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# Aldactone (Spironolactone) ## Overview Spironolactone is a potassium-sparing diuretic and aldosterone antagonist. It acts primarily in the distal convoluted tubule and collecting duct, competitively inhibiting aldosterone receptors. ## Primary Indications * Heart Failure (HFrEF) * Edema associated with cirrhosis or nephrotic syndrome * Primary hyperaldosteronism (Conn's syndrome) * Essential hypertension (typically as an add-on agent) * Treatment of hirsutism/acne (off-label) ## Adult Dosing * **Heart Failure (HFrEF):** Initial 12.5–25 mg daily; optimize to 25–50 mg daily as tolerated. * **Edema (Cirrhosis/Nephrotic Syndrome):** 25–200 mg daily in single or divided doses. * **Primary Hyperaldosteronism:** 100–400 mg daily prior to surgery; for long-term maintenance, use the lowest effective dose. * **Hypertension:** 25–100 mg daily in single or divided doses. ## Pediatric Dosing * **Diuretic/Antihypertensive:** 1–3 mg/kg/day divided every 12–24 hours (up to 200 mg/day). Dosing often requires titration based on institutional guidelines. ## Dose Adjustments * **Renal Impairment:** Not recommended if eGFR <30 mL/min/1.73m² due to high risk of hyperkalemia. * **Hepatic Impairment:** No specific adjustment, but monitor closely for fluid/electrolyte shifts. ## Contraindications * Hyperkalemia (K > 5.0 mEq/L at initiation). * Addison’s disease. * Concomitant use of eplerenone. * Anuria or acute renal failure. ## Adverse Effects * **Common:** Hyperkalemia, hyponatremia, dizziness, headache. * **Endocrine:** Gynecomastia, breast tenderness, menstrual irregularities, erectile dysfunction (secondary to weak anti-androgen activity). * **Serious:** Severe hyperkalemia leading to arrhythmias, GI upset/bleeding, acute kidney injury. ## Key Drug Interactions * **Potassium Supplements/Potassium-sparing Diuretics:** High risk of lethal hyperkalemia. * **ACE Inhibitors/ARBs/Renin Inhibitors:** Synergistic risk of hyperkalemia. * **NSAIDs:** May reduce diuretic efficacy and increase risk of renal impairment and hyperkalemia. * **Lithium:** Spironolactone may reduce lithium renal clearance, increasing risk of toxicity. * **Digoxin:** May interfere with assays and increase digoxin serum levels. ## Monitoring * **Potassium:** Baseline, within 1 week of initiation or dose change, then monthly for 3 months, then every 3–6 months. * **Renal Function (BUN/SCr):** Baseline and monitor per potassium schedule. * **Blood Pressure:** Monitor for orthostasis, especially at initiation. * **Clinical:** Watch for signs of hyperkalemia (muscle weakness, palpitations, arrhythmias). ## Clinical Pearls * **Hyperkalemia Risk:** Advise patients to avoid salt substitutes containing potassium chloride. * **Bioavailability:** Food increases the absorption of spironolactone. Consistency in administration relative to meals is recommended. * **Potassium Thresholds:** In HFrEF, hold if K > 5.5 mEq/L. * **Eplerenone Alternative:** Consider eplerenone if the patient experiences intolerable anti-androgen side effects (e.g., gynecomastia) while on spironolactone. *** **Educational Disclaimer:** This information is for educational purposes only. Clinical practice guidelines vary by institution and patient-specific factors. Always verify prescribing information against current reference sources (e.g., Lexicomp, UpToDate) and local hospital protocols before administration.