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# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent that decreases the viscosity of respiratory secretions. It is also an antidote for acetaminophen overdose. ## Primary Indications * **Acetaminophen Overdose:** To prevent or reduce liver toxicity. * **Mucolytic:** To thin and loosen mucus in patients with chronic bronchitis, emphysema, cystic fibrosis, or other bronchopulmonary diseases. ## Adult Dosing ### Acetaminophen Overdose * **Oral:** * **Loading Dose:** 140 mg/kg. * **Maintenance Dose:** 70 mg/kg every 4 hours for 17 doses (total of 72 hours). * **Intravenous (IV):** * **Loading Dose:** 150 mg/kg infused over 60 minutes. * **Second Infusion:** 50 mg/kg infused over 4 hours. * **Third Infusion:** 100 mg/kg infused over 16 hours. * *Note: IV protocols may vary; confirm local guidelines. Maximum infusion rates are crucial to avoid anaphylactoid reactions.* ### Mucolytic * **Nebulization:** 20% solution: 6-10 mL every 3-4 hours. 10% solution: 10-20 mL every 3-4 hours. * **Oral (effervescent tablets):** 200 mg twice daily or 200 mg three times daily. ## Pediatric Dosing ### Acetaminophen Overdose * **Oral and Intravenous (IV):** Dosing is the same as adults (140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses orally; or 150 mg/kg over 60 min, 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours IV). * *Note: IV protocols may vary; confirm local guidelines. Monitor for anaphylactoid reactions.* ### Mucolytic * **Nebulization:** * **Children < 6 years:** 10% solution: 1-2 mL every 2-6 hours. * **Children ≥ 6 years:** 10% solution: 5-10 mL every 3-4 hours; or 20% solution: 3-5 mL every 3-4 hours. * **Oral (effervescent tablets):** Typically not recommended for children under 2 years. Dosing for older children should be guided by product labeling or physician. ## Dose Adjustments * **Renal or Hepatic Impairment:** No specific dose adjustments are typically required for the mucolytic indication. For acetaminophen overdose, continued vigilance for toxicity is essential regardless of hepatic function. ## Contraindications * Known hypersensitivity to acetylcysteine. ## Adverse Effects * **Most Common:** Nausea, vomiting, stomatitis (oral use); bronchospasm, urticaria, angioedema, pruritus, rash, rhinorrhea, drowsiness (nebulized use). * **Anaphylactoid Reactions:** More common with IV administration, particularly during rapid infusion. Symptoms include bronchospasm, flushing, angioedema, urticaria, hypotension, and tachycardia. ## Key Drug Interactions * **Activated Charcoal:** May adsorb oral acetylcysteine, reducing its effectiveness in acetaminophen overdose. If co-administered, consider administering acetylcysteine 1 hour after charcoal. * **Nitroglycerin:** Increased hypotensive effect. ## Monitoring * **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests (AST, ALT, bilirubin, INR), blood glucose, and renal function. Clinical signs of hepatotoxicity. * **Mucolytic:** Respiratory status, sputum production, and airway patency. ## Clinical Pearls * The odor of acetylcysteine is unpleasant and may cause nausea/vomiting. * For IV administration in acetaminophen overdose, consider pre-treatment with an antihistamine and/or bronchodilator to mitigate anaphylactoid reactions. * Ensure adequate hydration when used as a mucolytic. * IV acetylcysteine should be administered through a central venous catheter if possible to minimize phlebitis. *** Please verify current prescribing information and consult with a healthcare provider for any specific patient care decisions.