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# Aldactone (spironolactone)
## Overview
Spironolactone is a potassium-sparing diuretic and a competitive aldosterone antagonist.
## Primary Indications
* Heart failure (NYHA class II-IV) with reduced ejection fraction
* Edema associated with cirrhosis or nephrotic syndrome
* Essential hypertension (often as adjunctive therapy)
* Primary hyperaldosteronism (diagnostic and therapeutic)
* Hirsutism in women
## Adult Dosing
* **Heart Failure:** 25 mg orally once daily. May titrate up to 50 mg once daily or 100 mg once daily based on response and tolerability, aiming for a serum potassium of $\le$ 5.0 mEq/L. Max dose: 100 mg daily.
* **Cirrhosis with Edema:** 25-100 mg orally once daily. Max dose: 400 mg daily.
* **Nephrotic Syndrome:** 100-200 mg orally once daily. Max dose: 400 mg daily.
* **Hypertension:** 25-100 mg orally once daily. Max dose: 200 mg daily.
* **Primary Hyperaldosteronism:** 100-400 mg orally once daily.
* **Hirsutism:** 50-200 mg orally once daily.
Dosing is typically initiated at the lowest effective dose and titrated upwards as needed and tolerated.
## Pediatric Dosing
* **Edema/Ascites/Hypertension:** 1-3 mg/kg/day orally divided into 1-2 doses. Max dose: 100 mg daily. Dosing can be adjusted based on clinical response and serum potassium.
## Dose Adjustments
* **Renal Impairment:** Use with caution in patients with renal impairment. Dose adjustments may be necessary, especially in conjunction with other medications affecting potassium levels. Monitor potassium closely.
* **Hepatic Impairment:** Use with caution in patients with hepatic impairment.
## Contraindications
* Addison's disease
* Hyperkalemia (serum potassium > 5.5 mEq/L)
* Anuria or acute renal failure
* Concomitant use of eplerenone
## Adverse Effects
Common: Hyperkalemia, hyponatremia, dizziness, headache, fatigue, gastrointestinal upset (nausea, vomiting, diarrhea), gynecomastia (men), menstrual irregularities (women), rash.
Less common: Hypoalbuminemia, confusion, hyperchloremic metabolic acidosis, sexual dysfunction.
## Key Drug Interactions
* **ACE inhibitors, ARBs, NSAIDs, potassium supplements, heparin, trimethoprim:** Increased risk of hyperkalemia.
* **Other diuretics:** Additive diuretic effect, increased risk of electrolyte imbalances.
* **Corticosteroids:** May increase risk of hyponatremia.
* **Digoxin:** Spironolactone may increase digoxin levels, increasing risk of toxicity.
* **Lithium:** Spironolactone may decrease lithium clearance, increasing lithium toxicity risk.
* **Norepinephrine:** Spironolactone may reduce the vascular responsiveness to norepinephrine.
## Monitoring
* **Serum electrolytes:** Especially potassium and sodium, at baseline and periodically during treatment. More frequent monitoring is crucial following dose increases or in patients with risk factors for hyperkalemia or hyponatremia.
* **Renal function:** BUN and creatinine at baseline and periodically.
* **Blood pressure:** Regularly, especially when used for hypertension or heart failure.
* **For hirsutism:** Monitor for clinical improvement and adverse effects.
## Clinical Pearls
* Administer with food to enhance absorption and reduce gastrointestinal upset.
* Hyperkalemia is a significant risk; counsel patients on avoiding potassium-rich foods and supplements, and to report symptoms of hyperkalemia (muscle weakness, fatigue, paresthesias).
* Gynecomastia in men is common and often dose-related, but can be irreversible.
* Effect on blood pressure may be delayed and takes weeks to become fully apparent.
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*This information is intended for clinical use and does not replace a thorough review of the official prescribing information (package insert) for Aldactone (spironolactone). Always consult the most current drug monograph for complete and up-to-date details.*
