From the Guidelines
Potassium-sparing diuretics are a class of medications that help the body get rid of excess fluid while preserving potassium levels, and they are commonly used to treat conditions such as hypertension, heart failure, and edema. The main types of potassium-sparing diuretics are aldosterone antagonists (spironolactone and eplerenone), epithelial sodium channel blockers (amiloride and triamterene), and sodium-potassium exchange inhibitors.
- The typical dosages for these medications are:
- Spironolactone: 25-100 mg daily for hypertension or heart failure 1
- Eplerenone: 25-50 mg daily 1
- Amiloride: 5-10 mg daily 1
- Triamterene: 50-100 mg daily 1 These medications work by blocking aldosterone receptors or sodium channels in the distal tubule and collecting duct of the kidney, which prevents sodium reabsorption and potassium excretion.
- The common uses of potassium-sparing diuretics include:
- Treating hypertension
- Managing heart failure
- Reducing edema
- Treating primary hyperaldosteronism
- Counteracting potassium loss caused by other diuretics It is essential to monitor potassium levels regularly in patients taking these medications, as hyperkalemia is a potential side effect 1.
- Additionally, potassium-sparing diuretics should be used cautiously in patients with kidney dysfunction and are contraindicated in those with severe renal impairment or high potassium levels 1.
From the FDA Drug Label
Triamterene Capsules are potassium-sparing diuretics. Eplerenone tablets may be used alone or in combination with other antihypertensive agents. The recommended starting dose of eplerenone tablets is 50 mg administered once daily. When used alone, the usual starting dose is 100 mg twice daily after meals.
Potassium-sparing diuretics include:
- Eplerenone
- Triamterene
Typical dosages:
- Eplerenone: 50 mg once daily, with a maximum of 50 mg twice daily for hypertension, and 25-50 mg once daily for heart failure post-myocardial infarction
- Triamterene: 100 mg twice daily after meals, with a maximum of 300 mg per day
Common uses:
From the Research
Potassium-Sparing Diuretics
- Potassium-sparing diuretics are a group of drugs that have "weak diuretic" properties and are beneficial in patients with cirrhosis and ascites, as well as in treating hypertension and certain diseases such as Conn's, Bartter's, and Liddle syndromes 4.
- They work by avoiding potassium loss and can potentiate the effects of other diuretics, and can be combined with each other or with ACE inhibitors 4.
Typical Dosages and Effects
- The typical dosages and effects of potassium-sparing diuretics vary, with studies showing that doubling the dose of amiloride, eplerenone, and spironolactone can reduce systolic blood pressure by an average of -2.3 mmHg 5.
- The relative antihypertensive potencies of these drugs are spironolactone > amiloride > eplerenone, with dose equivalencies of eplerenone-spironolactone 4.5-to-1, amiloride-spironolactone 3.3-to-1, and eplerenone-amiloride 1.4-to-1 5.
- Increases in serum potassium from amiloride and spironolactone at commonly used doses average 0.14-0.29 mEq/l, with spironolactone causing greater hyperkalemia than amiloride across their dose ranges 5.
Mechanism of Action
- Potassium-sparing diuretics act on the distal parts of the nephron, from the late distal tubule to the collecting duct, by blocking the luminal membrane sodium channel or inhibiting the action of aldosterone 6.
- Amiloride and triamterene reduce sodium transport by blocking the luminal membrane sodium channel, while spirolactones are competitive inhibitors of aldosterone, which promotes sodium reabsorption 6.
- The inhibitory effect on the electrogenic sodium transport decreases the lumen-negative transepithelial potential difference, reducing the driving force for potassium movement into the tubular lumen and thus decreasing potassium excretion 6.