Acetyl%2525252525252525252525252520cysteine

# Acetylcysteine ## Overview Acetylcysteine (N-acetyl-L-cysteine) is a mucolytic agent and the specific antidote for acetaminophen (APAP) toxicity. It acts as a glutathione precursor, maintaining or restoring hepatic glutathione levels to neutralize the toxic metabolite NAPQI. ## Primary Indications * **Acetaminophen overdose:** Management of acute ingestion or chronic toxicity. * **Mucolytic therapy:** Adjunct for abnormal, viscid, or inspissated mucous secretions in bronchopulmonary diseases (inhalation). * **Contrast-induced nephropathy (CIN) prophylaxis:** (Debated efficacy; oral use). ## Adult Dosing * **APAP Toxicity (IV Protocol - 20 hour):** * Loading: 150 mg/kg in 200 mL D5W over 60 mins. * Second dose: 50 mg/kg in 500 mL D5W over 4 hours. * Third dose: 100 mg/kg in 1000 mL D5W over 16 hours. * *Note: Adjusted if APAP remains detectable.* * **APAP Toxicity (Oral Protocol - 72 hour):** 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses. * **Mucolytic (Inhalation):** 1–10 mL of 20% solution nebulized 3–4 times daily or 2–20 mL of 10% solution. ## Pediatric Dosing * **APAP Toxicity:** Same weight-based dosing as adults. * *Caution:* Fluid restriction may be necessary in small children; total volume of diluent must be adjusted based on weight to avoid hyponatremia. Ensure institutional protocol guidance. ## Dose Adjustments * **Renal/Hepatic:** No formal dose adjustments required for APAP toxicity; however, fluid overload risk requires careful monitoring in patients with heart/renal failure during titration. * **Anaphylactoid Reaction:** If a reaction occurs during IV infusion, pause, administer antihistamines/corticosteroids, and restart at a slower rate per institutional protocol. ## Contraindications * **IV:** No absolute contraindications for APAP toxicity given the severity of the condition. * **Inhalation:** Hypersensitivity to acetylcysteine. ## Adverse Effects * **IV:** Anaphylactoid reactions (flushing, pruritus, rash, angioedema, hypotension, bronchospasm), nausea, vomiting. * **Inhalation:** Bronchospasm (due to acidity/osmolarity), stomatitis, rhinorrhea, hemoptysis. * **Oral:** Severe nausea and vomiting (frequent; consider antiemetics). ## Key Drug Interactions * **Activated Charcoal:** May bind acetylcysteine if given orally; administer charcoal at least 1 hour before acetylcysteine if both are indicated. * **Inhaled Antibiotics:** Physically incompatible with certain antibiotics (e.g., tetracyclines, erythromycin); administer separately. ## Monitoring * **APAP Toxicity:** Serum acetaminophen level, ALT/AST, INR/PT, creatinine, and electrolytes. * **Infusion:** Monitor closely for signs of anaphylactoid reaction during the loading dose. * **Respiratory:** Monitor for bronchospasm during nebulization (consider pretreating with a short-acting beta-agonist). ## Clinical Pearls * **Efficacy:** Acetylcysteine is most effective when administered within 8 hours of acetaminophen ingestion. * **Odor:** The formulation contains a sulfur moiety, resulting in a characteristic "rotten egg" smell; this is normal. * **IV vs. Oral:** IV is preferred in the US due to reliability of administration and better tolerance, despite the risk of anaphylactoid reactions. * **Dilution:** Always verify the correct concentration (10% vs 20%) to prevent dosing errors, especially in pediatric populations. *** **Disclaimer:** This information is for educational purposes only. Always verify dosing and administration protocols against current institutional guidelines, drug monographs, and clinical decision-support systems before prescribing or administering medication.