Which of the following is a loop diuretic used in heart failure?

• A. Furosemide
• B. Lisinopril
• C. Metoprolol
• D. Amlodipine

Answer: (A)

Reducing fluid overload is central to managing heart failure, and loop diuretics are the most potent option for that purpose. Furosemide is a loop diuretic, blocking the Na-K-2Cl cotransporter in the thick ascending limb of the loop of Henle. This causes large amounts of salt and water to be excreted (natriuresis and diuresis), lowering preload and relieving edema and pulmonary congestion.

The other drugs listed serve different roles in heart failure or are not diuretics: an ACE inhibitor reduces afterload and remodeling, a beta-blocker lowers heart rate and myocardial demand, and a calcium channel blocker mainly dilates vessels without providing diuresis. Hence, the loop diuretic used in heart failure among these options is furosemide.