From the Guidelines
Spironolactone is the preferred choice over losartan for patients with heart failure due to its proven mortality benefits, as demonstrated in the RALES trial 1. The use of spironolactone in patients with severe heart failure has been shown to reduce the risk of death and hospitalization due to heart failure by 30% and 35%, respectively, as compared to conventional treatment alone 1.
Key Benefits of Spironolactone
- Reduces mortality and morbidity in patients with heart failure with reduced ejection fraction
- Effective in treating conditions like primary hyperaldosteronism, resistant hypertension, and edematous conditions
- Offers additional benefits for women with PCOS or hirsutism due to its anti-androgenic effects
Dosage and Monitoring
The typical starting dose of spironolactone is 25 mg daily, which can be titrated up to 50 mg daily based on response and potassium levels, as outlined in Table 14 Evidence-based doses of disease-modifying drugs used in key randomized trials in heart failure 1.
Important Considerations
- Requires careful monitoring of potassium levels and renal function, especially when combined with other potassium-sparing medications or in patients with renal impairment
- Common side effects include hyperkalemia, gynecomastia in men, and menstrual irregularities in women In contrast, losartan, an angiotensin II receptor blocker, may be preferred in patients who cannot tolerate spironolactone's side effects or who have specific indications for ARB therapy, but it does not offer the same level of mortality benefit as spironolactone in patients with heart failure 1.
From the FDA Drug Label
1 INDICATIONS AND USAGE
Spironolactone tablets are indicated for treatment of NYHA Class III-IV heart failure and reduced ejection fraction to increase survival, manage edema, and reduce the need for hospitalization for heart failure. Spironolactone tablets are indicated as add-on therapy for the treatment of hypertension, to lower blood pressure in patients who are not adequately controlled on other agents.
The choice of spironolactone over losartan may be due to the following reasons:
- Heart failure: Spironolactone is indicated for the treatment of NYHA Class III-IV heart failure, which may not be the primary indication for losartan.
- Hypertension: Spironolactone can be used as add-on therapy for hypertension, and its mechanism of action as a potassium-sparing diuretic may be beneficial in certain patients.
- Edema: Spironolactone is also indicated for the management of edema associated with hepatic cirrhosis or nephrotic syndrome, which may not be a primary indication for losartan. However, without more information about the specific patient and their condition, it is difficult to make a definitive statement about why spironolactone was chosen over losartan 2.
From the Research
Comparison of Spironolactone and Losartan
- Spironolactone is an aldosterone antagonist that has been shown to be effective in treating heart failure with reduced ejection fraction, resistant hypertension, and edema in patients with cirrhosis 3, 4, 5.
- Losartan, on the other hand, is a selective angiotensin II type 1 (AT1) receptor antagonist that has been used to treat heart failure and hypertension 6.
Efficacy of Spironolactone
- Studies have demonstrated that spironolactone can improve morbidity and mortality in patients with heart failure, particularly those with resistant hypertension 4, 5.
- Spironolactone has also been shown to be effective in reducing hospitalizations in patients with heart failure with preserved ejection fraction 4.
Safety and Tolerability of Spironolactone
- While spironolactone can be safe and effective, it can also increase the risk of hyperkalemia, particularly in patients with chronic kidney disease 7.
- However, a study found that spironolactone may be safe to initiate in hospitalized patients with heart failure and chronic kidney disease, as long as appropriateness of therapy is assessed upon admission 7.
Comparison with Losartan
- Losartan has been shown to be effective in treating heart failure and hypertension, and has a similar mechanism of action to spironolactone in terms of blocking the effects of angiotensin II 6.
- However, the two drugs have different pharmacokinetic and pharmacodynamic profiles, which may result in differences in clinical profiles 6.