Start practicing

Pharmacology · single question

What is the mechanism of action of metoprolol?

  1. Blocks calcium channels
  2. Decreases heart myocardial contractility (selective β1 beta-adrenergic blocker)
  3. Blocks α1 receptors (vasodilation)
  4. Inhibits ACE
Show answer and explanation

Correct answer: B. Decreases heart myocardial contractility (selective β1 beta-adrenergic blocker)

  • A. Calcium channel blockade is the mechanism of verapamil, diltiazem (CCBs) — not metoprolol.
  • B. Metoprolol is a SELECTIVE β1-ADRENERGIC RECEPTOR BLOCKER. By blocking β1 receptors in the HEART, it DECREASES heart rate (negative chronotropy), DECREASES myocardial contractility (negative inotropy), and DECREASES blood pressure. Being β1-selective, it has minimal effect on β2 receptors (bronchioles), making it safer in mild asthma compared to non-selective beta-blockers like propranolol.
  • C. α1 blockade (vasodilation) is the mechanism of alpha-blockers (prazosin) — not beta-blockers like metoprolol.
  • D. ACE inhibition is the mechanism of lisinopril/enalapril — not metoprolol.

Practice Pharmacology questions Pharmacology study notes

More Pharmacology practice questions