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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 duct, promoting sodium and water excretion while retaining potassium.
## Primary Indications
* Heart failure (HFrEF, NYHA Class II–IV)
* Edema associated with cirrhosis, nephrotic syndrome, or hypertension
* Primary hyperaldosteronism (Conn’s syndrome)
* Hirsutism/Acne (off-label)
## Adult Dosing
* **Heart Failure:** Initial 12.5–25 mg once daily. Target dose: 25–50 mg daily.
* **Edema (Cirrhosis/Nephrotic Syndrome/Ascites):** 25–200 mg daily in single or divided doses.
* **Hypertension:** 25–100 mg daily.
* **Primary Hyperaldosteronism:** 100–400 mg daily prior to surgery; maintenance dosing varies based on clinical response.
## Pediatric Dosing
* **Heart Failure:** Initial 1 mg/kg/day once daily or divided BID. Max: 2–3 mg/kg/day or 50 mg/day.
* **Edema/Hypertension:** 1–3.3 mg/kg/day in divided doses. Max: 100 mg/day.
* *Note: Pediatric dosing should be verified against institutional protocols (e.g., Harriet Lane Handbook) as these vary significantly by age and weight.*
## Dose Adjustments
* **Renal Impairment:** Avoid if CrCl < 30 mL/min due to high risk of hyperkalemia.
* **Hepatic Impairment:** Dose reduction may be necessary in patients with severe cirrhosis.
## Contraindications
* Anuria
* Acute renal insufficiency
* Significant impairment of renal excretory function (CrCl < 30 mL/min)
* Hyperkalemia (K > 5.0 mEq/L at baseline)
* Addison’s disease
* Concomitant use of eplerenone or potassium supplements
## Adverse Effects
* **Common:** Hyperkalemia, gynecomastia, breast tenderness, abdominal pain, diarrhea.
* **Serious:** Severe hyperkalemia (cardiac arrhythmias), metabolic acidosis, hypovolemia/dehydration, rare cases of agranulocytosis.
## Key Drug Interactions
* **ACE Inhibitors/ARBs/Direct Renin Inhibitors:** Increases risk of severe hyperkalemia.
* **Potassium Supplements/Salt Substitutes:** Contraindicated; high risk of fatal hyperkalemia.
* **NSAIDs:** May reduce diuretic efficacy and increase risk of acute kidney injury and hyperkalemia.
* **Digoxin:** May interfere with radioimmunoassay measurements and increase digoxin toxicity.
* **Lithium:** May reduce renal clearance of lithium, increasing toxicity risk.
## Monitoring
* **Potassium:** Within 1 week of initiation or dose change, then monthly for 3 months, then every 3 months.
* **Renal Function (SCr/BUN):** Baseline and ongoing monitoring; monitor closely in patients with existing CKD.
* **Blood Pressure:** Monitor for orthostasis and hypotension.
## Clinical Pearls
* **Gynecomastia:** Dose-related and often reversible upon discontinuation.
* **Potassium Thresholds:** If K > 5.5 mEq/L, withhold dose immediately.
* **Evidence-Based Heart Failure:** Spironolactone is a mortality-reducing agent in HFrEF; titration is essential to achieve the target dose of 50 mg daily as tolerated.
* **Administration:** Take consistently with or without food to minimize GI upset, but choose one method and stick to it to maintain steady drug levels.
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**Educational Disclaimer:** This information is for educational purposes only and does not constitute medical advice. Clinical protocols vary; always consult current institutional guidelines, electronic health record prescribing alerts, and the most recent FDA-approved package insert before prescribing or administering medication.
