Which pair of drugs are calcium channel blockers?

• A. Lisinopril and Losartan
• B. Furosemide and hydrochlorothiazide
• C. Amlodipine and nifedipine
• D. Metoprolol and Propranolol

Answer: (C)

Calcium channel blockers work by blocking L-type calcium channels in vascular smooth muscle and heart, which leads to arterial dilation and decreased myocardial workload. The dihydropyridine calcium channel blockers, such as amlodipine and nifedipine, are especially known for causing arterial vasodilation and lowering blood pressure, so they are classified as calcium channel blockers. The other drugs operate by different mechanisms: lisinopril and losartan inhibit the renin-angiotensin system; furosemide and hydrochlorothiazide are diuretics that reduce fluid volume; metoprolol and propranolol are beta-adrenergic blockers that diminish heart rate and contractility. Therefore, the pair that fits calcium channel blockers is amlodipine and nifedipine.