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# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent used to break down thick mucus in the airways. It is also the antidote for acetaminophen overdose. ## Primary Indications * Management of acetaminophen overdose. * Adjuvant therapy in patients with chronic bronchitis, emphysema, or cystic fibrosis to loosen bronchial secretions. ## Adult Dosing **Acetaminophen Overdose:** * **Oral:** Loading dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses (total of 72 hours). * **Intravenous:** Standard protocol involves a 3-bag infusion. * Bag 1: 150 mg/kg over 60 minutes. * Bag 2: 50 mg/kg over the next 4 hours. * Bag 3: 100 mg/kg over the subsequent 16 hours. * *Note: IV protocols can vary; consult local institutional guidelines.* **Mucolytic Therapy:** * **Oral:** 200 mg to 400 mg twice or three times daily. * **Intravenous:** Not typically used for mucolytic indications. * **Nebulization:** 10% solution: 3-5 mL every 3-4 hours. 20% solution: 1-2 mL every 3-4 hours. Can be administered undiluted or diluted with sterile water or saline for inhalation. ## Pediatric Dosing **Acetaminophen Overdose:** * **Oral:** Same as adult dosing: Loading dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses. * **Intravenous:** Same as adult dosing. Consult local institutional guidelines for specific IV protocols in pediatric patients. **Mucolytic Therapy:** * **Oral:** 50 mg/kg to 100 mg/kg per dose, up to 600 mg/day, given in 2-3 divided doses. * **Nebulization:** * 10% solution: 1-2 mL every 3-4 hours. * 20% solution: 0.5-1 mL every 3-4 hours. ## Dose Adjustments No specific dose adjustments are routinely required for hepatic or renal impairment, but caution is advised. ## Contraindications Hypersensitivity to acetylcysteine. ## Adverse Effects * **Common:** Nausea, vomiting, stomatitis, rash, pruritus, urticaria. * **Less Common:** Bronchospasm, rhinorrhea, drowsiness, fever. * **Rare:** Anaphylactoid reactions (especially with IV administration). ## Key Drug Interactions * **Activated Charcoal:** May bind to oral acetylcysteine, reducing its absorption. If co-administered for overdose, consider separating doses or administering acetylcysteine after charcoal has been emptied from the stomach. ## Monitoring * **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests (LFTs), prothrombin time (PT), INR, glucose, electrolytes, and renal function. Monitor for signs of hepatotoxicity. * **Mucolytic Therapy:** Pulmonary status, sputum production, and patient tolerance. ## Clinical Pearls * The characteristic sulfurous (rotten egg) odor is normal. * For nebulized acetylcysteine, a bronchospasm may occur. Pretreatment with a bronchodilator may be beneficial. * IV acetylcysteine for acetaminophen overdose can cause anaphylactoid reactions; monitor closely and consider premedication with antihistamines if indicated. * Oral acetylcysteine is most effective when given within 8-10 hours of acetaminophen ingestion. *** **Disclaimer:** This information is for educational purposes only and does not constitute medical advice. Always consult the current official prescribing information and relevant institutional guidelines for complete and up-to-date drug information before making any treatment decisions.