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# Acetylcysteine ## Overview Acetylcysteine is an antidote for acetaminophen overdose and a mucolytic agent. ## Primary Indications * **Acetaminophen overdose:** To prevent or reduce liver toxicity. * **Mucolytic:** To thin and loosen mucus in respiratory conditions such as COPD, cystic fibrosis, and pneumonia. ## Adult Dosing * **Acetaminophen Overdose (Oral/IV):** * **Loading Dose:** 150 mg/kg (IV) or 140 mg/kg (oral) as a single dose. * **Subsequent Doses (IV):** 50 mg/kg every 4 hours for 17 doses (total of 18 doses over 72 hours). * **Subsequent Doses (Oral):** 70 mg/kg every 4 hours for 17 doses (total of 18 doses over 72 hours). * **IV Maximum:** Typically, a maximum infusion rate of 15 g/hour is recommended after the initial bolus, but specific protocol may vary. * **Oral Maximum:** Not to exceed 15 grams in 24 hours. * **Mucolytic (Nebulized):** * 3-5 mL of 10% or 20% solution every 2-6 hours as needed. ## Pediatric Dosing * **Acetaminophen Overdose (Oral/IV):** Dosing is based on weight, following the same regimen as adults (150 mg/kg loading dose followed by 70 mg/kg every 4 hours orally, or 50 mg/kg every 4 hours IV, for 17 subsequent doses). * **Mucolytic (Nebulized):** * 1-5 mL of 10% or 20% solution every 2-6 hours as needed. Lower concentrations may be used for infants. ## Dose Adjustments No specific dose adjustments are typically required for renal or hepatic impairment for the acetaminophen overdose protocol, though caution is advised due to potential accumulation of metabolites. ## Contraindications * Hypersensitivity to acetylcysteine. * Acute bronchospasm (for nebulized formulation). ## Adverse Effects * **Common:** Nausea, vomiting, rash, pruritus, fever, stomatitis (oral/IV). Bronchospasm, rhinorrhea, drowsiness (nebulized). * **Serious:** Anaphylactoid reactions, bronchospasm, angioedema. ## Key Drug Interactions * **Activated charcoal:** May bind to oral acetylcysteine, reducing its absorption. Administer oral acetylcysteine at least 1 hour after activated charcoal. * **Nitroglycerin:** May potentiate vasodilation and hypotension. ## Monitoring * **Acetaminophen Overdose:** Liver function tests (AST, ALT, bilirubin, INR), serum creatinine, glucose, electrolytes, and acetaminophen levels. Clinical assessment for signs of anaphylaxis. * **Mucolytic:** Pulmonary status, sputum production, and signs of bronchospasm. ## Clinical Pearls * Intravenous acetylcysteine is preferred over oral due to better palatability and absorption, especially in patients with persistent vomiting. * Protocols for IV acetylcysteine in acetaminophen overdose can vary, particularly regarding the final doses and duration, based on local institutional guidelines and patient response. Always confirm the specific protocol. * For nebulized acetylcysteine, a faint sulfurous odor is expected and does not indicate degradation. * Anaphylactoid reactions to IV acetylcysteine are common and usually mild, but can be severe. Pre-treatment with an antihistamine may be considered. *** *This information is intended for clinical use and does not replace comprehensive drug information resources. Always verify current prescribing information and local protocols before administering medications.*