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# Aldactone (Spironolactone)
## Overview
Spironolactone is a potassium-sparing diuretic that acts as a competitive antagonist of aldosterone at the distal renal tubule. It promotes sodium and water excretion while retaining potassium.
## Primary Indications
* Heart failure (HFrEF)
* Edema associated with cirrhosis or nephrotic syndrome
* Primary hyperaldosteronism (Conn’s syndrome)
* Essential hypertension
* Off-label: Acne vulgaris, hirsutism, gender-affirming hormone therapy
## Adult Dosing
* **HFrEF:** Initially 12.5–25 mg daily; titrate to target of 50 mg daily as tolerated.
* **Edema (Cirrhosis/Nephrotic Syndrome):** 100 mg daily; range 25–200 mg daily.
* **Primary Hyperaldosteronism:** 100–400 mg daily before surgery; lower doses for long-term maintenance.
* **Hypertension:** 25–100 mg daily in one or two divided doses.
## Pediatric Dosing
* **Edema/Hypertension:** 1–3.3 mg/kg/day divided every 6–24 hours. Maximum: 200 mg/day.
* **HFrEF:** Initially 1 mg/kg/day once daily; titrate to maximum 2 mg/kg/day (not to exceed 25 mg/day).
## Dose Adjustments
* **Renal Impairment:** Avoid if eGFR <30 mL/min/1.73m² or if serum creatinine >2.5 mg/dL (men) or >2.0 mg/dL (women) due to high risk of severe hyperkalemia.
* **Hepatic Impairment:** No specific adjustment, but use caution with ascites to avoid electrolyte shifts and hepatic encephalopathy.
## Contraindications
* Anuria
* Acute renal insufficiency
* Significant renal impairment (as defined above)
* Hyperkalemia (K+ >5.0 mEq/L)
* Concomitant use of eplerenone or potassium supplements
## Adverse Effects
* **Common:** Hyperkalemia, dizziness, fatigue.
* **Endocrine (due to anti-androgen activity):** Gynecomastia, breast tenderness, menstrual irregularities, erectile dysfunction.
* **Serious:** Severe hyperkalemia leading to arrhythmias, dehydration, hyponatremia.
## Key Drug Interactions
* **Potassium-elevating agents:** ACE inhibitors, ARBs, NSAIDs, and potassium supplements drastically increase hyperkalemia risk.
* **Digoxin:** May increase serum digoxin levels; monitor closely.
* **Lithium:** May decrease lithium clearance, increasing toxicity risk.
## Monitoring
* **Potassium/Creatinine:** Baseline, 1 week after initiation/titration, and monthly for the first 3 months.
* **Blood Pressure:** Monitor periodically.
* **Physical Exam:** Assess for signs of fluid overload or dehydration.
## Clinical Pearls
* **Potassium Threshold:** Withhold or reduce dose if K+ >5.0 mEq/L.
* **Timing:** Administer in the morning to avoid nocturia.
* **Tablet Splitting:** Scored tablets may be split to achieve specific doses.
* **Eplerenone:** If a patient experiences significant hormonal side effects (gynecomastia), consider switching to eplerenone, which is more selective and lacks active anti-androgen properties.
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**Educational Disclaimer:** This summary is for informational purposes only and does not constitute medical advice. Dosing protocols may vary by institution or clinical context. Always consult the current manufacturer's prescribing information, institutional guidelines, and clinical software before prescribing or administering any medication.
