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# Spironolactone
## Overview
Spironolactone is a potassium-sparing diuretic and a competitive aldosterone antagonist. It inhibits the action of aldosterone in the distal tubules, leading to increased sodium and water excretion and potassium retention.
## Primary Indications
* Heart Failure (NYHA class II-IV) with reduced ejection fraction
* Edema associated with cirrhosis or nephrotic syndrome
* Essential hypertension
* Primary hyperaldosteronism
## Adult Dosing
* **Heart Failure:** 25 mg orally once daily, titrate to 25 mg or 50 mg orally once or twice daily. Maximum dose: 100 mg/day.
* **Cirrhosis with Edema/Ascites:** 25 mg to 100 mg orally once daily. Maximum dose: 400 mg/day.
* **Essential Hypertension:** 25 mg to 100 mg orally once daily. May be combined with other antihypertensives. Maximum dose: 400 mg/day.
* **Primary Hyperaldosteronism:** 100 mg to 400 mg orally/day, divided doses.
## Pediatric Dosing
* **Edema/Ascites:** 1.5 mg/kg to 3 mg/kg orally per day, divided into 2 to 4 doses. Maximum dose: 100 mg/day or 3.3 mg/kg/day.
* **Hypertension:** 1 mg/kg to 2 mg/kg orally per day, divided into 2 to 4 doses. Maximum dose: 3.3 mg/kg/day or 100 mg/day.
Dosing in children is less well-established and should be guided by response and tolerance.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Avoid in severe renal impairment. Monitor potassium closely.
* **Hepatic Impairment:** Use with caution due to risk of hepatic encephalopathy.
## Contraindications
* Anuria
* Acute renal insufficiency
* Significant Impaired Renal Function (e.g., CrCl < 30 mL/min)
* Hyperkalemia (serum potassium > 5.0 mEq/L)
* Addison's disease
* Known hypersensitivity to spironolactone
## Adverse Effects
* Hyperkalemia (most serious)
* Gynecomastia and breast tenderness (men)
* Menstrual irregularities, breast enlargement (women)
* Nausea, vomiting, diarrhea
* Dizziness, headache
* Lethargy
* Gastric upset
* Hirsutism, deepening of voice (women)
## Key Drug Interactions
* **ACE Inhibitors, ARBs, NSAIDs, Potassium Supplements, Salt Substitutes:** Increased risk of hyperkalemia.
* **Potassium-Sparing Diuretics:** Additive effect, increased risk of hyperkalemia.
* **Lithium:** Spironolactone can decrease lithium clearance, increasing lithium toxicity risk.
* **Digoxin:** Spironolactone may increase digoxin levels.
## Monitoring
* **Serum Electrolytes:** Especially potassium, at baseline and regularly during therapy.
* **Renal Function:** Serum creatinine and BUN at baseline and periodically.
* **Blood Pressure:** Particularly when used for hypertension.
* **Signs and Symptoms of Hyperkalemia:** (e.g., muscle weakness, palpitations, fatigue).
* **Signs of Gynecomastia/Endocrine Effects.**
## Clinical Pearls
* Take with food to increase absorption and decrease gastrointestinal upset.
* To minimize endocrine side effects, consider using the lowest effective dose and giving it as a single daily dose if possible.
* Due to its mechanism, therapeutic effects may take several days to weeks to become fully apparent.
* Consider spironolactone in patients with resistant hypertension.
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*This information is intended for healthcare professionals and does not substitute for comprehensive drug information resources. Always verify current prescribing information and guidelines before use.*
