Acetyl%2525252525252525252525252525252525252525252525252520cysteine

# Acetylcysteine (N-acetylcysteine / NAC) ## Overview Acetylcysteine is a mucolytic agent and a precursor to glutathione. It acts by splitting disulfide bonds in mucoproteins (lowering viscosity) and by replenishing hepatic glutathione stores to detoxify the NAPQI metabolite following acetaminophen overdose. ## Primary Indications * **Acetaminophen toxicity:** Antidote for hepatotoxicity. * **Mucolytic therapy:** Adjunct for abnormal, viscid, or inspissated mucous secretions in bronchopulmonary disease. ## Adult Dosing * **Acetaminophen Overdose (IV Protocol - FDA Approved):** * Loading dose: 150 mg/kg infused over 60 minutes. * Second dose: 50 mg/kg infused over 4 hours. * Third dose: 100 mg/kg infused over 16 hours. * *Note: Total duration is 21 hours; infusion rates and protocols may vary based on institution-specific nomograms or severity.* * **Mucolytic (Inhalation):** 3–5 mL of 20% solution or 6–10 mL of 10% solution via nebulizer 3–4 times daily. ## Pediatric Dosing * **Acetaminophen Overdose (IV):** Same weight-based mg/kg dosing as adults (150/50/100). Use caution with fluid administration in small children (dilute in D5W or NS). * **Mucolytic (Inhalation):** 3–5 mL of 20% solution or 6–10 mL of 10% solution via nebulizer 3–4 times daily. ## Dose Adjustments * **Renal/Hepatic:** No standardized adjustment for mucolytic use. For acetaminophen overdose, continue infusion until labs normalize, regardless of initial impairment. * **Fluid restricted:** Concentration may be increased to reduce total volume infused, but extreme caution is required to prevent hyponatremia. ## Contraindications * Hypersensitivity to acetylcysteine or any component of the formulation. * Use caution in patients with asthma (may cause bronchospasm). ## Adverse Effects * **IV:** Anaphylactoid reactions (flushing, pruritus, wheezing, hypotension). Risk is dose-dependent and typically occurs during the initial loading dose. * **Inhalation:** Bronchospasm, nausea, vomiting, stomatitis, rhinorrhea, unpleasant odor (sulfur-like). ## Key Drug Interactions * **Activated Charcoal:** May adsorb acetylcysteine. Administer charcoal at least 1 hour before NAC, or if given concurrently, consider increasing NAC dose (local protocol may vary). * **Incompatible Drugs:** Physically incompatible in solution with certain antibiotics (e.g., tetracycline, erythromycin, amphotericin B); flush line between administrations. ## Monitoring * **Acetaminophen Overdose:** Serial AST/ALT, acetaminophen levels, PT/INR, serum creatinine, electrolytes, and arterial blood gas (if needed). * **Mucolytic:** Monitor respiratory effort, cough effectiveness, and lung sounds. Stop if bronchospasm occurs. ## Clinical Pearls * **Anaphylactoid Reaction Management:** If a reaction occurs (often cutaneous only), hold the infusion, administer antihistamines (e.g., diphenhydramine), and restart at a slower rate once symptoms resolve. * **Efficacy:** Acetaminophen NAC therapy is most effective if started within 8 hours of ingestion. * **Odor:** Warn patients that the medication has an unpleasant sulfurous odor, which is normal. *** **Educational Disclaimer:** This information is for educational purposes only. Always verify dosing, contraindications, and drug compatibility via current clinical institutional protocols, electronic health record databases, or official FDA prescribing information before administration.