Acetyl%2525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520cysteine

# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent that also serves as an antidote for acetaminophen overdose. It works by breaking disulfide bonds in mucoproteins, decreasing mucus viscosity. As an antidote, it replenishes hepatic glutathione stores depleted by the toxic metabolite of acetaminophen (NAPQI). ## Primary Indications * **Acetaminophen Overdose:** To prevent or reduce liver damage. * **Mucolytic Agent:** To thin and loosen mucus in respiratory conditions such as cystic fibrosis, chronic bronchitis, and emphysema. ## Adult Dosing **Acetaminophen Overdose:** * **IV:** Typically a 3-bag, 72-hour protocol. * **Loading Dose:** 150 mg/kg infused over 60 minutes. * **Second Infusion:** 50 mg/kg infused over 60 minutes for the next 4 hours. * **Third Infusion:** 100 mg/kg infused over 16 hours. * *Maximum dose depends on protocol, but often around 300 mg/kg total.* * **PO:** Less common due to palatability and absorption issues. * **Loading Dose:** 140 mg/kg. * **Subsequent Doses:** 70 mg/kg every 4 hours for 17 doses (total of 18 doses). * *Maximum dose is typically 140 mg/kg for loading and 70 mg/kg for subsequent doses.* * **Intranasal:** Used in specific situations, often for nasal polyps or post-sinus surgery. Dosing varies; consult local protocol. **Mucolytic:** * **Inhaled:** 10% solution: 3-5 mL nebulized every 4-12 hours. 20% solution: 3-5 mL nebulized every 4-12 hours. * **Oral:** 200 mg to 400 mg twice daily or three times daily. ## Pediatric Dosing **Acetaminophen Overdose:** * **IV:** Same weight-based dosing as adults (150 mg/kg loading, 50 mg/kg x 4 hours, 100 mg/kg x 16 hours). Pediatric formulations may be required for accurate dosing in very small children. * **PO:** Same weight-based dosing as adults (140 mg/kg loading, 70 mg/kg every 4 hours for 17 doses). **Mucolytic:** * **Inhaled:** * < 1 year: 50 mg to 100 mg (using 10% solution) nebulized every 2-6 hours. * 1-2 years: 100 mg to 200 mg (using 10% solution) nebulized every 2-6 hours. * > 2 years: 200 mg to 300 mg (using 10% solution) nebulized every 2-6 hours. * **Oral:** Dosing is less established in pediatrics for mucolytic use. Consult local pediatric protocols. ## Dose Adjustments * **Renal Impairment:** No specific dose adjustment is usually recommended for IV or PO use in acetaminophen overdose. However, caution may be warranted in severe impairment. * **Hepatic Impairment:** No specific dose adjustment is usually recommended for IV or PO use in acetaminophen overdose. Close monitoring is crucial. * **Dialysis:** May require additional doses post-dialysis for acetaminophen overdose. Consult specific protocols. ## Contraindications * Hypersensitivity to acetylcysteine or any component of the formulation. * Active gastrointestinal bleeding (for oral formulations). ## Adverse Effects * **IV:** Anaphylactoid reactions (rash, urticaria, pruritus, bronchospasm, angioedema), flushing, tachycardia, hypotension, nausea, vomiting. * **Inhaled:** Bronchospasm (especially in asthmatics), nausea, vomiting, stomatitis, rhinorrhea, drowsiness. * **Oral:** Nausea, vomiting, diarrhea, stomatitis, rash. ## Key Drug Interactions * **Activated Charcoal:** May adsorb acetylcysteine, reducing its efficacy. If given, separate administration by at least 1 hour. * **Nitroglycerin:** May potentiate hypotensive effects. ## Monitoring * **Acetaminophen Overdose:** * **Acetaminophen levels:** To assess the need for continued treatment. * **Liver function tests (AST, ALT, bilirubin, INR):** To monitor for hepatotoxicity. * **Renal function tests (BUN, creatinine).** * **Electrolytes.** * **Vital signs and signs of anaphylactoid reaction.** * **Mucolytic:** * Pulmonary function tests. * Sputum characteristics (volume, viscosity). * Signs of bronchospasm. ## Clinical Pearls * The IV route for acetaminophen overdose is generally preferred for its more predictable absorption and lower incidence of emesis compared to oral. * For IV acetylcysteine, premedication with an H1 antihistamine may be considered to reduce the risk of anaphylactoid reactions. * N-acetylcysteine is a potent smell (sulfur odor), which can cause nausea and vomiting, especially with oral administration. Dilution or flavoring may improve palatability. * For inhaled acetylcysteine, co-administration with bronchodilators may be necessary to prevent or treat bronchospasm. * The efficacy of acetylcysteine for acetaminophen overdose is highest when initiated within 8-10 hours of ingestion. However, treatment should be initiated even if the patient presents later, as benefit may still be observed. *** **Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant guidelines for definitive guidance, as protocols and recommendations can change.