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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 convoluted tubule and collecting ducts to inhibit sodium reabsorption and potassium excretion. ## Primary Indications * Heart failure (NYHA Class II–IV) with reduced ejection fraction. * Edema associated with cirrhosis, nephrotic syndrome, or congestive heart failure. * Primary hyperaldosteronism (diagnosis and long-term management). * Essential hypertension (often as add-on therapy). ## Adult Dosing * **Heart Failure:** Initial 12.5–25 mg once daily; titrate to 25 mg daily based on patient tolerance and serum potassium. * **Edema:** 25–200 mg daily in single or divided doses. * **Primary Hyperaldosteronism:** 100–400 mg daily (pre-operative). * **Hypertension:** 25–100 mg daily. ## Pediatric Dosing * **Edema/Hypertension:** 1–3.3 mg/kg/day orally in 1–2 divided doses. Max: 200 mg/day (or equivalent to adult dosing). * **Heart Failure (OFF-LABEL):** 1–2 mg/kg/day once daily. Max: 25 mg/day. * *Note: Practice varies by institution; consult local pediatric formulary or institutional protocol.* ## Dose Adjustments * **Renal Impairment:** Avoid if eGFR <30 mL/min/1.73m² (increased risk of hyperkalemia). * **Hepatic Impairment:** Use caution; dosage adjustment may be necessary due to extensive hepatic metabolism. ## Contraindications * Hyperkalemia (serum potassium >5.0 mEq/L). * Addison’s disease. * Concomitant use of eplerenone. * Anuria. * Acute renal insufficiency or significant renal impairment (eGFR <30 mL/min/1.73m²). ## Adverse Effects * **Common:** Hyperkalemia, dizziness, fatigue, headache. * **Endocrine:** Gynecomastia (dose-dependent), breast tenderness, menstrual irregularities, erectile dysfunction. * **Serious:** Severe hyperkalemia (cardiac arrhythmias), hyponatremia, metabolic acidosis. ## Key Drug Interactions * **Potassium Supplements/Potassium-Sparing Diuretics:** Significant risk of life-threatening hyperkalemia. * **ACE Inhibitors / ARBs / Renin Inhibitors:** Increased risk of hyperkalemia. * **NSAIDs:** May reduce diuretic efficacy and increase risk of renal impairment/hyperkalemia. * **Digoxin:** May increase plasma digoxin concentrations (falsely elevated serum levels or altered renal clearance). * **Lithium:** May reduce renal clearance of lithium, increasing toxicity risk. ## Monitoring * **Serum Potassium:** Before initiation, at week 1, week 4, and every 3–6 months thereafter (more frequent if dose is adjusted or renal function changes). * **Renal Function (SCr/eGFR):** Baseline and periodic monitoring. * **Blood Pressure:** Monitor for orthostasis and therapeutic effect. ## Clinical Pearls * **Timing:** Administer with or without food, but be consistent to minimize variability in absorption. * **Side Effect Management:** If gynecomastia occurs, consider switching to eplerenone (a more selective aldosterone antagonist) if the patient's insurance/clinical status allows. * **Hyperkalemia Risk:** Advise patients to avoid salt substitutes containing potassium (e.g., potassium chloride) and minimize high-potassium food intake. *** *Disclaimer: This information is for educational purposes only. Dosing, contraindications, and drug interactions are subject to change. Always verify current prescribing information in standard references such as Lexicomp or Micromedex, and consult institutional protocols before clinical implementation.*