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# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent that loosens thick mucus, and an antidote for acetaminophen overdose. ## Primary Indications * Acetaminophen overdose * Adjunct to other therapies for patients with **pulmonary conditions** that are characterized by thick or excessive mucus secretions (e.g., cystic fibrosis, chronic obstructive pulmonary disease, pneumonia, tracheostomy care). ## Adult Dosing **Acetaminophen Overdose:** * **Oral:** Loading dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for a total of 17 doses. * **Intravenous (IV):** A common protocol involves a loading dose of 150 mg/kg over 1 hour, followed by 12.5 mg/kg/hour for 4 hours, then 6.25 mg/kg/hour for 16 hours. Alternative IV regimens exist and local protocols should be followed. **Mucolytic:** * **Inhalation:** 1 to 10 mL of a 20% solution or 2 to 10 mL of a 10% solution every 2 to 6 hours as needed. * **Oral:** 200 mg to 600 mg by mouth two to three times daily. ## Pediatric Dosing **Acetaminophen Overdose:** * **Oral:** Same as adult: 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses. * **Intravenous (IV):** Same as adult: Loading dose 150 mg/kg over 1 hour, followed by 12.5 mg/kg/hour for 4 hours, then 6.25 mg/kg/hour for 16 hours. Alternative IV regimens exist and local protocols should be followed. **Mucolytic:** * **Inhalation:** 1 mL of a 20% solution or 2-5 mL of a 10% solution every 2 to 6 hours as needed. * **Oral:** 50 mg/kg twice daily, up to 600 mg/day. ## Dose Adjustments No specific dose adjustments are routinely recommended for hepatic or renal impairment, but caution is advised. ## Contraindications * Hypersensitivity to acetylcysteine or any component of the formulation. * A history of bronchospasm with acetylcysteine therapy. ## Adverse Effects * **Common:** Nausea, vomiting, rash, urticaria, bronchospasm, rhinorrhea. * **Serious:** Anaphylactoid reactions, angioedema. ## Key Drug Interactions * **Activated Charcoal:** May bind to oral acetylcysteine, reducing its absorption. Administer acetylcysteine at least 1 hour after activated charcoal. * **Nitroglycerin:** May potentiate the hypotensive effect of nitroglycerin. ## Monitoring * **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests, prothrombin time, and clinical signs of liver toxicity. * **Mucolytic Use:** Respiratory status, sputum viscosity, and frequency of pulmonary exacerbations. * Monitor for signs of hypersensitivity or anaphylactoid reactions with IV administration. ## Clinical Pearls * The odor of acetylcysteine can be unpleasant. * For IV administration in acetaminophen overdose, a continuous infusion is often preferred over intermittent boluses to maintain therapeutic levels and reduce anaphylactoid reactions. * Bronchodilators may be administered prior to inhaled acetylcysteine if bronchospasm is a concern. * IV acetylcysteine can cause anaphylactoid reactions; patients should be monitored closely. *** **Disclaimer:** This information is intended for educational purposes and does not substitute for professional medical advice. Always consult the most current prescribing information and local protocols before administering any medication.