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# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucoproteins, decreasing mucus viscosity. It is also an antidote for acetaminophen overdose by replenishing glutathione stores. ## Primary Indications * Acetaminophen overdose * Mucolytic agent for conditions with thick mucus secretions (e.g., cystic fibrosis, chronic obstructive pulmonary disease, pneumonia) ## Adult Dosing **Acetaminophen Overdose:** * **Oral:** Loading dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses. * **Intravenous:** 150 mg/kg IV infused over 1 hour, followed by 50 mg/kg IV infused over the next 4 hours, then 100 mg/kg IV infused over the next 16 hours. Specific IV protocols may vary by institution. **Mucolytic:** * **Inhaled:** 3 mL of a 20% solution or 6 mL of a 10% solution nebulized every 2 to 6 hours. Higher doses may be used based on clinical response and tolerance. ## Pediatric Dosing **Acetaminophen Overdose:** * **Oral:** Loading dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses. * **Intravenous:** 150 mg/kg IV infused over 1 hour, followed by 50 mg/kg IV infused over the next 4 hours, then 100 mg/kg IV infused over the next 16 hours. Specific IV protocols may vary by institution. **Mucolytic:** * **Inhaled:** 10% solution: 1 mL to 2 mL nebulized every 2 to 6 hours. 20% solution: 1 mL nebulized every 2 to 6 hours. ## Dose Adjustments No specific dose adjustments are routinely recommended for hepatic or renal impairment. However, caution is advised in severe impairment. ## Contraindications * Hypersensitivity to acetylcysteine or components of the formulation. * Acute bronchospasm (for inhaled form). ## Adverse Effects * **Inhaled:** Bronchospasm, nausea, vomiting, stomatitis, rhinorrhea, drowsiness. * **Intravenous:** Anaphylactoid reactions (rash, urticaria, pruritus, angioedema, bronchospasm, dyspnea, tachycardia), nausea, vomiting, fever, dizziness. ## Key Drug Interactions * Activated charcoal can decrease the absorption of oral acetylcysteine. ## Monitoring * **Acetaminophen Overdose:** Acetaminophen levels, liver function tests (LFTs), prothrombin time (PT), international normalized ratio (INR), and clinical signs of liver toxicity. * **Mucolytic:** Respiratory status, sputum consistency and volume. ## Clinical Pearls * For inhaled acetylcysteine, pre-treatment with a bronchodilator may be necessary in patients prone to bronchospasm. * Intravenous acetylcysteine for acetaminophen overdose should be initiated as soon as possible, ideally within 8 hours of ingestion. * The characteristic sulfurous odor of acetylcysteine can be unpleasant; consider this when administering. *** **Disclaimer:** This information is intended for clinical pharmacists and should not replace consultation with the official prescribing information or institutional protocols. Always verify current drug information before making clinical decisions.