Acetyl%252525252525252525252525252520cysteine

# Acetylcysteine ## Overview Acetylcysteine (N-acetyl-L-cysteine) is a mucolytic agent and the specific antidote for acetaminophen (APAP) toxicity. It acts by restoring hepatic glutathione stores and acting as a precursor for glutathione synthesis. ## Primary Indications * **Acetaminophen toxicity:** Acute ingestion or chronic overdose. * **Mucolytic therapy:** Adjunct for pulmonary conditions with viscid mucus (off-label via inhalation). * **Contrast-induced nephropathy (GIN):** Prophylaxis (evidence is mixed/weak). ## Adult Dosing * **Acetaminophen Toxicity (IV Protocol - 20-21 hour regimen):** * Loading: 150 mg/kg IV over 60 minutes. * Second dose: 50 mg/kg IV over 4 hours. * Third dose: 100 mg/kg IV over 16 hours. * **Acetaminophen Toxicity (Oral Protocol - 72 hour regimen):** * Loading: 140 mg/kg PO. * Maintenance: 70 mg/kg PO every 4 hours for 17 doses. * **Mucolytic (Inhalation):** 1–10 mL of 20% solution administered by nebulizer 3–4 times daily, or 2–20 mL of 10% solution every 4–6 hours. ## Pediatric Dosing * **Acetaminophen Toxicity:** Dosage is weight-based and mirrors the adult IV protocol (150 mg/kg -> 50 mg/kg -> 100 mg/kg). Ensure careful calculation to avoid volume overload in neonates/infants. * **Mucolytic (Inhalation):** 3–5 mL of 20% solution or 6–10 mL of 10% solution, 3–4 times daily via nebulizer. ## Dose Adjustments * **Renal/Hepatic:** No specific adjustments required for APAP toxicity; however, monitor fluid status closely. * **Anaphylactoid reactions:** For patients with non-allergic hypersensitivity during IV infusion, temporarily stop the infusion, administer antihistamines, and restart at a slower rate. ## Contraindications * **Absolute:** Hypersensitivity to acetylcysteine. * **Relative:** Bronchial asthma (increased risk of bronchospasm with inhaled use). ## Adverse Effects * **IV:** Anaphylactoid reactions (flushing, urticaria, angioedema, hypotension, bronchospasm), nausea, vomiting. * **Inhalation:** Bronchospasm (can be severe), rhinorrhea, stomatitis, unpleasant odor (sulfur). ## Key Drug Interactions * **Activated Charcoal:** May adsorb acetylcysteine. If both are indicated, administer charcoal first and consider increasing the acetylcysteine dose if significant charcoal remains in the GI tract. * **Inhaled Antibiotics:** Do not mix acetylcysteine with antibiotics (e.g., tetracyclines, aminoglycosides) in the same nebulizer as it may inactivate them. ## Monitoring * **APAP Toxicity:** Serial serum APAP levels, ALT/AST, INR/PT, creatinine, and electrolytes. * **IV Infusion:** Vital signs (hypotension/tachycardia) during loading dose. * **Mucolytic:** Respiratory status and auscultation for wheezing. ## Clinical Pearls * **Oral vs. IV:** Oral administration is often limited by severe nausea/vomiting. IV is preferred for patients with fulminant hepatic failure, pregnancy, or refractory vomiting. * **Inhaled Use:** Always administer a bronchodilator (e.g., albuterol) prior to inhaled acetylcysteine to reduce the risk of drug-induced bronchospasm. * **Odor:** The "rotten egg" smell is characteristic of the sulfide content; it is normal and does not indicate product degradation. *** **Educational Disclaimer:** This information is for educational purposes only. Always verify dosages, contraindications, and drug compatibility against your institution’s current protocols and the most recent manufacturer prescribing information (package insert) before clinical use.