutamine?
What is the principal hemodynamic effect of dobutamine?
What type of receptor does dobutamine primarily activate?
What is the mechanism by which dobutamine increases cardiac output?
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What is the class of medication to which dobutamine belongs?
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Acute administration of β-receptor antagonists can precipitate congestive heart failure in patients with multiple forms of heart disease.
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Chronic administration of β-receptor antagonists is not efficacious in prolonging life in the therapy of heart failure.
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β-Receptor antagonists are not useful in the treatment of chronic open-angle glaucoma.
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Propranolol is not used as an adjuvant in the treatment of hyperthyroidism.
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Metoprolol is not used in the prophylaxis of migraine.
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All α-receptor antagonists are reversible.
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Phenoxybenzamine is a reversible α blocker.
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Phenoxybenzamine blocks only α1 receptors.
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Phenoxybenzamine does not cause postural hypotension with dizziness.
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Phenoxybenzamine does not cause miosis.
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Study Notes
Dobutamine in CHF Management
- Dobutamine is the β agonist of choice for managing patients with systolic dysfunction and congestive heart failure (CHF).
- The primary hemodynamic effect of dobutamine is to increase stroke volume, which it achieves through its positive inotropic action.
Sympathomimetics and Sympatholytics
Synthesis, Release, and Metabolism of Catecholamine
- Not actually sympathetic drugs but produce sympathomimetic-like effect
Direct Acting Nonselective Agonists
- Epinephrine (adrenaline): α and β agonist, potent vasoconstrictor and cardiac stimulant
- Isoproterenol: nonselective β agonist
- Oxymetazoline: nonselective α agonist, used as topical decongestant
Direct Acting Selective Adrenergic Receptor Agonists
- Terbutaline, Albuterol (Salbutamol): selective β2 agonist, bronchodilator
- Dobutamine: selective β1 agonist, used for management of patients with systolic dysfunction and CHF
- Phenylephrine: selective α1 receptor agonist
- Clonidine: selective α2 agonist, used primarily for systemic hypertension
Selective β1 Adrenergic Receptor Antagonists
- Atenolol: very hydrophilic, incompletely absorbed, and excreted largely unchanged in urine
- Metoprolol: almost completely absorbed, half-life 3-4 hours
- Esmolol: very short duration of action, administered intravenously
- Bisoprolol: highly selective β1 antagonist, generally well tolerated
α/β Antagonists/Blockers
- Labetalol: blocks β1, β2, and α1 receptors, has membrane stabilizing activity
- Carvedilol: blocks β1, β2, and α1 receptors, has antioxidant and anti-proliferative effects
Therapeutic Uses of β Blockers
- Cardiovascular diseases: hypertension, angina, acute coronary syndromes, supraventricular and ventricular arrhythmias, myocardial infarction
- Congestive Heart Failure: chronic administration is efficacious in prolonging life in the therapy of heart failure
- Glaucoma: β-receptor antagonists are useful in the treatment of chronic open-angle glaucoma
- Hyperthyroidism: β-blockers control many of the cardiovascular signs and symptoms
- Migraine: Propranolol, timolol, and metoprolol are used for prophylaxis
α Receptor Blockers
- Reversible antagonists: Phentolamine and prazosin
- Irreversible antagonists: Phenoxybenzamine covalently binds to α-receptors, resulting in irreversible blockade
Nonselective α Blockers
- Phenoxybenzamine: blocks α1 and α2 receptors, irreversibly in smooth muscle and other sites
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Description
This quiz covers the use of β agonists, specifically dobutamine, in the management of patients with systolic dysfunction and chronic heart failure (CHF). It explores the principal hemodynamic effects of dobutamine on stroke volume.
