Question

What is the site of action of the potassium-sparing diuretics?

(a) Proximal tubule

(b) Glomerulus

(c) Descending loop of Henle

(d) Distal tubule

The question was posed to me in a job interview.

I want to ask this question from Diuretics topic in chapter Applications of Pharmacokinetic Principles, Diuretics, Drug Concentration and Pharmacologic Response of Drug Biotechnology

Answer 1

Correct answer is (d) Distal tubule

Easy explanation: Potassium-sparing diuretics work in collecting ducts and distal convoluted tubules. It interferes with sodium-potassium exchange, competitively bind to aldosterone receptors, and block the resorption of sodium and water usually induced by aldosterone. Prevent potassium from being pumped into the tubule, thus preventing its secretion. Competitively block the aldosterone receptors and inhibit its action thus the excretion of sodium and water is promoted.