Acetyl%25252525252525252525252525252525252525252525252525252525252525252525252520cysteine

# Acetylcysteine ## Overview Acetylcysteine (N-acetylcysteine) is a mucolytic agent and an antidote for acetaminophen overdose. It works by breaking disulfide bonds in mucus, reducing its viscosity, and by replenishing glutathione stores depleted by toxic acetaminophen metabolites. ## Primary Indications * **Acetaminophen overdose:** Treatment within 8-10 hours of ingestion. * **Mucolytic:** Adjunct in conditions with thick bronchial secretions (e.g., COPD, bronchitis, pneumonia, cystic fibrosis). ## Adult Dosing **Acetaminophen Overdose:** * **Intravenous (IV):** A common protocol involves a loading dose of 150 mg/kg over 1 hour, followed by a maintenance infusion. An initial maintenance dose of 12.5 mg/kg/hour for 4 hours, then 6.25 mg/kg/hour for the next 16 hours. Total duration of 21 hours. *Specific IV protocols can vary significantly by institution and may involve higher initial doses or different infusion rates. Consult local guidelines.* * **Oral:** Load with 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses (total 710 mg/kg over 72 hours). Less preferred due to gastrointestinal intolerance and emesis. **Mucolytic:** * **Oral:** 200 mg to 400 mg twice daily or three times daily. * **Nebulized:** 1% to 20% solution, 1 to 10 mL every 2 to 6 hours as needed. ## Pediatric Dosing **Acetaminophen Overdose:** * **Intravenous (IV):** Similar protocol to adults based on weight: 150 mg/kg over 1 hour, followed by 12.5 mg/kg/hour for 4 hours, then 6.25 mg/kg/hour for the remaining 16 hours. *Confirm age/weight-based adjustments and local protocols.* * **Oral:** Load with 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses. *Consider reduced doses for neonates/infants and emesis risk.* **Mucolytic:** * **Oral:** 50 mg to 100 mg twice or three times daily. * **Nebulized:** 10% solution, 1 to 2 mL every 2 to 6 hours. Higher concentrations (up to 20%) may be used in older children. ## Dose Adjustments * **Renal/Hepatic Impairment:** No specific dose adjustments are typically required for the antidote indication due to the urgent nature. For mucolytic use, caution may be advised, but evidence is limited. ## Contraindications * Hypersensitivity to acetylcysteine. * Active bronchospasm (for nebulized use). ## Adverse Effects * **Anaphylactoid reactions:** Most common with IV administration (rash, pruritus, angioedema, bronchospasm, dyspnea, hypotension). These are generally not true anaphylaxis and may be managed with slowing infusion rate or pre-treatment. * **Gastrointestinal:** Nausea, vomiting, diarrhea (especially with oral administration). * **Respiratory:** Bronchospasm (with nebulized form), rhinorrhea. * **Local:** Urticaria, injection site pain/erythema. ## Key Drug Interactions * **Activated Charcoal:** Can adsorb oral acetylcysteine, reducing its absorption. Administer charcoal at least 1 hour *before* or 1 hour *after* oral acetylcysteine. * **Nitroglycerin:** May potentiate hypotensive effect. ## Monitoring * **Acetaminophen Levels:** Monitor serum acetaminophen levels to assess treatment efficacy and duration. * **Liver Function Tests (LFTs):** Monitor liver enzymes (AST, ALT) and bilirubin, especially in patients with elevated baseline levels or prolonged treatment. * **Renal Function:** Monitor electrolytes and renal function. * **Clinical Status:** Monitor for signs of anaphylactoid reactions, respiratory distress, and gastrointestinal tolerance. ## Clinical Pearls * IV acetylcysteine is the preferred route for acetaminophen overdose due to better tolerability and consistent absorption. * Anaphylactoid reactions are common with IV acetylcysteine but are typically manageable and do not necessitate discontinuation unless severe. * Nausea and vomiting with oral acetylcysteine can be significant; antiemetics may be considered. * For nebulized use, consider a bronchodilator before acetylcysteine if bronchospasm is a concern. * The smell of acetylcysteine is characteristic of rotten eggs; reassure patients and staff. *** **Disclaimer:** This information is intended for healthcare professionals. Always verify current prescribing information and consult with your institution's protocols before making treatment decisions.