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# Spironolactone (Aldactone)
## Overview
Spironolactone is a potassium-sparing diuretic and aldosterone antagonist. It works by blocking the action of aldosterone, a hormone that causes the body to retain sodium and water, thereby increasing urine output and decreasing blood pressure.
## Primary Indications
* Heart Failure (reduced ejection fraction)
* Hypertension
* Edema (associated with cirrhosis, nephrotic syndrome, or congestive heart failure)
* Primary Aldosteronism
* Hirsutism (off-label)
## Adult Dosing
* **Heart Failure:** Initiate at 12.5-25 mg orally once daily. Titrate up to 25-50 mg orally once daily as tolerated. Maximum dose is typically 100 mg orally once daily.
* **Hypertension:** Initiate at 25-100 mg orally once daily in one or two divided doses. May increase gradually. Maximum dose is typically 200 mg orally once daily.
* **Edema (Cirrhosis, CHF, Nephrotic Syndrome):** Initiate at 25-100 mg orally once daily in one or two divided doses. May increase gradually. Maximum dose is typically 200 mg orally once daily.
* **Primary Aldosteronism:** Preoperative: 100-400 mg orally once daily in two to four divided doses. Long-term management: Dose individualized based on patient response, typically 25-100 mg orally once daily.
## Pediatric Dosing
Dosing in pediatric patients is highly variable and depends on the indication and patient weight. Specific protocols or expert consultation are often required.
* **Edema/Hypertension:** Commonly initiated at 1-3 mg/kg/day orally divided into two to four doses. Maximum daily dose is generally 100 mg.
* **Hirsutism:** Commonly initiated at 1-2 mg/kg/day orally divided into two doses, not to exceed 200 mg/day.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Significant impairment may necessitate dose reduction or discontinuation. Monitor potassium closely.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary.
## Contraindications
* Anuria
* Acute renal insufficiency
* Significant and progressive renal impairment
* Hyperkalemia (serum potassium >5.5 mEq/L)
* Addison's disease
* Known hypersensitivity to spironolactone or its components
## Adverse Effects
* **Common:** Hyperkalemia, hyponatremia, dizziness, headache, fatigue, gastrointestinal upset (nausea, vomiting, diarrhea), gynecomastia (males), menstrual irregularities (females), hirsutism (females), deepening of the voice.
* **Serious:** Severe hyperkalemia, Stevens-Johnson syndrome, toxic epidermal necrolysis, dehydration, interstitial nephritis.
## Key Drug Interactions
* **ACE Inhibitors, ARBs, NSAIDs, Potassium Supplements, Salt Substitutes:** Increased risk of hyperkalemia.
* **Diuretics (other than potassium-sparing):** Increased risk of dehydration and hyponatremia.
* **Lithium:** Spironolactone can decrease renal clearance of lithium, leading to toxic levels.
* **Digoxin:** Spironolactone can increase digoxin levels, increasing the risk of toxicity.
* **Corticosteroids:** May blunt the diuretic and natriuretic effect of spironolactone.
## Monitoring
* **Serum Potassium:** Essential, especially with concomitant use of ACE inhibitors, ARBs, NSAIDs, or renal impairment.
* **Serum Sodium:** Monitor for hyponatremia.
* **Renal Function (BUN, Creatinine):** Monitor periodically, especially in patients with pre-existing renal disease or those at risk.
* **Blood Pressure:** Monitor for efficacy and hypotension.
* **Fluid Status:** Monitor for signs of dehydration or fluid overload.
* **Gynecologic Symptoms:** Monitor for breast tenderness, gynecomastia, menstrual irregularities.
## Clinical Pearls
* Administer with food to enhance absorption and minimize gastrointestinal upset.
* Due to its hormonal effects, gynecomastia and menstrual irregularities are relatively common.
* Onset of diuresis may be delayed compared to loop or thiazide diuretics.
* Titration of dose should be gradual, especially in heart failure, to minimize adverse effects and allow for adaptation.
* Concurrent use with other potassium-sparing agents is generally contraindicated due to severe hyperkalemia risk.
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**Disclaimer:** This information is intended for healthcare professionals. Please consult the most current prescribing information and institutional protocols for definitive guidance.
