Acetyl%252525252525252525252525252525252520cysteine

# Acetylcysteine ## Overview Acetylcysteine (N-acetyl-L-cysteine) functions as a precursor to glutathione (antioxidant) and acts as a mucolytic agent by splitting disulfide bonds in mucus. It is the gold-standard antidote for acetaminophen (APAP) toxicity. ## Primary Indications * **Acetaminophen toxicity:** Prevention of hepatotoxicity following acute ingestion or repeated supratherapeutic ingestion. * **Mucolytic therapy:** Adjunct treatment for abnormal, viscid, or inspissated mucous secretions (e.g., COPD, cystic fibrosis, pneumonia). * **Prevention of contrast-induced nephropathy:** Controversial efficacy; clinical use diminishing. ## Adult Dosing * **APAP Toxicity (IV - Acetadote protocol):** * Loading: 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. * **APAP Toxicity (Oral):** * Loading: 140 mg/kg orally once. * Maintenance: 70 mg/kg every 4 hours for 17 doses. * **Mucolytic:** 1–10 mL of 20% solution or 2–20 mL of 10% solution via nebulizer every 4–6 hours. ## Pediatric Dosing * **APAP Toxicity:** Follow standard FDA-approved IV protocol (150/50/100 mg/kg) tailored to child's weight. Dilution volumes must be strictly adjusted in patients <40 kg to prevent fluid overload. * **Mucolytic:** 3–5 mL of 20% solution or 6–10 mL of 10% solution via nebulizer every 6–8 hours. ## Dose Adjustments * **Hepatic/Renal Impairment:** No standard adjustment required for APAP toxicity. * **Fluid Restriction:** In pediatric patients or those with heart failure, minimize IV fluid volume for the maintenance phases per institutional protocols. ## Contraindications * Hypersensitivity to acetylcysteine. * Oral administration is contraindicated in patients with vomiting or bowel obstruction (risk of aspiration). ## Adverse Effects * **Anaphylactoid reactions:** Common with IV administration (flushing, urticaria, angioedema, hypotension, bronchospasm). Stop infusion immediately and treat with antihistamines/epinephrine if severe. * **Gastrointestinal:** Nausea, vomiting (common with oral administration; consider antiemetics). * **Respiratory:** Bronchospasm (more common with nebulized 20% solution; consider pretreatment with a beta-2 agonist). ## Key Drug Interactions * **Activated Charcoal:** May bind acetylcysteine if administered concurrently; administer charcoal first and provide a gap if possible (though toxicity treatment takes priority). * **Nitroglycerin:** Acetylcysteine may enhance the vasodilatory/hypotensive effect of nitroglycerin. ## Monitoring * **APAP Toxicity:** Monitor plasma APAP levels (Rumack-Matthew nomogram), ALT, AST, bilirubin, prothrombin time/INR, and serum creatinine. * **Clinical:** Monitor for anaphylactoid reactions during the loading dose and vital signs throughout the infusion. ## Clinical Pearls * **Odor:** The solution has a characteristic sulfur (rotten egg) odor which may decrease patient compliance with oral dosing. * **Nebulization:** If using as a mucolytic, ensure a bronchodilator is available, as the inhalation can trigger reactive airway disease. * **IV vs. Oral:** IV is generally preferred in most hospitals to ensure compliance and avoid severe GI intolerance, though oral is standard in resource-limited settings. *** *Disclaimer: This information is for educational purposes and does not replace professional clinical judgment. Always verify dosages, contraindications, and protocol-specific weight-based dilution requirements with current local hospital guidelines and official prescribing information.*