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# Aldactone (spironolactone)
## Overview
Spironolactone is a potassium-sparing diuretic and aldosterone antagonist. It works by blocking the effects of aldosterone in the kidneys, leading to increased sodium and water excretion while conserving potassium.
## Primary Indications
* Heart failure (NYHA class II-IV) with reduced ejection fraction
* Hypertension (often in combination therapy)
* Primary hyperaldosteronism
* Edema associated with cirrhosis or nephrotic syndrome
## Adult Dosing
* **Heart Failure:** Start at 25 mg once daily. May increase to 50 mg once daily at 4-week intervals as tolerated. Maximum dose is 100 mg once daily.
* **Hypertension:** Start at 25-100 mg once daily. May be given in single or divided doses. Maximum dose is 400 mg once daily.
* **Edema (Cirrhosis, Nephrotic Syndrome):** Start at 100 mg once daily. May adjust between 25 mg and 400 mg per day depending on response.
* **Primary Hyperaldosteronism:** Dosage varies. Short-term pre-operative treatment: 100-400 mg daily in divided doses. Long-term maintenance: 100-400 mg daily in divided doses.
## Pediatric Dosing
* **Hypertension:** 1.5-3 mg/kg/day divided into 2-4 doses. Maximum dose is typically 3 mg/kg/day (up to 100-200 mg/day, depending on age and weight). Local protocols may guide specific dosing.
* **Edema and Congestive Heart Failure:** 1-3 mg/kg/day divided into 2-4 doses. Maximum dose typically 3 mg/kg/day.
## Dose Adjustments
No specific dose adjustments are routinely recommended for hepatic or renal impairment, but close monitoring is crucial due to the risk of hyperkalemia and worsening hepatic encephalopathy. Dose reductions may be necessary based on clinical response and laboratory values.
## Contraindications
* Anuria
* Significant impairment of renal excretory function
* Hyperkalemia
* Addison's disease
* Concomitant use with eplerenone
## Adverse Effects
* **Common:** Hyperkalemia, hyponatremia, fatigue, dizziness, gastrointestinal upset (nausea, vomiting, diarrhea).
* **Less Common/Serious:** Gynecomastia, menstrual irregularities, impotence, hypotension, rash, renal dysfunction.
## Key Drug Interactions
* **ACE inhibitors, Angiotensin II Receptor Blockers (ARBs), Other Potassium-Sparing Diuretics, Potassium Supplements:** Increased risk of severe hyperkalemia. Monitor potassium closely.
* **NSAIDs:** May reduce the diuretic and antihypertensive effect of spironolactone and increase the risk of hyperkalemia.
* **Corticosteroids:** Increased risk of electrolyte disturbances (hypokalemia).
* **Lithium:** Spironolactone may reduce renal clearance of lithium, leading to lithium toxicity.
## Monitoring
* Serum electrolytes (especially potassium and sodium)
* Renal function (serum creatinine, BUN)
* Blood pressure
* Urine output
* Signs and symptoms of hyperkalemia (e.g., muscle weakness, paresthesias, cardiac arrhythmias)
* For gynecomastia or menstrual irregularities
## Clinical Pearls
* Effectiveness for heart failure is often observed within weeks but may require up to 3 months for maximal benefit.
* Administer with food to improve absorption.
* Monitor potassium closely, especially in patients with renal impairment, diabetes, or those taking other medications that increase potassium.
* Due to its anti-androgenic effects, spironolactone can cause gynecomastia in males and menstrual irregularities in females.
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This information is intended for healthcare professionals and does not replace the need to consult the most current prescribing information and clinical guidelines.
