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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 inhibit sodium reabsorption and potassium excretion.
## Primary Indications
* Heart failure (HFrEF)
* Edema associated with hepatic cirrhosis or nephrotic syndrome
* Primary hyperaldosteronism (Conn’s syndrome)
* Essential hypertension
* Off-label: Acne vulgaris, hirsutism (anti-androgen effects)
## 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 in preparation for surgery or long-term management.
* **Hypertension:** 25–100 mg daily in single or divided doses.
## Pediatric Dosing
* **Diuretic/Antihypertensive:** 1–3.3 mg/kg/day orally in divided doses (Max: 200 mg/day).
* **Heart Failure:** 1–2 mg/kg/day daily or in divided doses (Max: 25 mg/day).
* *Note: Always verify weight-based dosing against current institutional protocols.*
## Dose Adjustments
* **Renal Impairment:** Avoid or use extreme caution if eGFR <30 mL/min/1.73m² due to high risk of hyperkalemia. Reduce dose or extend dosing interval in patients with moderate impairment.
* **Hepatic Impairment:** Generally well-tolerated, but monitor closely as fluid/electrolyte shifts can precipitate hepatic encephalopathy.
## Contraindications
* Hypersensitivity to spironolactone
* Anuria
* Acute renal insufficiency or significant renal impairment
* Addison’s disease
* Hyperkalemia (serum K+ >5.0 mEq/L)
* Concomitant use of eplerenone
## Adverse Effects
* **Common:** Hyperkalemia, dizziness, fatigue.
* **Endocrine:** Gynecomastia (dose-dependent), breast tenderness, menstrual irregularities, erectile dysfunction.
* **Serious:** Severe hyperkalemia (cardiac arrhythmias), hyponatremia, metabolic acidosis, agranulocytosis.
## Key Drug Interactions
* **Potassium Supplements/Salt Substitutes:** High risk of severe hyperkalemia.
* **ACE Inhibitors / ARBs / Renin Inhibitors:** Synergistic risk of hyperkalemia.
* **NSAIDs:** May reduce diuretic efficacy and increase risk of renal impairment/hyperkalemia.
* **Digoxin:** May increase plasma digoxin concentrations.
* **Lithium:** May reduce renal clearance and increase lithium toxicity risk.
## Monitoring
* **Potassium:** Baseline, within 1 week of initiation/dose increase, and at least monthly for the first 3 months.
* **Renal Function (SCr/BUN):** Baseline and monitor routinely.
* **Blood Pressure:** Monitor for hypotension.
* **Signs of Hyperkalemia:** Palpitations, muscle weakness.
## Clinical Pearls
* **Administer consistently:** Take with or without food, but be consistent to minimize variability in absorption. Taking with food may improve bioavailability.
* **Anti-androgen profile:** Due to its structure, it blocks androgen receptors; monitor patients for breast-related side effects.
* **Delayed onset:** Diuretic effects may take up to 3 days to manifest; maximum effect on blood pressure may not be seen for 2–4 weeks.
* **Hyperkalemia risk:** Use with extreme caution in patients with diabetes or those on multiple agents that affect the RAAS system.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical practice protocols vary by institution. Always verify dosages, contraindications, and drug interactions against the most current prescribing information (package insert) and clinical decision support tools before prescribing or administering medication.
