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# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent that works by breaking disulfide bonds in mucus, reducing its viscosity. It is also the antidote for acetaminophen overdose. ## Primary Indications * **Acetaminophen Overdose:** Treatment to prevent or reduce liver toxicity. * **Mucolytic Agent:** To thin mucus in respiratory conditions like COPD, cystic fibrosis, and pneumonia. ## Adult Dosing * **Acetaminophen Overdose:** * **Loading Dose:** 150 mg/kg IV infused over 60 minutes. * **Second Dose:** 50 mg/kg IV infused over 60 minutes, 4 hours after the loading dose. * **Subsequent Doses:** 100 mg/kg IV infused over 15-24 hours. Total duration typically 72 hours. Specific protocols may vary. * **Mucolytic:** * **Inhaled:** 3-5 mL of 20% solution or 6-10 mL of 10% solution nebulized every 2-6 hours. * **Oral:** 200 mg twice daily to 600 mg three times daily. ## Pediatric Dosing * **Acetaminophen Overdose:** Dosing is the same as adults (150 mg/kg IV loading dose, followed by 50 mg/kg IV, then 100 mg/kg IV over 20 hours). * **Mucolytic:** * **Inhaled:** 1-2 mL of 20% solution or 2-4 mL of 10% solution nebulized every 2-6 hours. ## Dose Adjustments No specific dose adjustments are typically required for renal or hepatic impairment for the mucolytic indication. For acetaminophen overdose, prolonged or higher doses may be necessary in severe cases or if acetaminophen levels remain elevated. ## Contraindications Hypersensitivity to acetylcysteine. ## Adverse Effects * **Inhaled:** Bronchospasm, bronchoconstriction, nausea, vomiting, stomatitis. * **IV:** Anaphylactoid reactions (rash, pruritus, angioedema, bronchospasm, dyspnea, hypotension), fever, urticaria. * **Oral:** Nausea, vomiting, diarrhea, abdominal pain, rash. ## Key Drug Interactions * **Activated Charcoal:** May adsorb oral acetylcysteine, reducing its absorption. Separate administration by at least 1 hour. * **Nitroglycerin:** May potentiate hypotensive effects. ## Monitoring * **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests (ALT, AST, bilirubin, INR), prothrombin time, glucose. Monitor for signs of anaphylaxis. * **Mucolytic:** Respiratory status, sputum consistency and ease of expectoration. Monitor for bronchospasm. ## Clinical Pearls * For IV acetylcysteine, dilution is often recommended to reduce the risk of anaphylactoid reactions. Always follow institutional protocols. * Administer inhaled acetylcysteine cautiously in patients with reactive airway disease due to the risk of bronchospasm. Bronchodilators may be co-administered. * The effectiveness of IV acetylcysteine is greatest when initiated within 8 hours of acetaminophen ingestion. * Anaphylactoid reactions to IV acetylcysteine are common but usually manageable; do not discontinue treatment unless severe. *** **Disclaimer:** This information is intended for clinical use and does not replace professional medical judgment. Always consult the most current prescribing information and institutional guidelines for definitive patient care decisions.