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# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent that works by breaking disulfide bonds in mucus, decreasing its viscosity. It also acts as an antidote for acetaminophen overdose by replenishing glutathione stores. ## Primary Indications * **Acetaminophen Overdose:** To prevent or reduce liver damage. * **Mucolytic:** To thin mucus in respiratory conditions such as chronic bronchitis, emphysema, and cystic fibrosis. ## Adult Dosing **Acetaminophen Overdose:** * **Loading Dose:** 150 mg/kg IV infused over 1 hour. * **Second Dose:** 50 mg/kg IV infused over 4 hours. * **Third Dose:** 100 mg/kg IV infused over 16 hours. * Total daily dose should not exceed 300 mg/kg. * The regimen may be adjusted based on acetaminophen levels and time since ingestion. Consult local protocol for specific adjustments. **Mucolytic:** * **Inhalation:** 3 mL to 5 mL of 20% solution or 6 mL to 10 mL of 10% solution, nebulized every 2 to 6 hours. * **Oral:** Typically 600 mg once daily or in divided doses. ## Pediatric Dosing **Acetaminophen Overdose:** * Dosing is the same as adult dosing (150 mg/kg, 50 mg/kg, 100 mg/kg). Ensure accurate weight-based calculations. **Mucolytic:** * **Inhalation:** 1 mL to 2 mL of 20% solution or 2 mL to 5 mL of 10% solution, nebulized every 2 to 6 hours. ## Dose Adjustments No specific dose adjustments are routinely required for renal or hepatic impairment for the mucolytic indication. For acetaminophen overdose, dose adjustments are guided by serum acetaminophen levels and clinical response. ## Contraindications * Hypersensitivity to acetylcysteine. * Active gastrointestinal bleeding (for oral formulations, caution advised). ## Adverse Effects **IV Acetylcysteine:** Anaphylactoid reactions (rash, pruritus, urticaria, bronchospasm, angioedema), flushing, tachycardia, hypotension, nausea, vomiting. **Inhaled Acetylcysteine:** Bronchospasm (especially in patients with asthma), nausea, vomiting, stomatitis. **Oral Acetylcysteine:** Nausea, vomiting, diarrhea, rash. ## Key Drug Interactions * **Activated Charcoal:** May reduce the absorption of oral acetylcysteine. * **Nitroglycerin:** May potentiate the vasodilatory effects and lead to hypotension. ## Monitoring * **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests (AST, ALT, bilirubin, INR), clinical signs of liver injury, and patient's overall clinical status. * **Mucolytic:** Pulmonary status, respiratory rate, oxygen saturation, and presence of bronchospasm. ## Clinical Pearls * For IV administration in acetaminophen overdose, premedication with an antihistamine may reduce the incidence of anaphylactoid reactions. * The characteristic sulfurous odor of acetylcysteine is normal. * When used for mucolysis, ensure adequate hydration to maximize effectiveness. * Always verify the formulation (oral, IV, inhalation) and concentration being used. *** *This information is intended for healthcare professionals and does not replace clinical judgment or a thorough review of the most current prescribing information, including full prescribing details, contraindications, warnings, and precautions.*