Acetyl%2525252525252525252525252525252525252525252520cysteine

# Acetylcysteine ## Overview Acetylcysteine (N-acetyl-L-cysteine) is a mucolytic agent and a precursor to glutathione. It functions by splitting disulfide bonds in mucoproteins (lowering viscosity) and by restoring hepatic glutathione stores to neutralize the toxic metabolite of acetaminophen (NAPQI). ## Primary Indications * **Acetaminophen Overdose:** Antidote for hepatotoxicity. * **Mucolytic Therapy:** Adjunct for abnormal, viscid, or inspissated mucous secretions (e.g., CF, COPD, bronchitis). * **Contrast-Induced Nephropathy (Off-label):** Prophylaxis in high-risk patients. ## Adult Dosing * **Acetaminophen Overdose (IV 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. * **Acetaminophen Overdose (Oral Protocol):** * Loading: 140 mg/kg. Maintenance: 70 mg/kg every 4 hours for 17 additional doses. * **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:** Follow the same IV weight-based dosing as adults. Adjust diluent volumes based on fluid restriction needs (e.g., reduce D5W volume for smaller children). * **Mucolytic (Inhalation):** Older children: 3-5 mL of 20% solution or 6-10 mL of 10% solution via nebulizer 3–4 times daily. ## Dose Adjustments * **Renal/Hepatic:** No formal adjustment required for mucolytic use. For acetaminophen overdose, continue infusions regardless of current hepatic/renal status, as the drug is required to mitigate ongoing toxicity. ## Contraindications * **Hypersensitivity:** Known history of severe anaphylactoid reaction to acetylcysteine components. * **Inhalation:** Use with caution in patients with asthma due to potential for bronchospasm. ## Adverse Effects * **IV/Systemic:** Anaphylactoid reactions (flushing, urticaria, angioedema, hypotension, bronchospasm, tachycardia). Commonly associated with infusion rate. * **Inhalation:** Stomatitis, rhinorrhea, nausea, vomiting, chest tightness, and bronchospasm (if administered without a bronchodilator). * **GI:** If oral, high incidence of nausea and vomiting (consider antiemetics). ## Key Drug Interactions * **Bronchodilators:** Acetylcysteine may cause bronchospasm; administer a short-acting beta-agonist 10–15 minutes prior to nebulized acetylcysteine. * **Activated Charcoal:** Charcoal may adsorb oral acetylcysteine. Administer charcoal at least 1 hour prior to oral acetylcysteine if both are indicated. ## Monitoring * **Acetaminophen Overdose:** Serum acetaminophen levels, AST/ALT, bilirubin, prothrombin time/INR, creatinine, and electrolytes. Monitor for anaphylactoid reactions during IV infusion. * **Mucolytic:** Lung sounds, cough effectiveness, and respiratory distress. ## Clinical Pearls * **Anaphylactoid Reaction Management:** If a reaction occurs during IV administration, stop the infusion, administer antihistamines (e.g., diphenhydramine) and/or epinephrine/steroids as required, then restart at a slower rate if the reaction is mild. * **Incompatibility:** Do not mix acetylcysteine with iron, copper, or rubber fittings (use glass or plastic). * **Odor:** The drug has a characteristic sulfurous (rotten egg) odor which may be poorly tolerated by some patients during inhalation. *** *Disclaimer: This information is for educational purposes only. Dosing protocols can vary significantly by institution and severity of clinical presentation. Always consult the most recent institutional guidelines, hospital-specific protocols, or the prescribing information/package insert before administering medication.*