Which of the following is an example of a loop diuretic?

Furosemide is an example of a loop diuretic, which is a class of medications that primarily act on the ascending loop of Henle in the nephron of the kidney. These diuretics are highly effective in promoting the excretion of sodium and water, leading to increased urine output.

Loop diuretics, such as furosemide, are used in clinical practice to manage conditions like heart failure, renal impairment, and hypertension, as they are capable of producing a profound diuresis. Furosemide works by inhibiting the sodium-potassium-chloride (Na-K-2Cl) co-transporter, which leads to the loss of significant amounts of sodium, potassium, and chloride, as well as water.

The other medications listed do not fall under the classification of loop diuretics. Hydrochlorothiazide is a thiazide diuretic, which works on the distal convoluted tubule and has a different mechanism and efficacy profile. Spironolactone is a potassium-sparing diuretic that works by antagonizing aldosterone, thus preventing sodium reabsorption while retaining potassium. Amiloride is also a potassium-sparing diuretic that operates in the distal nephron.