Acetyl%2525252525252520cysteine

# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent and the specific antidote for acetaminophen (paracetamol) toxicity. It acts as a glutathione precursor, supporting hepatic detoxification of the toxic metabolite NAPQI. ## Primary Indications * **Acetaminophen overdose:** Treatment of acute ingestion or chronic/repeated supratherapeutic ingestion. * **Mucolytic therapy:** Adjunct treatment for abnormal, viscid, or inspissated mucous secretions (e.g., COPD, cystic fibrosis). * **Contrast-induced nephropathy (GIN) prophylaxis:** Efficacy is controversial and not consistently supported by clinical guidelines. ## Adult Dosing * **Acetaminophen Overdose (IV - Acetadote protocol):** * Loading: 150 mg/kg over 60 minutes. * Second dose: 50 mg/kg over 4 hours. * Maintenance: 100 mg/kg over 16 hours. * *Note: Protocol duration may be extended based on serum acetaminophen levels and ALT.* * **Mucolytic (Inhalation):** 1–10 mL of 20% solution or 2–20 mL of 10% solution via nebulizer every 4–6 hours. ## Pediatric Dosing * **Acetaminophen Overdose (IV):** Same weight-based regimen as adults (150 mg/kg loading, 50 mg/kg secondary, 100 mg/kg maintenance). Use standardized hospital protocols for dilution, as pediatric fluid balance is critical. * **Mucolytic (Inhalation):** 3–5 mL of 20% solution or 6–10 mL of 10% solution via nebulizer every 6–8 hours. ## Dose Adjustments * **Hepatic impairment:** No standard dosage adjustment for acetaminophen toxicity; however, adjust fluid volume if the patient is volume-restricted. * **Renal impairment:** No standard dosage adjustment; monitor for fluid overload. ## Contraindications * Hypersensitivity to acetylcysteine or any component of the formulation. * Oral/IV administration is generally safe; there are no absolute contraindications for the antidote in toxic ingestion, as the benefits of treating liver failure outweigh potential allergic reactions. ## Adverse Effects * **IV/Systemic:** Anaphylactoid reactions (flushing, urticaria, angioedema, bronchospasm, hypotension), especially during the loading dose. * **Inhalation:** Bronchospasm (pre-treat with short-acting beta-agonist), stomatitis, rhinorrhea, nausea, and vomiting. * **Odor:** Distinctive sulfur/rotten-egg odor is common and usually benign. ## Key Drug Interactions * **Activated Charcoal:** May adsorb acetylcysteine. Administer charcoal first, then acetylcysteine. If charcoal is administered, increase acetylcysteine dose or latency if appropriate per local poison control guidelines. * **Nitroglycerin:** Avoid concurrent use (or use with extreme caution) due to potential for severe hypotension and headache. ## Monitoring * **Acetaminophen Toxicity:** Serum acetaminophen levels (Rumack-Matthew nomogram), ALT/AST, INR, creatinine, and electrolytes. * **Systemic Administration:** Monitor vital signs closely during the loading dose for anaphylactoid reactions. * **Respiratory:** Monitor pulmonary status/cough effectiveness in patients receiving nebulized therapy. ## Clinical Pearls * **Anaphylactoid Reaction Management:** If a reaction occurs during IV infusion, stop infusion, administer antihistamines (e.g., diphenhydramine), and consider restarting at a slower rate once symptoms resolve. * **Route Preference:** IV administration is preferred for acetaminophen toxicity to avoid nausea/vomiting associated with oral administration, which can disrupt the loading dose delivery. * **Formulation:** Ensure the correct concentration (10% vs 20%) is used, especially for nebulized preparations. *** **Educational Disclaimer:** This information is for educational purposes only. Clinical protocols for acetaminophen toxicity vary by institution and poison control centers. Always verify dosing, dilution, and administration guidelines through current prescribing information or your local institutional pharmacy department before prescribing or administering medication.