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# Spironolactone (Aldactone)
## Overview
Spironolactone is a potassium-sparing diuretic and a competitive aldosterone antagonist. It is a mineralocorticoid receptor antagonist.
## Primary Indications
* Heart failure (NYHA class II-IV) to reduce hospitalizations
* Hypertension, particularly resistant hypertension
* Primary aldosteronism
* Edema associated with liver cirrhosis or nephrotic syndrome
* Hirsutism in women
## Adult Dosing
* **Heart Failure:** Start at 25 mg once daily. May increase to 50 mg once daily after 4 weeks as tolerated, or titrate to a target dose of 100 mg once daily.
* **Hypertension:** 25-100 mg once daily. Higher doses may be required but are typically reserved for resistant cases.
* **Primary Aldosteronism (pre-operative):** 100-400 mg daily, divided.
* **Edema (Cirrhosis/Nephrotic Syndrome):** 25-100 mg once daily. May be increased if needed.
* **Hirsutism:** 100-200 mg once daily.
## Pediatric Dosing
* **Edema/Hypertension:** 1.5-3 mg/kg/day divided into 2-4 doses. Maximum: 100 mg/day. Dosing should be individualized.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Avoid if serum creatinine > 2.5 mg/dL or if creatinine clearance < 30 mL/min.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary.
## Contraindications
* Anuria
* Acute renal insufficiency
* Significant impairment of renal excretory function
* Hyperkalemia
* Addison's disease
* Concomitant use of eplerenone
## Adverse Effects
* Hyperkalemia (most significant; especially in patients with renal impairment or those taking ACE inhibitors, ARBs, or potassium supplements)
* Gynecomastia, menstrual irregularities, breast tenderness (due to anti-androgenic effects)
* Erectile dysfunction, decreased libido
* Gastrointestinal upset (nausea, vomiting, diarrhea)
* Dizziness, fatigue
* Hyponatremia
* Dehydration
## Key Drug Interactions
* **Potassium Supplements, ACE Inhibitors, ARBs, NSAIDs, Heparin, Trimethoprim:** Increased risk of hyperkalemia.
* **Other Diuretics:** Increased risk of dehydration and hyponatremia.
* **Lithium:** Spironolactone may decrease lithium clearance, leading to lithium toxicity.
* **Digoxin:** Spironolactone may increase digoxin levels.
* **Choline Magnesium Trisalicylate:** May reduce the diuretic and antihypertensive effect of spironolactone.
## Monitoring
* Serum potassium levels (frequently initially, then periodically)
* Renal function (serum creatinine, BUN)
* Electrolytes (sodium)
* Blood pressure
## Clinical Pearls
* Administer with food to increase absorption.
* Monitor for signs and symptoms of hyperkalemia.
* Anticipate and counsel patients on potential endocrine side effects (gynecomastia, menstrual irregularities).
* Obtain baseline and periodic electrolyte and renal function tests.
* Discontinue or reduce dose if serum potassium exceeds 5.5 mEq/L or serum creatinine rises significantly.
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*This information is intended as a quick reference and does not replace a comprehensive review of the drug's prescribing information and current clinical guidelines. Always verify current prescribing information and consult relevant resources before making clinical decisions.*
