Acetyl%252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520cysteine

# Acetylcysteine ## Overview Acetylcysteine (N-acetylcysteine, NAC) is a mucolytic agent and an antidote for acetaminophen overdose. It also has antioxidant properties. ## Primary Indications * **Acetaminophen overdose:** To prevent or reduce liver toxicity. * **Mucolytic:** To thin and loosen mucus in specific respiratory conditions (e.g., COPD, cystic fibrosis). ## Adult Dosing **Acetaminophen Overdose:** Intravenous (IV) administration is preferred for acute overdose. The standard protocol involves an initial loading dose followed by subsequent infusions. * **Loading Dose:** 150 mg/kg IV over 60 minutes. * **Second Infusion:** 50 mg/kg IV over 60 minutes. * **Third Infusion:** 100 mg/kg IV infused over 16 hours. (Total duration of 21 hours). Maximum IV dose for overdose is generally not capped per infusion but is determined by body weight and protocol. **Mucolytic:** * **Oral:** 200 mg to 400 mg two to four times daily. Maximum 1200 mg daily. * **Inhaled:** 1 to 10 mL of a 10% or 20% solution every 2 to 6 hours as needed. Dosing is often guided by local protocol. Higher concentrations (20%) may cause bronchospasm in some patients. * **Intravenous (non-overdose):** Less common, typically used in severe respiratory conditions, dosing varies significantly by indication and is often institution-specific. ## Pediatric Dosing **Acetaminophen Overdose:** Dosing is the same as adults based on weight, but may require dilution for smaller patients to achieve accurate infusion rates. * **Loading Dose:** 150 mg/kg IV over 60 minutes. * **Second Infusion:** 50 mg/kg IV over 60 minutes. * **Third Infusion:** 100 mg/kg IV infused over 16 hours. **Mucolytic:** * **Oral:** 10 mg/kg to 30 mg/kg per dose, two to four times daily. Maximum 1200 mg daily. * **Inhaled:** 1 mL of a 10% or 20% solution (mixed with equal parts sterile saline or water for inhalation if using 20% solution), every 2 to 6 hours as needed. Dosing is often guided by local protocol. ## Dose Adjustments No specific dose adjustments are typically required for renal or hepatic impairment for the acetaminophen overdose protocol, as the goal is to saturate liver pathways. For mucolytic use, adjust based on patient tolerance and response. ## Contraindications * Hypersensitivity to acetylcysteine or any component of the formulation. * Acute bronchospasm (for inhaled acetylcysteine). ## Adverse Effects * **Anaphylactoid reactions:** Most common with IV administration (urticaria, rash, pruritus, bronchospasm, angioedema, hypotension). These are usually non-allergic and related to the rate of infusion. * **Nausea and vomiting:** Common with oral and IV administration. * **Bronchospasm:** More common with inhaled acetylcysteine, especially in patients with asthma. * **Rhinorrhea, stomatitis, drowsiness, fever.** ## Key Drug Interactions * **Activated charcoal:** May bind to orally administered acetylcysteine, reducing its absorption. Separate administration by at least 1 hour. * **Nitroglycerin:** May potentiate the vasodilatory effect and potentially lead to hypotension. Reduce nitroglycerin dose if coadministered. ## Monitoring * **Acetaminophen Overdose:** * Acetaminophen serum levels (peak and 4-hour post-ingestion levels are crucial for determining need for NAC). * Liver function tests (ALT, AST, bilirubin, INR) to assess for hepatotoxicity. * Renal function. * Blood glucose. * Vital signs, especially during IV infusion due to risk of anaphylactoid reactions. * **Mucolytic:** * Respiratory status (rate, depth, presence of wheezing/bronchospasm). * Sputum characteristics. ## Clinical Pearls * For acetaminophen overdose, prompt initiation of acetylcysteine is critical, ideally within 8 hours of ingestion. * IV acetylcysteine requires careful monitoring for anaphylactoid reactions, which can often be managed by slowing the infusion rate. * Oral acetylcysteine has a characteristic sulfurous odor that patients may find unpleasant. * For inhaled acetylcysteine, consider co-administering a bronchodilator prior to acetylcysteine if bronchospasm is a concern. *** **Disclaimer:** This information is for educational purposes only and does not constitute medical advice. Always consult the most current prescribing information and relevant clinical guidelines from a qualified healthcare professional before making any decisions about drug therapy.