Dobutamine is used in cardiogenic shock to increase cardiac output. Its predominant mechanism of benefit is activation of which receptor?

• A Alpha-1 adrenoceptor, increasing systemic vascular resistance
• B Dopamine D1 receptor, causing renal vasodilation
• C Beta-1 adrenoceptor, increasing myocardial contractility ✓
• D Beta-2 adrenoceptor, causing bronchodilation

Explanation

Dobutamine is a synthetic catecholamine with predominant beta-1 agonist activity, producing positive inotropy with modest chronotropy and a slight decrease (via beta-2) in systemic vascular resistance—making it ideal in cardiogenic shock where raising contractility without markedly increasing afterload is desired. It does not act primarily on alpha-1 (minimal pressor effect) or D1 receptors (fenoldopam and dopamine at low dose mediate renal vasodilation via D1).

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

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