Name two diuretics commonly used in heart failure and their primary actions.

• A. Hydrochlorothiazide — loop diuretic; Furosemide — thiazide
• B. Spironolactone — potassium-sparing; Furosemide — thiazide
• C. Furosemide (loop) inhibits Na-K-2Cl; Hydrochlorothiazide (thiazide) inhibits Na-Cl reabsorption
• D. Indapamide — inhibits carbonic anhydrase; Bumetanide — inhibits ACE

Answer: (C)

In heart failure, easing fluid overload comes from diuretics that act at different parts of the nephron to promote sodium and water excretion. A loop diuretic like furosemide targets the thick ascending limb, where the Na-K-2Cl cotransporter resides. By blocking this transporter, it prevents the reabsorption of sodium, potassium, and chloride, producing a strong diuretic effect that rapidly reduces edema and congestion.

A thiazide diuretic such as hydrochlorothiazide works on the distal convoluted tubule, inhibiting the Na-Cl cotransporter. This yields a more moderate diuresis and is often used for longer-term control and can be added to loop diuretics to enhance diuresis or counter diuretic resistance.

So, pairing a loop diuretic with its action (Na-K-2Cl inhibition in the loop) and a thiazide with its action (Na-Cl inhibition in the distal tubule) correctly captures two commonly used diuretics in heart failure and their primary mechanisms.

The other options mix up drugs with incorrect mechanisms (for example, labeling loop diuretics as thiazides or misassigning actions like carbonic anhydrase inhibition or ACE inhibition), which doesn’t fit how these agents work in practice.