Which of the following is a carbonic anhydrase inhibitor?

Carbonic anhydrase inhibitors are a specific class of diuretics that work primarily in the renal proximal tubules. They inhibit the enzyme carbonic anhydrase, which plays a crucial role in the rehydration of carbon dioxide and the formation of bicarbonate from carbon dioxide and water. This inhibition leads to decreased reabsorption of bicarbonate, resulting in increased excretion of bicarbonate, sodium, and water into the urine, ultimately leading to a diuretic effect.

Acetazolamide is well-known as a carbonic anhydrase inhibitor, making it the correct choice in this question. It is frequently used not only for its diuretic properties but also in the treatment of conditions such as glaucoma, altitude sickness, and certain types of metabolic alkalosis.

In contrast, the other options listed are loop diuretics. Torsemide, furosemide, and bumetanide primarily inhibit the Na-K-2Cl transporter in the thick ascending limb of the loop of Henle, leading to a different mechanism of action and a distinct set of therapeutic uses. These diuretics are more potent for rapid diuresis compared to carbonic anhydrase inhibitors but operate through a different pathway. Thus, their classification as