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# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent and an antidote for acetaminophen overdose. It is available as an oral or intravenous formulation. ## Primary Indications * **Acetaminophen Overdose:** Treatment of acetaminophen toxicity. * **Mucolytic:** Adjunct treatment for conditions with thick mucus secretions (e.g., chronic bronchitis, emphysema, cystic fibrosis, pneumonia). ## Adult Dosing **Acetaminophen Overdose:** * **Intravenous (IV):** Load of 150 mg/kg infused over 1 hour, followed by 50 mg/kg infused over 4 hours, and then 100 mg/kg infused over 16 hours. Maximum dose is typically 300 mg/kg over 21 hours. Specific protocols may vary. * **Oral:** Load of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses. **Mucolytic:** * **Oral:** 200 mg to 400 mg twice daily or three times daily. * **Nebulization:** 1 to 10 mL of a 10% or 20% solution every 2 to 6 hours as needed. ## Pediatric Dosing **Acetaminophen Overdose:** * **Intravenous (IV):** Same protocol as adults: Load of 150 mg/kg infused over 1 hour, followed by 50 mg/kg infused over 4 hours, and then 100 mg/kg infused over 16 hours. * **Oral:** Same protocol as adults: Load of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses. **Mucolytic:** * **Oral:** 50 mg/kg to 100 mg/kg per dose every 3 to 4 hours. Maximum 800 mg/day. * **Nebulization:** 1 to 10 mL of a 10% or 20% solution every 2 to 6 hours as needed. ## Dose Adjustments No dose adjustments are typically required for renal or hepatic impairment for the mucolytic indication. For acetaminophen overdose, dosing is based on weight and not typically adjusted for organ dysfunction unless there are specific concerns about drug clearance. ## Contraindications * Hypersensitivity to acetylcysteine. * Asthma (relative contraindication for nebulized form due to potential bronchospasm). ## Adverse Effects * **Oral:** Nausea, vomiting, diarrhea, stomatitis. * **Intravenous:** Anaphylactoid reactions (hypotension, bronchospasm, rash, angioedema), urticaria, pruritus. * **Nebulization:** Bronchospasm, rhinorrhea, nausea. ## Key Drug Interactions * **Activated Charcoal:** May adsorb oral acetylcysteine, reducing its absorption. Administer acetylcysteine at least 1 hour after activated charcoal. * **Nitroglycerin:** Concomitant use may potentiate hypotensive effects. ## Monitoring * **Acetaminophen Overdose:** Serial acetaminophen and ALT levels, prothrombin time, INR, lactate. Monitor for signs of hepatotoxicity. * **Mucolytic:** Monitor respiratory status and sputum viscosity. Assess for adverse effects. ## Clinical Pearls * The odor of acetylcysteine can be strong and may cause nausea. Consider antiemetics if needed. * For IV acetylcysteine, a continuous infusion is preferred for anaphylactoid reactions. * The effectiveness of acetylcysteine for acetaminophen overdose is time-dependent; prompt administration is crucial. * Nebulized acetylcysteine may cause bronchospasm in susceptible individuals; co-administration of a bronchodilator may be beneficial. *** *Disclaimer: This information is intended for clinical pharmacists and healthcare professionals. It is essential to consult the most current prescribing information and local protocols for definitive guidance.*