Acetyl%252525252525252525252525252525252525252525252525252520cysteine

# Acetylcysteine ## Overview Acetylcysteine (N-acetyl-L-cysteine) is a derivative of the amino acid cysteine. It functions clinically as a mucolytic agent via the disruption of disulfide bonds in mucus proteins and as a glutathione precursor used as an antidote for acetaminophen toxicity. ## Primary Indications * **Acetaminophen toxicity:** Prevention/treatment of hepatotoxicity. * **Mucolytic therapy:** Adjunctive therapy for abnormal, viscid, or inspissated mucous secretions (e.g., COPD, cystic fibrosis, pneumonia). * **Contrast-induced nephropathy:** Prevention (efficacy is controversial). ## Adult Dosing * **Acetaminophen Toxicity:** * **IV (Acetadote):** 3-bag protocol: 150 mg/kg over 60 min, then 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours. * **Oral:** 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 additional doses. * **Mucolytic (Inhalation):** 1–10 mL of 20% solution or 2–20 mL of 10% solution via nebulizer every 2–6 hours. * **Contrast Nephropathy (Oral):** 600–1200 mg BID for 2 days. ## Pediatric Dosing * **Acetaminophen Toxicity:** Same 3-bag IV protocol or 18-dose oral regimen as adults (weight-based dosing; verify specific protocol). * **Mucolytic (Inhalation):** 3–5 mL of 20% solution or 6–10 mL of 10% solution via nebulizer TID–QID. ## Dose Adjustments * **Renal/Hepatic:** No specific dose adjustments for mucolysis. In acetaminophen toxicity, dose adjustments may be required during the maintenance phase if patients experience severe adverse reactions (e.g., volume overload), but therapy should not be stopped until the full course is completed. ## Contraindications * Hypersensitivity to acetylcysteine or any component of the formulation. * Caution in patients with a history of asthma or bronchospasm due to risk of airway irritation. ## Adverse Effects * **IV:** Anaphylactoid reactions (flushing, pruritus, urticaria, angioedema), nausea, vomiting, and tachycardia. * **Inhalation:** Bronchospasm (most common), stomatitis, rhinorrhea, hemoptysis, and unpleasant odor (rotten egg smell due to sulfur content). ## Key Drug Interactions * **Activated Charcoal:** May bind acetylcysteine; oral acetylcysteine should be administered at least 1 hour after charcoal. * **Antibiotics:** Incompatible in the same nebulizer (e.g., tetracycline, erythromycin, amphotericin B); administer separately. ## Monitoring * **Acetaminophen Toxicity:** Serum acetaminophen levels, AST/ALT, prothrombin time (PT/INR), creatinine, and electrolytes. Monitor for anaphylactoid symptoms during IV infusion. * **Mucolytic:** Respiratory status, sputum production, and adventitious breath sounds. ## Clinical Pearls * **Anaphylactoid Reaction Management:** If a reaction occurs during IV administration, interrupt the infusion, administer antihistamines (e.g., diphenhydramine), and restart at a slower rate if the reaction is mild. * **IV Administration:** Ensure correct dilution using D5W (not Normal Saline unless stipulated by local protocol). * **Note on Dosing:** Dosing for acetaminophen toxicity can vary significantly by institution and severity of presentation (e.g., Rumack-Matthew nomogram versus empiric treatment). Always verify with local hospital protocols or Poison Control. *** *Disclaimer: This information is for educational purposes and does not constitute medical advice. Clinicians must verify all doses, indications, and contraindications against current institutional guidelines, local pharmacy protocols, and official manufacturer prescribing information before administration.*