Potassium-Sparing Diuretics in Clinical Practice

Pharmacokinetics and Pharmacodynamics

The European Society of Cardiology recommends that amiloride has a maximum plasma concentration of 3-4 hours and a plasma half-life of 6-9 hours 1
The American Heart Association notes that amiloride is not metabolized by the liver, but is excreted unchanged by the kidneys, with 50% of a 20 mg dose excreted in urine and 40% in feces within 72 hours 1

The European Society of Cardiology suggests that potassium-sparing diuretics, such as amiloride, are indicated for the prevention of hypokalemia in patients receiving thiazide or loop diuretics 1
The American College of Cardiology recommends that potassium-sparing diuretics be used in combination with thiazide or loop diuretics to reduce the risk of hypokalemia and hypomagnesemia 1

The European Society of Cardiology advises that potassium-sparing diuretics should be avoided in patients with significant chronic kidney disease (eGFR <45 mL/min) due to the increased risk of hyperkalemia 1
The American Heart Association notes that potassium-sparing diuretics are contraindicated in patients with baseline serum potassium >5.0 mEq/L, and that concomitant use with ACE inhibitors or ARBs requires careful monitoring 1

The European Society of Cardiology recommends that serum potassium and creatinine be checked 5-7 days after initiating therapy with potassium-sparing diuretics, and then every 5-7 days until values stabilize 1
The American College of Cardiology suggests that if serum potassium exceeds 5.5 mEq/L, the dose of potassium-sparing diuretic should be reduced by half and rechecked in 1-2 weeks 1

The European Society of Cardiology notes that potassium-sparing diuretics offer more stable potassium levels without the fluctuations associated with oral supplementation, and address ongoing renal losses more effectively 1
The American Heart Association recommends that potassium-sparing diuretics reduce the increased magnesium excretion that occurs with thiazide or loop diuretics alone, and can potentiate the effects of diuretics acting in the distal tubules and Henle's loop 1

The American College of Cardiology and the American Heart Association recommend the use of potassium-sparing diuretics, such as spironolactone and eplerenone, to prevent hypokalemia in patients receiving thiazide diuretics 2, 3
Potassium-sparing diuretics are useful in primary hyperaldosteronism and resistant hypertension, according to the American College of Cardiology 2, 3

The American Heart Association classifies potassium-sparing diuretics into two main groups: antagonists of mineralocorticoid receptors (ARM) and blockers of epithelial sodium channels, with spironolactone and eplerenone being examples of ARM 2, 4
The European Society of Cardiology notes that eplerenone has a more selective action on mineralocorticoid receptors, resulting in fewer side effects compared to spironolactone 5

The European Heart Journal reports that spironolactone has an oral bioavailability of 60-90% and is extensively metabolized in the liver, with a half-life of 1-2 hours for the parent compound and 12-24 hours for its active metabolites 6
The American College of Cardiology states that eplerenone has an oral bioavailability of 69% and is metabolized in the liver via CYP3A4, with a half-life of 4-6 hours 2, 5

The American Heart Association recommends the use of potassium-sparing diuretics as adjunctive therapy in resistant hypertension, with spironolactone being a preferred agent due to its efficacy in reducing blood pressure 2, 3
The European Society of Cardiology suggests that eplerenone is an alternative to spironolactone in patients who experience sexual side effects, with a dosage of 50-100 mg/day 5

The American College of Cardiology advises against the use of potassium-sparing diuretics in patients with significant chronic kidney disease (eGFR <45 mL/min) due to the risk of hyperkalemia 2, 3
The European Heart Journal recommends monitoring potassium levels and renal function closely when initiating therapy with potassium-sparing diuretics, especially when combined with ACE inhibitors or ARBs 7, 6