Aldosterone antagonists are a class of prescription medications that influence the body’s fluid and electrolyte balance by counteracting a specific hormone. This article explains how they function, the conditions they address, and practical considerations for those taking them.
Aldosterone’s Role in the Body
Aldosterone, a steroid hormone from the adrenal glands, regulates blood pressure, fluid balance, and sodium/potassium levels. It is a key component of the renin-angiotensin-aldosterone system (RAAS), maintaining blood pressure stability.
Aldosterone signals kidneys to reabsorb sodium, leading to water retention, increased blood volume, and higher blood pressure. It also promotes potassium excretion, balancing electrolyte levels.
Normally, aldosterone helps the body adapt to changes in blood volume or pressure. However, elevated or dysregulated aldosterone can lead to high blood pressure, fluid retention, and potassium imbalances, negatively affecting the heart and kidneys.
How Aldosterone Antagonists Work
Aldosterone antagonists (MRAs) block aldosterone’s action by binding to and deactivating mineralocorticoid receptors in the kidneys, heart, and blood vessels. This prevents aldosterone from exerting its effects.
In the kidneys, these medications increase sodium and water excretion, reducing fluid volume. Unlike other diuretics, they promote potassium retention, beneficial given aldosterone’s role in potassium excretion.
Beyond fluid and electrolyte effects, aldosterone antagonists mitigate harmful effects of prolonged aldosterone overactivity, including reducing fibrosis (tissue scarring) in the heart and blood vessels. Spironolactone and eplerenone are the main medications in this class.
Conditions Treated by Aldosterone Antagonists
Aldosterone antagonists are prescribed for several medical conditions where excessive aldosterone activity contributes to disease progression.
One primary use is in the management of heart failure, especially in patients with reduced ejection fraction. These drugs help to reduce fluid buildup, ease the heart’s workload, and improve outcomes by preventing adverse cardiac remodeling and fibrosis.
They also treat hypertension, especially resistant hypertension, where high blood pressure persists despite multiple medications. Elevated aldosterone often contributes to this, and antagonists can significantly reduce blood pressure, even without overt hyperaldosteronism.
Another application is treating ascites, fluid accumulation in the abdomen often linked to liver cirrhosis. In cirrhosis, increased aldosterone causes severe sodium retention and fluid overload, making antagonists like spironolactone a primary treatment choice. They promote sodium excretion and reduce fluid accumulation.
Taking Aldosterone Antagonists
Individuals prescribed aldosterone antagonists should be aware of potential side effects and the need for regular monitoring.
A common concern is hyperkalemia (elevated blood potassium), as these medications promote potassium retention. This risk is higher for individuals with kidney disease.
Regular blood tests monitor potassium levels and kidney function, especially when starting or adjusting the dose. Some men taking spironolactone may experience gynecomastia (breast swelling or tenderness) due to the drug’s interaction with other hormone receptors.
Aldosterone antagonists are prescription-only. Healthcare providers determine dosage and duration. Adhere to the regimen and communicate side effects to your clinician. Avoid potassium-containing salt substitutes, as they increase hyperkalemia risk.