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# Aldactone (spironolactone)
## Overview
Potassium-sparing diuretic and aldosterone antagonist. Used for its diuretic and antihypertensive effects, as well as mineralocorticoid receptor blockade. Onset of action is slow (2–3 days). Long half-life with active metabolites.
## Primary Indications
- Heart failure with reduced ejection fraction (HFrEF)
- Resistant hypertension
- Edema/cirrhotic ascites (often with loop diuretic)
- Primary hyperaldosteronism (diagnosis and long-term management)
- Acne vulgaris and hirsutism (off-label, common)
## Adult Dosing
- **Heart failure (HFrEF):** Initiate 12.5–25 mg once daily; target 25–50 mg once daily. Max 50 mg/day.
- **Hypertension:** 25–50 mg once daily; max 100 mg/day. Divide BID if needed.
- **Edema/ascites:** 100–400 mg/day in 1–2 divided doses; max 400 mg/day.
- **Primary hyperaldosteronism:** 100–400 mg/day; titrate to lowest effective dose.
- **Acne/hirsutism:** 25–200 mg/day in divided doses (off-label).
## Pediatric Dosing
- **Diuretic/antihypertensive:** 1–3 mg/kg/day in 2–4 divided doses; max 4 mg/kg/day (not to exceed adult max). Exact dosing depends on local protocol and indication. For neonates, use with caution; limited data.
- **Heart failure:** Data limited; typical range 1–3 mg/kg/day divided BID; max 100 mg/day. Follow institutional guidelines.
- *Note:* Many pediatric dosing regimens are based on clinical response and serum potassium; consult local pediatric formulary.
## Dose Adjustments
- **Renal impairment:** Avoid if eGFR <30 mL/min/1.73m² (increased risk of hyperkalemia). For mild-moderate impairment, start lower and monitor K+ closely.
- **Hepatic impairment:** Caution in severe liver disease; no specific dose reduction, but monitor for electrolyte imbalance.
- **Elderly:** Start at low end of dose range, titrate slowly.
## Contraindications
- Hyperkalemia (K+ >5.0 mEq/L; local protocols may define threshold)
- Anuria, acute/chronic renal failure with oliguria
- Addison’s disease
- Concomitant use of eplerenone
## Adverse Effects
- **Hyperkalemia** (most serious; dose-related, especially with renal impairment or K+ supplements)
- Gynecomastia, menstrual irregularities, impotence (dose-dependent, often reversible)
- Gastrointestinal upset, diarrhea, gastritis
- Drowsiness, dizziness, headache
- Risk of severe hyponatremia and metabolic acidosis (rare)
## Key Drug Interactions
- **ACE inhibitors, ARBs, direct renin inhibitors** – additive hyperkalemia risk
- **Potassium supplements, potassium-sparing diuretics** – contraindicated in most cases
- **NSAIDs** – reduce diuretic effect and worsen renal function; increase hyperkalemia risk
- **Digoxin** – spironolactone may increase digoxin levels (monitor)
- **Lithium** – reduced clearance, potential toxicity
- **Warfarin** – no significant interaction, but monitor INR if changes in fluid status
## Monitoring
- Serum potassium and creatinine: baseline, within 1–2 weeks after initiation or dose change, and periodically thereafter (especially in renal impairment, elderly, or with interacting drugs).
- Blood pressure, weight, signs of volume depletion/hyperkalemia.
- In HFrEF: monitor for symptomatic hypotension.
- In long-term use: consider monitoring for gynecomastia.
## Clinical Pearls
- Take with food to minimize GI upset and improve absorption.
- May take 1–2 weeks for full antihypertensive effect.
- Gynecomastia is dose- and duration-dependent; consider alternate therapy (e.g., eplerenone) if problematic.
- For hyperkalemia management: reduce dose, avoid high-K+ diet, and check drug interactions.
- Do not use as monotherapy for hypertension unless primary hyperaldosteronism is confirmed.
- Pregnancy: avoid unless essential (may cause feminization of male fetus); use effective contraception if indicated.
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**Educational Disclaimer:** This information is for educational purposes and does not replace clinical judgment or local protocols. Dosing recommendations may vary based on patient-specific factors, indication, and institutional guidelines. Always verify with current prescribing information and monitor therapy closely.
