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Pharmacology · single question

The mechanism of action of thiazide diuretics (e.g., hydrochlorothiazide) is:

  1. Inhibit Na/K/2Cl cotransporter in the loop of Henle
  2. Block aldosterone receptors in the collecting duct
  3. Inhibit Na-Cl cotransporter in the distal convoluted tubule → increase sodium and water excretion
  4. Inhibit carbonic anhydrase in the proximal tubule
Show answer and explanation

Correct answer: C. Inhibit Na-Cl cotransporter in the distal convoluted tubule → increase sodium and water excretion

  • A. Na/K/2Cl cotransporter inhibition is the mechanism of LOOP DIURETICS (furosemide, bumetanide).
  • B. Aldosterone receptor blockers are spironolactone, eplerenone — potassium-sparing diuretics.
  • C. Correct. Thiazide diuretics (hydrochlorothiazide, chlorthalidone) inhibit the Na-Cl cotransporter (NCC) in the DISTAL CONVOLUTED TUBULE, reducing sodium reabsorption and increasing urine output. A recognized side effect in dentistry: XEROSTOMIA (dry mouth) due to reduced salivary flow from general reduction in secretory fluid output.
  • D. Carbonic anhydrase inhibition is the mechanism of acetazolamide.

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