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# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucoproteins, reducing mucus viscosity. It is also a precursor to glutathione, an antioxidant, and is used as an antidote for acetaminophen overdose. ## Primary Indications * **Acetaminophen overdose:** Antidote. * **Mucolytic:** To thin mucus in conditions like COPD, cystic fibrosis, and pneumonia. ## Adult Dosing ### Acetaminophen Overdose (Oral or IV) * **Oral:** Loading dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses. Total daily dose depends on body weight. * **IV:** Loading dose of 150 mg/kg over 1 hour, followed by 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours. Maximum initial dose: 150 mg/kg. Subsequent doses up to 100 mg/kg. * *Note:* Specific protocols may vary; consult local guidelines. ### Mucolytic (Nebulized) * 3-10 mL of 10% or 20% solution every 2-6 hours as needed. * Alternatively, 1-2 mL of 10% or 20% solution via nebulizer every 3-4 hours. * *Note:* Dosing is highly individualized based on patient response and clinical status. ## Pediatric Dosing ### Acetaminophen Overdose (Oral or IV) * **Oral:** Loading dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses. * **IV:** Loading dose of 150 mg/kg over 1 hour, followed by 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours. * *Note:* Weight-based dosing is crucial. ### Mucolytic (Nebulized) * **Infants and young children:** 1-2 mL of 10% or 20% solution every 3-4 hours. * **Older children:** 3-5 mL of 10% solution or 1-2 mL of 20% solution every 3-4 hours. * *Note:* Dosing is highly individualized. ## Dose Adjustments No specific dose adjustments are generally required for renal or hepatic impairment. However, caution is advised in severe impairment due to potential accumulation. ## Contraindications * Hypersensitivity to acetylcysteine or any component of the formulation. * Active hemorrhage (especially with nebulized form). ## Adverse Effects * **Nebulized:** Bronchospasm, bronchoconstriction, nausea, vomiting, stomatitis, rhinorrhea. * **IV (Acetaminophen overdose):** Anaphylactoid reactions (rash, pruritus, urticaria, angioedema, bronchospasm, dyspnea), hypotension, tachycardia. * **Oral (Acetaminophen overdose):** Nausea, vomiting. ## Key Drug Interactions * **Activated charcoal:** May reduce the absorption of oral acetylcysteine. * **Nitroglycerin:** Potential for additive hypotensive effects. ## Monitoring * **Acetaminophen overdose:** Serum acetaminophen levels, liver function tests (ALT, AST, bilirubin), INR, glucose, creatinine, electrolytes, and clinical signs of liver toxicity. * **Mucolytic:** Respiratory status, sputum viscosity and volume, signs of bronchospasm. ## Clinical Pearls * For nebulized acetylcysteine, co-administration with a bronchodilator may be necessary to mitigate bronchospasm. * Dilution of nebulized acetylcysteine may be required for patient comfort. * The smell of acetylcysteine can be unpleasant; this does not indicate degradation. * The duration of therapy for acetaminophen overdose is typically 21 hours (oral) or 72 hours (IV). *** *This information is for educational purposes only and does not substitute for professional medical advice. Always consult the most current prescribing information and clinical guidelines before making any treatment decisions.*