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Question 455
Pharmacology → General
Classification
Question
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A patient receives a mild natriuretic that acts in the distal nephron and conserves potassium by inhibiting renal epithelial sodium channels. Which pair of drugs has this mechanism?
Question Stem
Select the single best answer.
Options
A
Furosemide and bumetanide
B
Metolazone and bendroflumethiazide
C
Mannitol and urea
D
Triamterene and amiloride
E
Torsemide and furosemide
Explanation
Triamterene and amiloride are renal epithelial sodium-channel inhibitors within the potassium-sparing diuretic group. They act distally, producing mild natriuresis while indirectly conserving potassium. This mechanism is distinct from loop-diuretic Na-K-2Cl inhibition and thiazide Na-Cl inhibition.
Option Validity
A) Furosemide and bumetanide are loop diuretics that inhibit Na-K-2Cl cotransport in the ascending limb.
B) Metolazone and bendroflumethiazide are thiazide diuretics acting through inhibition of Na-Cl symport.
C) Mannitol and urea are osmotic diuretics.
E) Torsemide and furosemide are loop diuretics rather than epithelial sodium-channel inhibitors.
Further Reading
Saxena R. Textbook for MRCOG-1. Chapter 12: Pharmacology. Diuretics, pp.347–348.