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# Acetylcysteine ## Overview Acetylcysteine is an antidote for acetaminophen overdose and a mucolytic agent. ## Primary Indications * Acetaminophen overdose * Adjunct to antibiotics in managing certain respiratory conditions (e.g., cystic fibrosis, chronic bronchitis) ## Adult Dosing **Acetaminophen Overdose:** * **Loading Dose:** 150 mg/kg IV over 1 hour. * **Second Dose:** 50 mg/kg IV over 4 hours. * **Third Dose:** 100 mg/kg IV over 16 hours. * Total duration: 21 hours. * Maximum dose: Not to exceed 150 mg/kg/day in 3 divided doses. Higher doses may be used in severe poisoning, consult specialist recommendations. **Mucolytic:** * **Nebulized:** 3 to 5 mL of 20% solution or 6 to 10 mL of 10% solution every 2 to 6 hours as needed. * **Oral:** 200 mg to 400 mg two to four times daily. ## Pediatric Dosing **Acetaminophen Overdose:** * Dosing is the same as adults on a mg/kg basis. **Mucolytic:** * **Nebulized:** 10% solution: 1 to 2 mL every 2 to 6 hours. 20% solution: 1 mL every 2 to 6 hours. * **Oral:** 50 mg/kg orally twice daily, up to 200 mg per dose. ## Dose Adjustments No specific dose adjustments are generally required for hepatic or renal impairment, but caution may be warranted. ## Contraindications Hypersensitivity to acetylcysteine. ## Adverse Effects * **IV:** Anaphylactoid reactions (rash, pruritus, bronchospasm, dyspnea, angioedema, hypotension), flushing, chest tightness, fever. * **Nebulized:** Bronchospasm (especially in asthmatics), stomatitis, nausea, vomiting, rhinorrhea. * **Oral:** Nausea, vomiting, diarrhea, rash. ## Key Drug Interactions * **Activated Charcoal:** May adsorb oral acetylcysteine, reducing absorption. Separate administration if possible. ## Monitoring * **Acetaminophen Overdose:** * Serum acetaminophen levels (obtain 4 hours post-ingestion and every 4-8 hours thereafter). * Liver function tests (LFTs), INR, creatinine, electrolytes, glucose, and arterial blood gases (ABGs) if indicated. * Monitor for signs of anaphylactoid reaction during IV infusion. * **Mucolytic:** * Pulmonary status, effectiveness of secretion mobilization. * Monitor for bronchospasm. ## Clinical Pearls * The IV formulation for acetaminophen overdose is critical; oral administration is less effective due to first-pass metabolism. * Antihistamines or corticosteroids may be administered prophylactically to reduce the incidence of anaphylactoid reactions with IV acetylcysteine. * N-acetylcysteine is a precursor to glutathione, which conjugates with NAPQI (toxic metabolite of acetaminophen), rendering it inactive. *** **Disclaimer:** This information is for educational purposes only and does not substitute for professional medical advice. Always consult current prescribing information and guidelines before administering any medication. Dosing may vary based on institutional protocols and individual patient factors.