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# Aldactone (spironolactone)
## Overview
Potassium-sparing diuretic and aldosterone receptor antagonist. Also used as an antiandrogen. Onset of diuresis: 2–3 days; full effect may take 2 weeks.
## Primary Indications
- Heart failure with reduced ejection fraction (HFrEF)
- Resistant hypertension (as add-on)
- Primary hyperaldosteronism (diagnosis and management)
- Cirrhosis with ascites (with loop diuretic)
- Acne vulgaris, hirsutism, female pattern hair loss (off-label; antiandrogen effects)
## Adult Dosing
- **HFrEF:** Initiate 12.5–25 mg once daily; target 25 mg once daily; max 50 mg/day.
- **Resistant hypertension:** 25–50 mg once daily; max 100 mg/day.
- **Primary hyperaldosteronism:** 100–400 mg/day in divided doses; adjust based on response/potassium.
- **Cirrhosis with ascites:** 100 mg once daily; max 400 mg/day (often with furosemide).
- **Acne/hirsutism (off-label):** 50–200 mg/day in divided doses; typical 50–100 mg/day.
## Pediatric Dosing
- **Diuretic/hypertension:** 1–3 mg/kg/day divided q12–24h; max 100 mg/day.
- **Heart failure (limited data):** 0.5–1.5 mg/kg once daily; max 50 mg/day.
- **Ascites in cirrhosis:** 1–3 mg/kg/day (max 100 mg/day).
*Exact dosing per local protocol; monitor potassium and renal function.*
## Dose Adjustments
- **Renal impairment:** Avoid if CrCl <30 mL/min; use with caution (risk of hyperkalemia).
- **Hepatic impairment:** No specific adjustment; monitor electrolytes.
- **Elderly:** Start at lower end of dosing range.
## Contraindications
- Anuria, acute renal failure, severe renal impairment (CrCl <30 mL/min)
- Hyperkalemia (potassium >5.0 mEq/L)
- Addison’s disease
- Concomitant use with eplerenone or other potassium-sparing diuretics
- Pregnancy (antiandrogen effects; avoid unless essential)
## Adverse Effects
- **Common:** Hyperkalemia, gynecomastia (dose-related), menstrual irregularities, breast tenderness, headache, GI upset.
- **Serious:** Severe hyperkalemia (cardiac arrhythmias), acute kidney injury, hyponatremia.
- **Other:** Metabolic acidosis, decreased libido, impotence.
## Key Drug Interactions
- **ACE inhibitors, ARBs, direct renin inhibitors:** ↑ risk of hyperkalemia.
- **Potassium supplements, salt substitutes:** ↑ risk of hyperkalemia.
- **NSAIDs:** ↓ diuretic effect, ↑ risk of renal impairment and hyperkalemia.
- **Digoxin:** May increase digoxin levels (monitor).
- **Lithium:** ↑ lithium toxicity risk.
- **CYP3A4 inhibitors (e.g., ketoconazole):** May increase spironolactone exposure.
## Monitoring
- Serum potassium, creatinine, BUN at baseline, 1–2 weeks after initiation, then periodically.
- Blood pressure, urine output, signs of hyperkalemia (weakness, paresthesias, ECG changes).
- In HFrEF: Monitor renal function and potassium with each dose adjustment.
- In cirrhosis: Monitor electrolytes and renal function often.
## Clinical Pearls
- Take with food to minimize GI upset.
- Gynecomastia is dose-dependent and reversible upon discontinuation; may persist for months.
- For resistant hypertension, check potassium and renal function 2 weeks after starting.
- In HFrEF, use with loop diuretic if needed; hypokalemia from loop diuretic may offset hyperkalemia risk.
- Consider amiloride if gynecomastia is intolerable (but weaker antiandrogen effect).
- Spironolactone’s active metabolites have long half-lives (up to 16 hours); once-daily dosing is usually sufficient.
*Educational disclaimer: This information is for educational purposes only and does not replace clinical judgment. Always verify current prescribing information from the manufacturer’s label and local guidelines before initiating therapy.*
