Pharmacology · single question

What is the mechanism by which amlodipine lowers blood pressure?

It increases cardiac output
It inhibits angiotensin-converting enzyme
It blocks calcium influx into vascular smooth muscle, causing vasodilation and reducing cardiac workload
It blocks beta-1 adrenergic receptors in the heart

Show answer and explanation

Correct answer: C. It blocks calcium influx into vascular smooth muscle, causing vasodilation and reducing cardiac workload

A. Antihypertensives reduce, not increase, cardiac workload.
B. ACE inhibition describes lisinopril and enalapril (and explains their dry cough and angioedema).
C. CORRECT. Amlodipine is a DIHYDROPYRIDINE calcium channel blocker. It preferentially blocks L-type calcium channels in VASCULAR SMOOTH MUSCLE, producing arterial vasodilation, reduced peripheral resistance, and therefore reduced afterload and cardiac workload. Dihydropyridines have minimal direct cardiac effect, unlike verapamil and diltiazem. The dental relevance: gingival ENLARGEMENT is a recognized adverse effect of calcium channel blockers, and ankle edema and reflex tachycardia are common.
D. Beta-1 blockade describes metoprolol and atenolol.

Note: Drugs causing gingival enlargement: phenytoin, cyclosporine, and calcium channel blockers (nifedipine, amlodipine, verapamil, diltiazem).

More Pharmacology practice questions