Potassium-Sparing Diuretics

Question 1

Spironolactone
MOA

Answer 1

Direct antagonists of aldosterone: Competes with aldosterone for intracellular receptors preventing binding with mineralocorticoid receptor, inhibiting Na+ reabsorption in distal nephron

Question 2

Spironolactone
Abs/Distrb/Elim

Answer 2

Orally
Half life 11.2 hrs
Slow onset 2-3 days
Often given with thiazide or loop diuretics

Question 3

Spironolactone
Clinical use

Answer 3

Hypertension
Hyperaldosteronism

Question 4

Spironolactone
Adverse eects

Answer 4

Hyperkalemia
Gynaecomastia
Erectile dysfunction
Menstrual disorders

Question 5

Amiloride
MOA

Answer 5

Blocks luminal Na channels in the apical membrane of the cortical collecting ducts of the nephron, inhibiting Na reabsorption, indirectly reduces K+ excretion

Question 6

Amiloride
Abs/Distrb/Elim

Answer 6

Oral
Effects 2hrs
Last 24hrs

Question 7

Amiloride
Clinical use

Answer 7

Hypertension
Oedema - combined with thiazide and loop diuretics
Hypokalemia

Question 8

Amiloride
Adverse effects

Answer 8

Hyperkalaemia; may cause acidosis.