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# Aldactone (spironolactone) ## Overview Spironolactone is a potassium-sparing diuretic and a competitive aldosterone receptor antagonist. It acts primarily in the distal renal tubules to promote sodium and water excretion while retaining potassium. ## Primary Indications * **Heart Failure (NYHA Class II-IV):** To increase survival and reduce hospitalizations. * **Edematous states:** Cirrhosis with ascites, nephrotic syndrome. * **Primary Hyperaldosteronism:** Diagnosis and chronic management. * **Essential Hypertension:** Usually as add-on therapy. ## Adult Dosing * **Heart Failure:** Initial 12.5–25 mg once daily; target dose 25–50 mg daily. * **Edema (Cirrhosis/Nephrotic Syndrome):** 25–200 mg daily in single or divided doses. * **Primary Hyperaldosteronism:** 100–400 mg daily for diagnosis or maintenance. * **Hypertension:** 25–100 mg daily. ## Pediatric Dosing * **Heart Failure:** Initial 1–1.5 mg/kg/day once daily or divided BID. Max: 3 mg/kg/day or 50 mg/day (whichever is lower). * **Edema/Hypertension:** 1–3.3 mg/kg/day orally in divided doses (once or twice daily). *Note: Pediatric dosing varies significantly by institution; always consult local pediatric nephrology or cardiology protocols.* ## Dose Adjustments * **Renal Impairment:** Avoid if eGFR <30 mL/min/1.73m² (or SCr >2.5 mg/dL in men/ >2.0 mg/dL in women) due to hyperkalemia risk. * **Hepatic Impairment:** Start at lower end of range; use with caution in severe hepatic disease (risk of fluid/electrolyte imbalance precipitating encephalopathy). ## Contraindications * Hyperkalemia (>5.0 mEq/L at initiation). * Addison’s disease. * Concurrent use of eplerenone, potassium supplements, or strong CYP3A4 inhibitors (if used for certain indications). * Anuria. ## Adverse Effects * **Major:** Hyperkalemia (life-threatening arrhythmias), acute renal failure. * **Common:** Gynecomastia (dose-dependent), breast tenderness, erectile dysfunction, menstrual irregularities, leg cramps, fatigue. ## Key Drug Interactions * **Potassium-elevating agents:** ACE inhibitors, ARBs, NSAIDs, and salt substitutes (high risk of hyperkalemia). * **Lithium:** May decrease renal clearance, increasing risk of lithium toxicity. * **Digoxin:** May interfere with assays or increase serum levels. ## Monitoring * **Potassium:** Baseline, within 1 week of starting/dose increase, monthly for first 3 months, then every 3–6 months. * **Renal Function (SCr/BUN/eGFR):** At the same intervals as potassium. * **Blood Pressure:** Monitor for hypotension. ## Clinical Pearls * **Take with food:** May increase bioavailability and reduce GI upset. * **Switching:** If gynecomastia becomes intolerable, consider switching to eplerenone (which is more selective and lacks progestogenic/androgenic side effects). * **Hyperkalemia management:** If K+ >5.5 mEq/L, hold spironolactone and re-evaluate the medication regimen. *** **Educational Disclaimer:** This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always verify specific dosing, safety, and contraindications by consulting current FDA-approved labeling, local hospital protocols, or clinical decision support software like Lexicomp or Micromedex before prescribing or administering medication.