Acetyl%2525252525252525252525252525252520cysteine

# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent and the specific antidote for acetaminophen (paracetamol) toxicity. It restores hepatic glutathione, serving as a glutathione precursor to neutralize the toxic metabolite *N*-acetyl-*p*-benzoquinone imine (NAPQI). ## Primary Indications * Acetaminophen toxicity (oral and intravenous). * Mucolytic therapy in abnormal/viscid mucus secretions (inhalation). * Contrast-induced nephropathy prevention (efficacy remains controversial). ## Adult Dosing * **Acetaminophen Toxicity (IV Protocol - 20-21 hour regimen):** * Loading dose: 150 mg/kg in 200 mL D5W over 60 minutes. * Second dose: 50 mg/kg in 500 mL D5W over 4 hours. * Third dose: 100 mg/kg in 1000 mL D5W over 16 hours. * *Note: Always follow institutional protocol (e.g., Rumack-Matthew nomogram/SNAP protocol).* * **Mucolytic (Inhalation):** 1–10 mL of 20% solution or 2–20 mL of 10% solution via nebulizer every 2–6 hours. ## Pediatric Dosing * **Acetaminophen Toxicity:** Dosing is weight-based using the same IV protocol as adults. * Loading: 150 mg/kg. * Second dose: 50 mg/kg. * Third dose: 100 mg/kg. * *Adjustment for fluid status:* Volume of diluent must be reduced for fluid-restricted pediatric patients. Consult local pediatric protocols. ## Dose Adjustments * **Renal/Hepatic:** No specific dose adjustment defined for toxicity treatment, as it is life-saving; however, use caution with fluid overload in patients with cardiac or renal failure. * **Anaphylactoid Reactions:** If a reaction occurs during IV infusion, stop the infusion, administer antihistamines/corticosteroids, and restart at a slower rate if clinically appropriate. ## Contraindications * Hypersensitivity to acetylcysteine or any component of the formulation. * No absolute contraindications for the treatment of acetaminophen overdose, as the risk of hepatotoxicity outweighs the risk of anaphylactoid reaction. ## Adverse Effects * **Common:** Nausea, vomiting (oral), flushing, pruritus, rash. * **Serious:** Anaphylactoid reactions (hypotension, bronchospasm, angioedema), specifically with IV administration. * **Inhalation:** Bronchospasm (often requires concurrent use of a beta-agonist), stomatitis, rhinorrhea. ## Key Drug Interactions * **Nitroglycerin:** Acetylcysteine may enhance the vasodilatory and antiplatelet effects of nitroglycerin, potentially causing severe hypotension and headache. Monitor blood pressure closely. * **Inactivated/Live Vaccines:** Generally no significant interactions. ## Monitoring * **Acetaminophen Toxicity:** Serum acetaminophen levels, AST/ALT, bilirubin, INR, and creatinine. Monitor electrolytes and fluid status during long infusions. * **Anaphylactoid Reaction:** Monitor for rash, wheezing, or hypotension during the initial loading dose infusion. ## Clinical Pearls * **Oral vs. IV:** Oral administration is often limited by severe nausea/vomiting; IV is preferred for patients unable to tolerate oral intake or in cases of massive overdose. * **Odor:** The drug contains a sulfur group and has a strong "rotten egg" (sulfur) odor, which is normal. * **Timing:** Efficacy is highest when administered within 8 hours of acute acetaminophen ingestion. * **Nebulization:** Always administer a bronchodilator shortly before or with acetylcysteine to prevent medication-induced bronchospasm. *** **Disclaimer:** This information is for educational purposes only. Clinical protocols and safety data change frequently. Always verify specific dosing, safety, and compatibility information with your local hospital pharmacy, current clinical guidelines, and the manufacturer's official prescribing information before administration.