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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 retaining potassium.
## Primary Indications
* Heart failure (NYHA class II-IV) with reduced ejection fraction
* Edema associated with cirrhosis and nephrotic syndrome
* Essential hypertension
* Primary hyperaldosteronism
## Adult Dosing
* **Heart Failure:** Starting dose 25 mg orally once daily. May increase to 50 mg orally once daily at 4-week intervals as tolerated. Maximum dose 100 mg orally once daily.
* **Edema (Cirrhosis/Nephrotic Syndrome):** Starting dose 100 mg orally once daily. May adjust between 25-200 mg orally per day in single or divided doses.
* **Hypertension:** Starting dose 25-100 mg orally once daily, may be combined with other antihypertensives. Maximum dose typically 400 mg orally per day, though lower doses are often sufficient.
* **Primary Hyperaldosteronism (Preoperative or Long-Term Medical Treatment):** 100-400 mg orally per day in divided doses.
*Note: Dosing for heart failure and hypertension may be guided by local protocol.*
## Pediatric Dosing
Dosing in pediatric patients is not well established and should be individualized based on clinical response and monitoring. Suggested starting doses include:
* **General:** 1.5-3 mg/kg/day orally in 2-4 divided doses.
* **Edema (Cirrhosis):** 1.5-3 mg/kg/day orally, may increase up to 3.3 mg/kg/day.
* **Hypertension:** 1-2 mg/kg/day orally as a single dose or divided.
*Note: Pediatric dosing requires careful titration and monitoring by a qualified clinician.*
## Dose Adjustments
* **Renal Impairment:** Use with caution. Monitor potassium closely. Dose adjustments may be necessary, especially in moderate to severe renal impairment.
* **Hepatic Impairment:** Use with caution due to potential for hepatic encephalopathy. Dose adjustments may be necessary.
## Contraindications
* Anuria
* Acute renal insufficiency
* Significant impairment of renal excretory function
* Hyperkalemia (serum potassium >5.5 mEq/L)
* Addison's disease
* Known hypersensitivity to spironolactone or its components
## Adverse Effects
* **Common:** Hyperkalemia, hyponatremia, gynecomastia (men), menstrual irregularities (women), fatigue, headache, nausea, vomiting, diarrhea, abdominal pain, rash.
* **Serious:** Severe hyperkalemia, Stevens-Johnson syndrome, toxic epidermal necrolysis, hepatic failure, renal dysfunction, interstitial nephritis.
## Key Drug Interactions
* **ACE inhibitors/ARBs:** Increased risk of hyperkalemia.
* **Potassium supplements/Potassium-containing salt substitutes:** Increased risk of hyperkalemia.
* **NSAIDs:** May reduce diuretic and antihypertensive effects, and increase risk of hyperkalemia.
* **Corticosteroids:** May increase potassium loss.
* **Digoxin:** Spironolactone may increase digoxin levels.
* **Lithium:** Spironolactone may reduce lithium clearance.
## Monitoring
* **Serum potassium:** Monitor frequently, especially during initiation, dose increases, and in patients with renal impairment or concomitant use of other potassium-raising agents.
* **Renal function (serum creatinine, BUN):** Monitor periodically.
* **Electrolytes (sodium):** Monitor periodically.
* **Blood pressure:** Monitor regularly.
* **Signs and symptoms of hyperkalemia:** Muscle weakness, fatigue, paresthesias, cardiac arrhythmias.
* **Women:** Menstrual irregularities, breast tenderness.
* **Men:** Gynecomastia, breast tenderness.
## Clinical Pearls
* Dose for heart failure is typically initiated at 25 mg once daily and may be titrated to 50 mg once daily if tolerated, with a maximum of 100 mg once daily.
* Hyperkalemia is the most significant adverse effect; monitor potassium closely, especially in patients with renal impairment or those taking other drugs that can increase potassium.
* Due to its anti-androgenic effects, gynecomastia and menstrual irregularities can occur.
* Consider co-administration with a thiazide diuretic in some cases to mitigate potassium retention, but monitor for hypokalemia.
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*Disclaimer: This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant guidelines before making clinical decisions.*
