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# Aldactone (spironolactone)
## Overview
Spironolactone is a potassium-sparing diuretic and a competitive aldosterone receptor antagonist. It acts primarily in the distal convoluted tubule and collecting duct to inhibit sodium reabsorption and potassium excretion.
## Primary Indications
* Heart failure (HFrEF)
* Edema associated with hepatic cirrhosis or nephrotic syndrome
* Primary hyperaldosteronism
* Essential hypertension
* Hirsutism/Acne (off-label)
## Adult Dosing
* **Heart Failure (HFrEF):** Start 12.5–25 mg once daily. Target dose 25–50 mg daily.
* **Edema (Cirrhosis/Nephrotic syndrome):** 100 mg daily; range 25–200 mg daily.
* **Primary Hyperaldosteronism:** 100–400 mg daily prior to surgery; use lowest effective dose for long-term maintenance.
* **Hypertension:** 25–100 mg daily, in single or divided doses.
## Pediatric Dosing
* **Diuretic/Antihypertensive:** 1–3 mg/kg/day orally in 1–2 divided doses. Max: 9 mg/kg/day or 200 mg/day (whichever is less).
* **Heart Failure:** 1–2 mg/kg/day orally in 1–2 divided doses. Max: 2–3.25 mg/kg/day depending on clinical protocol.
## Dose Adjustments
* **Renal Impairment:** Avoid or exercise extreme caution if eGFR <30 mL/min/1.73m². In severe renal failure, the risk of life-threatening hyperkalemia is significant.
* **Hepatic Impairment:** Adjust dose cautiously as altered metabolism may occur.
* **General:** Reduce dose if potassium levels rise above 5.0–5.5 mEq/L.
## Contraindications
* Hyperkalemia (K >5.5 mEq/L)
* Addison’s disease
* Concomitant use of eplerenone
* Anuria
* Acute renal insufficiency or significant renal impairment (CrCl <30 mL/min)
## Adverse Effects
* **Common:** Hyperkalemia, dizziness, fatigue, headache.
* **Endocrine:** Gynecomastia (dose-dependent), breast tenderness, impotence, menstrual irregularities (due to anti-androgen effects).
* **Serious:** Severe hyperkalemia leading to cardiac arrhythmias, agranulocytosis (rare).
## Key Drug Interactions
* **Potassium Supplements/ACE inhibitors/ARBs/NSAIDs:** High risk of severe hyperkalemia.
* **Digoxin:** May increase plasma levels/toxicity; requires monitoring.
* **Lithium:** Spironolactone may reduce renal clearance, increasing lithium toxicity risk.
* **CYP3A4 Inhibitors/Inducers:** May affect spironolactone plasma concentrations.
## Monitoring
* **Serum Potassium:** Check within 1 week of initiation or dose increase, then periodically. If K >5.0 mEq/L, reduce dose or hold.
* **Renal Function:** Serum creatinine and estimated GFR.
* **Blood Pressure:** Monitor for orthostasis, especially when combined with other antihypertensives.
## Clinical Pearls
* Administer consistently with or without food to maintain bioavailability.
* Assess volume status (weight, edema, vitals) regularly.
* Educate patients to avoid potassium-rich diets (e.g., salt substitutes, high intake of bananas/citrus) unless clinically advised.
* If gynecomastia occurs and is intolerable, consider switching to eplerenone (which is more selective and lacks affinity for androgen/progesterone receptors).
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**Educational Disclaimer:** This information is for educational purposes only. Always consult current institutional protocols, updated package inserts, and clinical guidelines (such as ACC/AHA for Heart Failure) prior to prescribing or administering medication.
