What is a sodium-sparing diuretic?

From the Guidelines

Sodium-sparing diuretics, specifically spironolactone, should be used as the first-line treatment for patients with ascites due to liver cirrhosis, starting at a dose of 50-100 mg/day, as recommended by the most recent guidelines 1.

Key Points

• Sodium-sparing diuretics are used to treat conditions like heart failure, liver cirrhosis with ascites, and hypertension.
• The main types of sodium-sparing diuretics include potassium-sparing diuretics (spironolactone, eplerenone, amiloride, and triamterene) and carbonic anhydrase inhibitors (acetazolamide).
• Spironolactone is typically started at 50-100 mg/day, while eplerenone begins at 25mg daily, as per the guidelines for liver cirrhosis with ascites 1.
• Amiloride is usually prescribed at 5-10mg daily, and triamterene at 50-100mg daily, but their use may be limited due to side effects and interactions.
• These medications work by blocking aldosterone receptors or sodium channels in the distal tubules of the kidneys, preventing sodium reabsorption and potassium excretion.
• Regular monitoring of electrolytes and kidney function is essential when using these medications, especially in patients with kidney dysfunction, to prevent hyperkalemia.

Treatment Considerations

• Loop diuretics, such as furosemide, can be used in combination with spironolactone for patients with resistant ascites or those who require a more rapid diuresis 1.
• The dose of spironolactone should be adjusted based on the patient's response and serum potassium levels, with a maximum dose of 400 mg/day 1.
• Patients with hepatic encephalopathy, hyponatremia, or acute kidney injury should be closely monitored and may require adjustments to their diuretic regimen 1.

Recent Guidelines

• The 2024 ESC guidelines for the management of elevated blood pressure and hypertension recommend the use of spironolactone as an add-on therapy for patients with resistant hypertension 1.
• The 2018 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults also recommends the use of spironolactone for patients with resistant hypertension 1.
• The 2012 ESC guidelines for the diagnosis and treatment of acute and chronic heart failure recommend the use of diuretics, including spironolactone, for patients with heart failure and signs of congestion 1.

From the FDA Drug Label

Amiloride HCl exerts its potassium sparing effect through the inhibition of sodium reabsorption at the distal convoluted tubule, cortical collecting tubule and collecting duct; this decreases the net negative potential of the tubular lumen and reduces both potassium and hydrogen secretion and their subsequent excretion

• Sodium sparing diuretic is another term for potassium sparing diuretic, as it spares potassium by inhibiting sodium reabsorption.
• The drug amiloride is an example of a sodium sparing diuretic, as stated in the drug label 2.
• Triamterene is also a potassium-sparing diuretic, but the label does not explicitly describe its mechanism of action as sodium sparing 3.

From the Research

Sodium-Sparing Diuretics

• Sodium-sparing diuretics, such as spironolactone, are used to treat resistant hypertension and other conditions like heart failure and edema in patients with cirrhosis 4, 5.
• These diuretics work by antagonizing aldosterone, which helps to reduce blood pressure and alleviate symptoms of heart failure 4, 5.
• Spironolactone has been shown to be effective in lowering blood pressure in patients with resistant hypertension, with an average reduction of 22/10 mm Hg 4.

Types of Diuretics

• There are different types of diuretics, including thiazide diuretics, loop diuretics, and potassium-sparing diuretics 6, 7.
• Thiazide diuretics are commonly used to treat hypertension, but other types of diuretics may be more effective in certain situations, such as chronic kidney disease 6.
• Potassium-sparing diuretics, like spironolactone, are useful in treating conditions where potassium loss is a concern 4, 5.

Efficacy and Safety

• Spironolactone has been compared to other mineralocorticoid receptor antagonists, such as eplerenone, in terms of efficacy and tolerability in patients with resistant hypertension 8.
• While eplerenone may be better tolerated, spironolactone has been shown to be more effective in lowering blood pressure in these patients 8.
• Both spironolactone and eplerenone require close monitoring of potassium levels and renal function to minimize the risk of adverse effects 8.