Which of the following is NOT a beta blocker?

• A. Propranolol
• B. Metoprolol
• C. Atenolol
• D. Doxazosin

Answer: (D)

The key idea is recognizing which drugs block beta-adrenergic receptors versus other receptors. Beta blockers work by antagonizing beta receptors, mainly reducing heart rate, contractility, and overall cardiac workload. Propranolol is a nonselective beta blocker, blocking multiple beta receptors. Metoprolol and atenolol are cardioselective beta-1 blockers, mainly affecting the heart.

Doxazosin is not a beta blocker. It targets alpha-1 receptors, causing vasodilation and lower peripheral resistance. It’s used for hypertension and benign prostatic hyperplasia, but it does not block beta receptors.