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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 renal tubules to inhibit sodium reabsorption and potassium excretion.
## Primary Indications
* Heart failure (NYHA Class II-IV, reduced ejection fraction)
* Edema associated with cirrhosis or nephrotic syndrome
* Primary hyperaldosteronism (Conn's syndrome)
* Essential hypertension (usually as an add-on)
## Adult Dosing
* **Heart Failure:** Initial 12.5–25 mg once daily; target 25 mg daily.
* **Edema/Hypertension:** 25–200 mg daily in divided doses or once daily.
* **Primary Hyperaldosteronism:** 100–400 mg daily in preparation for surgery or for long-term maintenance in patients unfit for surgery.
## Pediatric Dosing
* **Edema/Hypertension:** 1–3.3 mg/kg/day orally in divided doses.
* **Heart Failure (off-label):** 1–2 mg/kg/day once daily; max 25 mg/day.
* *Note: Dosing varies significantly by institutional protocol; calculate based on specific clinical guidelines.*
## Dose Adjustments
* **Renal Impairment:** Avoid if CrCl <30 mL/min or serum creatinine >2.5 mg/dL (men) / >2.0 mg/dL (women). Adjust for hyperkalemia.
* **Hepatic Impairment:** Use caution; fluid and electrolyte balance can be precarious in cirrhosis.
## Contraindications
* Anuria
* Acute renal insufficiency
* Significant impairment of renal excretion
* Hyperkalemia (serum potassium >5.0–5.5 mEq/L)
* Concomitant use of eplerenone or potassium supplements
## Adverse Effects
* **Common:** Hyperkalemia, gynecomastia, breast tenderness, erectile dysfunction, menstrual irregularities.
* **Serious:** Severe hyperkalemia (potential for arrhythmias), metabolic acidosis, hyponatremia.
## Key Drug Interactions
* **Potassium supplements/Salt substitutes:** High risk of lethal hyperkalemia.
* **ACE Inhibitors/ARBs/Renin Inhibitors:** Increased risk of hyperkalemia.
* **Digoxin:** May decrease clearance and interfere with serum assays.
* **NSAIDs:** May reduce efficacy; increased risk of renal impairment/hyperkalemia.
## Monitoring
* **Potassium:** Baseline, within 1 week of starting/dose change, then every 3–6 months.
* **Renal Function (BUN/SCr):** Baseline and periodically.
* **Blood Pressure:** Monitor for hypotension.
## Clinical Pearls
* **Timing:** Administer in the morning to avoid nocturia.
* **Anti-androgen effects:** Gynecomastia is dose-dependent and reversible upon discontinuation.
* **Absorption:** Bioavailability is increased when taken with food.
* **Patient Education:** Instruct patients to avoid excessive intake of potassium-rich foods (e.g., salt substitutes, bananas, spinach) and to recognize signs of hyperkalemia (nausea, muscle weakness, palpitations).
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*Disclaimer: This information is for educational purposes only. Always consult the most current product monograph or institutional prescribing guidelines before administering medication.*
