Acetyl%25252525252525252525252520cysteine

# Acetylcysteine ## Overview Acetylcysteine (N-acetyl-L-cysteine/NAC) is a mucolytic agent and the primary antidote for acetaminophen (APAP) toxicity. It acts as a glutathione precursor, maintaining or restoring hepatic glutathione levels utilized to neutralize the toxic metabolite NAPQI. ## Primary Indications 1. Acetaminophen (APAP) overdose (oral or IV). 2. Mucolytic therapy (inhalation). 3. Contrast-induced nephropathy prophylaxis (controversial; evidence is inconsistent). ## Adult Dosing * **Acetaminophen Toxicity (IV Protocol - 20-hour / 3-bag regimen):** * 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 Toxicity (Oral Protocol - 72-hour regimen):** * Loading: 140 mg/kg orally. * Maintenance: 70 mg/kg every 4 hours for 17 doses. * **Mucolytic:** 3–5 mL of 20% solution or 6–10 mL of 10% solution via nebulizer 3–4 times daily. ## Pediatric Dosing * **Acetaminophen Toxicity:** Dosage is weight-based and mirrors the adult IV/oral protocol (150 mg/kg load then maintenance). *Note: Ensure careful dilution in smaller volumes for neonates/infants to prevent fluid overload.* * **Mucolytic:** 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 dose adjustments generally required for APAP toxicity; however, monitor fluid status closely in patients with renal failure. * **Infusion Reaction:** If a reaction occurs during IV loading, stop infusion, administer antihistamines/corticosteroids, and consider restarting at a slower rate once symptoms resolve. ## Contraindications * Hypersensitivity to acetylcysteine. * Oral administration is contraindicated in patients with vomiting or GI obstruction. ## Adverse Effects * **IV:** Anaphylactoid reactions (flushing, urticaria, angioedema, bronchospasm, hypotension), nausea, and vomiting. * **Inhalation:** Bronchospasm (especially in asthma), stomatitis, rhinorrhea, and unpleasant ("rotten egg") odor. ## Key Drug Interactions * **Activated Charcoal:** May reduce absorption of oral acetylcysteine if given concurrently. Administer charcoal first; if charcoal is given, wait ~1 hour before oral NAC. * **Inhaled Antibiotics:** Do not mix directly with antibiotics (e.g., tetracyclines, erythromycin) in a nebulizer; physical incompatibility may occur. ## Monitoring * **APAP Toxicity:** Serum APAP levels, ALT/AST, INR, creatinine, and electrolytes. * **IV Infusion:** Vital signs (BP, HR) and monitoring for signs of anaphylactoid reaction every 15 minutes during the loading dose. * **Pulmonary:** Monitor for bronchospasm and sputum production if used as a mucolytic. ## Clinical Pearls * **Timing:** For APAP overdose, NAC is most effective if initiated within 8 hours of ingestion. * **Odor:** The sulfurous smell is normal. If tolerated poorly via mask, try an oral mouthpiece. * **Compatibility:** IV bags should be prepared daily; discard leftover solutions. * **Caution:** Always confirm the protocol with local poison control or hospital-specific guidelines, as variations in infusion times exist. *** *Disclaimer: This information is for educational purposes only. Clinical protocols for APAP toxicity dosing can vary significantly by institution and severity of presentation. Always verify current prescribing information and institutional guidelines before administration.*