Acetyl%25252525252525252525252525252525252520cysteine

# Acetylcysteine ## Overview Acetylcysteine (N-acetyl-L-cysteine) is a mucolytic agent and, critically, a precursor to glutathione used as the primary antidote for acetaminophen (APAP) toxicity. It acts by replenishing hepatic glutathione stores to neutralize toxic NAPQI metabolites. ## Primary Indications * **Acetaminophen Overdose:** Antidote for hepatotoxicity. * **Mucolytic Therapy:** Adjunct treatment for abnormal, viscid, or inspissated mucus secretions (e.g., COPD, cystic fibrosis, pneumonia). ## Adult Dosing * **Acetaminophen Overdose (IV - Acetadote protocol):** * 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. * **Mucolytic (Nebulization):** 3-5 mL of 20% solution or 6-10 mL of 10% solution administered 3–4 times daily. ## Pediatric Dosing * **Acetaminophen Overdose:** Follows the same weight-based IV protocol as adults (Loading: 150 mg/kg; Maintenance: 50 mg/kg then 100 mg/kg). Dilution volumes should be adjusted based on the child's fluid status/weight (e.g., reduce carrier fluid volume for smaller children). * **Mucolytic (Nebulization):** 1–2 mL of 20% solution or 2–4 mL of 10% solution administered 3–4 times daily. ## Dose Adjustments * **Hepatic Impairment:** No specific adjustment necessary for toxicity treatment, as it is the indicated therapy for hepatic injury. * **Renal Impairment:** No standard adjustment required for APAP overdose, but monitor closely for fluid overload if utilizing high-volume IV protocols. ## Contraindications * **Hypersensitivity:** Known history of severe anaphylactoid reactions to acetylcysteine. * **Oral/Nebulized:** History of bronchospasm (use with caution; observe for worsening bronchoconstriction). ## Adverse Effects * **IV/Systemic:** Anaphylactoid reactions (flushing, pruritus, rash, angioedema, hypotension, bronchospasm). More common during the loading dose. * **Inhalation:** Bronchospasm (pre-treat with short-acting beta-agonist), stomatitis, rhinorrhea, nausea, and vomiting. * **Odor:** Distinctive sulfur ("rotten egg") smell is common and often unpleasant to patients. ## Key Drug Interactions * **Activated Charcoal:** May adsorb acetylcysteine. If both are indicated, administer charcoal first and then give oral acetylcysteine; consider increasing the dose of oral acetylcysteine if charcoal was recently administered. * **Nitroglycerin:** Acetylcysteine may enhance the vasodilatory and antiplatelet effects of nitroglycerin, potentially causing significant hypotension or headache. ## Monitoring * **APAP Toxicity:** Serum APAP levels, AST/ALT, prothrombin time/INR, serum creatinine, and electrolytes. * **Anaphylactoid Reaction:** Monitor vitals continuously during the loading dose infusion. Stop infusion and initiate supportive care (e.g., antihistamines, corticosteroids, or epinephrine) if a reaction occurs. ## Clinical Pearls * **IV vs. Oral:** The IV route is preferred for patients who are vomiting, have altered mental status, or require rapid therapy. * **Dilution:** For pediatric patients or those with volume restrictions, use standardized hospital-specific concentration protocols to avoid fluid overload. * **Nebulized use:** Always administer a bronchodilator prior to or concurrently with acetylcysteine to mitigate the risk of medication-induced bronchospasm. *** **Educational Disclaimer:** This information is for educational purposes only. Dosing protocols, especially for acetaminophen overdose, vary by institution and patient weight-based requirements (e.g., the Rumack-Matthew nomogram). Always verify current institutional protocols and the patient's individual clinical status against official prescribing information and toxicology consultation services before administration.