Pharmacology · patient case question
What is the mechanism of action of triamterene?
Patient case: Bone biology and drug mechanisms
Scenario: One histology item followed by a run of mechanism-of-action questions.
Show answer and explanation
Correct answer: B. Blocks sodium channels in the distal tubule, sparing potassium
- A. The Na-K-2Cl cotransporter is the target of loop diuretics such as furosemide, which waste potassium heavily.
- B. Correct. Triamterene blocks epithelial sodium channels in the distal tubule and collecting duct. Because potassium secretion is coupled to sodium reabsorption there, blocking sodium entry retains potassium — hence potassium-sparing.
- C. Acetazolamide inhibits carbonic anhydrase and is used for glaucoma and altitude sickness, not routine blood-pressure control.
- D. Spironolactone is the aldosterone receptor antagonist. It is also potassium-sparing but reaches the same endpoint by a different route.