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# Spironolactone (Aldactone)
## Overview
Spironolactone is a potassium-sparing diuretic and a competitive aldosterone antagonist. It works by blocking the effect of aldosterone in the distal tubules and collecting ducts of the nephron, leading to increased sodium and water excretion while conserving potassium.
## Primary Indications
* **Heart Failure:** To reduce mortality and hospitalizations in patients with symptomatic heart failure (NYHA class II-IV) with reduced ejection fraction, typically added to standard therapy.
* **Edema/Ascites:** Management of edema and ascites associated with congestive heart failure, cirrhosis of the liver, and the nephrotic syndrome.
* **Hypertension:** Adjunctive treatment of essential hypertension, particularly when hypokalemia is present or to enhance the effect of other diuretics.
* **Primary Hyperaldosteronism:** Diagnosis and treatment of hyperaldosteronism.
## Adult Dosing
* **Heart Failure:** Start at 25 mg once daily. May be titrated up to 50 mg once daily, or up to 100 mg once daily as tolerated and indicated. Target dose is typically 25-50 mg once daily.
* **Edema/Ascites (Cirrhosis):** Start at 100 mg once daily. Doses range from 25 mg to 400 mg daily, divided or once daily.
* **Hypertension:** Start at 25-100 mg once daily, divided or once daily. Doses can range up to 200 mg daily.
* **Primary Hyperaldosteronism:** Preoperative: 100-400 mg daily, divided or once daily. Long-term maintenance: 25-100 mg daily, divided or once daily.
## Pediatric Dosing
Dosing in children is highly variable and depends on weight and indication. Typical doses range from 1.5 mg/kg to 3 mg/kg per day, divided into 2-4 doses. Specific recommendations should be guided by expert consultation or reliable pediatric references and titrate to response and tolerance.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Monitor serum creatinine and potassium closely. Discontinue if serum creatinine rises significantly or if hyperkalemia develops.
* **Hepatic Impairment:** Use with caution, especially in severe impairment.
## Contraindications
* Anuria
* Acute renal insufficiency
* Significant impairment of renal excretory function
* Hyperkalemia
* Addison's disease
* Known hypersensitivity to spironolactone or its components
## Adverse Effects
* **Common:** Hyperkalemia, gynecomastia, menstrual irregularities, nausea, vomiting, diarrhea, abdominal cramping, drowsiness, lethargy, headache.
* **Less Common/Serious:** Hypotension, dehydration, hyponatremia, confusion, rash, Stevens-Johnson syndrome, toxic epidermal necrolysis, interstitial nephritis, renal failure.
## Key Drug Interactions
* **ACE Inhibitors, ARBs, Potassium Supplements, Other Potassium-Sparing Diuretics:** Increased risk of hyperkalemia. Monitor potassium closely.
* **NSAIDs:** May reduce the diuretic, natriuretic, and antihypertensive effects of spironolactone and increase the risk of hyperkalemia.
* **Potassium-Rich Foods/Salt Substitutes:** Increased risk of hyperkalemia.
* **Digoxin:** Spironolactone may increase digoxin levels and prolong its half-life.
* **Lithium:** Spironolactone may reduce renal clearance of lithium, increasing the risk of lithium toxicity.
* **Cholestyramine:** May increase the risk of hyperkalemia.
## Monitoring
* **Serum Potassium:** Regularly, especially with concomitant use of drugs that increase potassium, in renal impairment, and with dose changes.
* **Renal Function (BUN, Creatinine):** Regularly, especially in patients with pre-existing renal disease or those at risk.
* **Electrolytes (Sodium):** Regularly.
* **Blood Pressure:** Monitor for hypotension.
* **Gynecomastia/Breast Tenderness:** Assess in both males and females.
## Clinical Pearls
* Spironolactone's onset of action is gradual, and it may take several weeks to observe full diuretic or antihypertensive effects.
* Due to its anti-androgenic effects, gynecomastia is a common side effect, particularly at higher doses and in men.
* It is crucial to educate patients about the risk of hyperkalemia and to avoid potassium supplements and salt substitutes containing potassium unless specifically advised by their physician.
* When used for heart failure, it is typically added to conventional therapy (ACEI/ARB/ARNI, beta-blocker, MRA) and titrated carefully.
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*This information is intended for healthcare professionals. It is essential to consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions.*
