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# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent that works by decreasing the viscosity of respiratory secretions. It also serves as an antidote for acetaminophen overdose. ## Primary Indications * **Acetaminophen Overdose:** To prevent or reduce liver toxicity. * **Mucolytic:** To thin mucus in respiratory conditions such as bronchitis, emphysema, cystic fibrosis, and bronchiectasis. ## Adult Dosing **Acetaminophen Overdose:** * **Loading Dose:** 150 mg/kg IV infused over 1 hour. * **Second Dose:** 50 mg/kg IV infused over the next 16 hours. * **Third Dose (if needed):** 50 mg/kg IV infused over the next 16 hours. * A maximum total dose of 300 mg/kg over 21 hours is generally recommended. The exact infusion rate and total duration may vary based on local protocols and acetaminophen levels. **Mucolytic:** * **Oral/Intranasal:** 200 mg twice daily to 600 mg three times daily. * **Nebulization:** 1 to 10 mL of 10% or 20% solution (100 mg/mL or 200 mg/mL) every 2 to 6 hours. Dosing is often guided by patient response and tolerance, and specific protocols may exist. ## Pediatric Dosing **Acetaminophen Overdose:** * Dosing is the same as adult: 150 mg/kg IV over 1 hour, followed by 50 mg/kg IV over the next 16 hours. Dosing is weight-based. **Mucolytic:** * **Nebulization:** 1 to 10 mL of 10% or 20% solution (100 mg/mL or 200 mg/mL) every 2 to 6 hours. Dosing is often guided by patient response and tolerance. Specific protocols may exist. ## Dose Adjustments No specific dose adjustments are typically required for renal or hepatic impairment for the mucolytic indication. For acetaminophen overdose, the dosing is weight-based and aggressive management is prioritized. ## Contraindications Hypersensitivity to acetylcysteine or any component of the formulation. ## Adverse Effects * **Common:** Nausea, vomiting, stomatitis, rhinorrhea. * **Less Common (IV use):** Anaphylactoid reactions (rash, pruritus, bronchospasm, angioedema, hypotension), which can be severe. Dilution and slow infusion may reduce risk. * **Nebulized:** Bronchospasm (especially in asthmatics), airway irritation. ## Key Drug Interactions * **Activated Charcoal:** Can adsorb acetylcysteine, potentially reducing its efficacy in acetaminophen overdose. Separate administration by at least 1 hour. * **Nitroglycerin:** May potentiate the vasodilatory effect of nitroglycerin, leading to hypotension. Monitor blood pressure. ## Monitoring * **Acetaminophen Overdose:** Monitor acetaminophen and ALT/AST levels. Monitor for signs of hepatotoxicity. Monitor for anaphylactoid reactions during IV infusion. * **Mucolytic:** Monitor respiratory status, sputum viscosity, and patient tolerance (e.g., bronchospasm). ## Clinical Pearls * For IV use in acetaminophen overdose, it is crucial to initiate treatment as soon as possible, ideally within 8 hours of ingestion, for maximum benefit. * The odor of acetylcysteine is strong and sulfurous; this is normal. * When nebulizing, it may be advisable to pre-treat with a bronchodilator to minimize bronchospasm. *** *This information is intended for clinical professionals. Please verify current prescribing information from the manufacturer's package insert or other authoritative sources before initiating treatment.*