Acetyl%2520cysteine

# Acetylcysteine ## Overview Acetylcysteine (N-acetylcysteine, NAC) is a mucolytic agent and the antidote for acetaminophen (paracetamol) overdose. It works by reducing disulfide bonds in mucus (mucolytic) and replenishing hepatic glutathione (antidote). ## Primary Indications - **Acetaminophen overdose** (IV or oral) – to prevent hepatotoxicity - **Mucolytic** – for abnormal, thick mucus secretions (e.g., cystic fibrosis, COPD, bronchiectasis) - **Off-label**: Prevention of contrast-induced nephropathy, psychiatric disorders (limited evidence) ## Adult Dosing **Acetaminophen overdose (IV protocol – e.g., standard 21-hour regimen):** - Loading dose: 150 mg/kg in 200 mL D5W over 60 minutes - Second dose: 50 mg/kg in 500 mL D5W over 4 hours - Third dose: 100 mg/kg in 1000 mL D5W over 16 hours - *Exact protocol varies by institution; follow local guidelines.* **Acetaminophen overdose (oral protocol):** - Loading: 140 mg/kg PO (one dose) - Maintenance: 70 mg/kg PO every 4 hours for 17 doses (total 72 hours) **Mucolytic (oral):** 600–1200 mg daily in divided doses (e.g., 600 mg BID). Maximum: 1200 mg/day. **Mucolytic (inhalation):** 3–5 mL of 20% solution or 6–10 mL of 10% solution via nebulizer, 3–4 times daily. ## Pediatric Dosing **Acetaminophen overdose (IV):** Same weight-based dosing as adults (150/50/100 mg/kg over 21 hours). Use D5W volumes adjusted for weight. **Acetaminophen overdose (oral):** Same weight-based dosing as adults (140 mg/kg load, then 70 mg/kg q4h x 17 doses). **Mucolytic (inhalation):** 1–3 mL of 20% solution or 2–6 mL of 10% solution via nebulizer, 3–4 times daily. Maximum: 10 mL per dose. **Mucolytic (oral):** Not routinely recommended; if used, 10–20 mg/kg/day in divided doses (limited evidence). ## Dose Adjustments - **Hepatic impairment:** No specific adjustment for mucolytic use. In acetaminophen overdose, dosing is based on toxicity protocol; monitor liver function. - **Renal impairment:** No adjustment needed. - **Asthma/COPD:** Use with caution; may induce bronchospasm (especially with nebulized form). ## Contraindications - **Hypersensitivity** to acetylcysteine or any component - **Severe asthma** or history of bronchospasm (relative; use caution with nebulized form) - **Active peptic ulcer** (relative; oral form may irritate) ## Adverse Effects - **Common:** Nausea, vomiting (especially with oral loading dose), rash, flushing - **Serious:** Anaphylactoid reaction (bronchospasm, hypotension, angioedema) – more common with IV, usually within first hour; treat by stopping infusion, antihistamines, bronchodilators - **Nebulized:** Cough, bronchospasm, stomatitis ## Key Drug Interactions - **Activated charcoal:** May reduce absorption of oral acetylcysteine; separate by 1–2 hours if used together in overdose - **Nitroglycerin:** Acetylcysteine may potentiate hypotension and headache - **Carbamazepine:** Possible decreased carbamazepine levels (limited data) ## Monitoring - **Acetaminophen overdose:** Serum acetaminophen level, liver function tests (ALT, AST), INR, renal function; monitor for anaphylactoid reaction during IV infusion - **Mucolytic use:** Clinical response (sputum clearance, cough); pulmonary function if nebulized ## Clinical Pearls - **IV acetylcysteine** can cause anaphylactoid reactions (not true IgE-mediated allergy); often managed by slowing infusion and giving antihistamines – do not automatically discontinue if mild. - **Oral acetylcysteine** has a strong sulfur odor; mix with juice or cola to improve palatability. - **Nebulized acetylcysteine** may be mixed with bronchodilators (e.g., albuterol) to reduce bronchospasm risk. - **Acetaminophen overdose:** Start acetylcysteine within 8 hours of ingestion for maximum efficacy; benefit may still exist after 24 hours. - **Contrast-induced nephropathy:** Not routinely recommended; evidence mixed. --- *This information is for educational purposes only. Always verify current prescribing information, local protocols, and institutional guidelines before administering acetylcysteine.*