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# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent that works by breaking disulfide bonds in mucus, reducing its viscosity. It also acts as an antidote for acetaminophen overdose by replenishing glutathione stores. ## Primary Indications * Acetaminophen overdose (antidote) * Mucolytic for conditions with thick mucus (e.g., cystic fibrosis, COPD, pneumonia) ## Adult Dosing * **Acetaminophen Overdose:** * **Oral:** 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses. Maximum single dose typically 1 gram. * **Intravenous:** 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. * *Note: Specific IV protocols may vary; consult local guidelines.* * **Mucolytic:** * **Inhaled:** 10% solution 3-5 mL every 3-4 hours, or 20% solution 3-5 mL every 6-8 hours. * **Oral:** 200 mg twice daily to three times daily. ## Pediatric Dosing * **Acetaminophen Overdose:** Dosing is weight-based and generally follows adult protocols, adjusted for weight. Consult specific pediatric protocols. * **Mucolytic:** * **Inhaled:** 10% solution 1-2 mL or 20% solution 1-2 mL TID-QID. ## Dose Adjustments * No specific dose adjustments are typically required for renal or hepatic impairment, though caution may be advised in severe cases. ## Contraindications * Hypersensitivity to acetylcysteine or components. * Active gastrointestinal bleeding (oral formulations). ## Adverse Effects * **Inhaled:** Bronchospasm, bronchoconstriction, stomatitis, rhinorrhea, nausea. * **Intravenous:** Anaphylactoid reactions (hypotension, bronchospasm, rash, angioedema), nausea, vomiting, fever. * **Oral:** Nausea, vomiting, diarrhea, rash. ## Key Drug Interactions * Activated charcoal (oral) can reduce the absorption of oral acetylcysteine in overdose situations. * Concurrent use with nitroglycerin may lead to additive hypotension. ## Monitoring * **Acetaminophen Overdose:** * Acetaminophen and its metabolite (NAPQI) levels. * Liver function tests (AST, ALT, INR, bilirubin). * Renal function. * Prothrombin time/INR. * **Mucolytic:** * Respiratory status, mucus production, and sputum viscosity. * Bronchospasm. ## Clinical Pearls * Intravenous acetylcysteine for acetaminophen overdose can cause anaphylactoid reactions; slow infusion rate and have emergency equipment readily available. * When used as a mucolytic, hydration is important to facilitate clearance. * The odor of acetylcysteine is strong (sulfurous) and may be unpleasant. *** **Disclaimer:** This information is intended for healthcare professionals. Always consult the current official prescribing information and local protocols for complete and up-to-date guidance.