Acetyl%2525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520cysteine

# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent and an antidote for acetaminophen overdose. It works by breaking disulfide bonds in mucus, reducing its viscosity, and also replenishes glutathione stores depleted by acetaminophen toxicity. ## Primary Indications * **Acetaminophen Overdose:** To prevent or reduce the severity of hepatotoxicity. * **Mucolytic:** To thin and loosen mucus in respiratory conditions such as chronic obstructive pulmonary disease (COPD), cystic fibrosis, and pneumonia. ## Adult Dosing **Acetaminophen Overdose:** The standard protocol involves an initial intravenous (IV) bolus dose followed by a continuous infusion. * **Standard 21-hour IV Protocol:** * **Loading Dose:** 150 mg/kg IV over 60 minutes. * **Second Infusion:** 50 mg/kg IV over the next 60 minutes (infused at 100 mL/hr if total volume is 3 L). * **Third Infusion:** 100 mg/kg IV infused over 16 hours (total infusion time 21 hours). * *Maximum infusion rate should not exceed 12.5 g/hr.* * **Alternative 12-hour IV Protocol:** (May be used in some centers, but consult local protocol) * **Loading Dose:** 150 mg/kg IV over 15 minutes. * **Subsequent Doses:** 12.5 mg/kg/hr IV for 11.25 hours. * *Maximum dose for loading is 150 mg/kg.* * *Maximum infusion rate should not exceed 12.5 g/hr.* **Mucolytic:** * **Inhalation:** 3 mL to 5 mL of a 10% or 20% solution administered via nebulizer every 4 to 12 hours. ## Pediatric Dosing **Acetaminophen Overdose:** Dosing is weight-based and follows the same IV protocols as adults. Ensure accurate weight measurement for appropriate dosing. * **Standard 21-hour IV Protocol:** * **Loading Dose:** 150 mg/kg IV over 60 minutes. * **Second Infusion:** 50 mg/kg IV over the next 60 minutes. * **Third Infusion:** 100 mg/kg IV infused over 16 hours. * **Alternative 12-hour IV Protocol:** (Consult local protocol) * **Loading Dose:** 150 mg/kg IV over 15 minutes. * **Subsequent Doses:** 12.5 mg/kg/hr IV for 11.25 hours. **Mucolytic:** * **Inhalation:** 1 mL to 2 mL of a 10% or 20% solution administered via nebulizer every 2 to 6 hours. (Dosing may vary based on age and severity). ## Dose Adjustments No specific dose adjustments are typically required for renal or hepatic impairment in the context of acetaminophen overdose, as the benefit of preventing liver failure outweighs the risks associated with impaired excretion. For mucolytic use, adjustments are usually based on clinical response and tolerability. ## Contraindications * Hypersensitivity to acetylcysteine or any component of the formulation. * Active gastrointestinal bleeding (for oral formulations, though IV is primarily used for overdose). ## Adverse Effects * **IV Administration (Acetaminophen Overdose):** Anaphylactoid reactions (rash, urticaria, pruritus, angioedema, bronchospasm, dyspnea), nausea, vomiting, flushing. These are often dose and rate-dependent. Hypotension can occur. * **Inhalation (Mucolytic):** Bronchospasm (especially in patients with asthma), nausea, vomiting, stomatitis, rhinorrhea. ## Key Drug Interactions * **Activated Charcoal:** May adsorb oral acetylcysteine if given concurrently, reducing its effectiveness. Separate administration. * **Nitroglycerin:** Potentiation of vasodilatory effects, leading to increased risk of hypotension and headache. ## Monitoring * **Acetaminophen Overdose:** * Serum acetaminophen levels and acetaminophen/sulfate ratio (to guide duration of therapy). * Liver function tests (AST, ALT, bilirubin, INR). * Renal function and electrolytes. * Vital signs, especially blood pressure and respiratory status, for anaphylactoid reactions. * **Mucolytic Use:** * Respiratory status, lung auscultation, and sputum production. * For bronchospasm, especially in susceptible patients. ## Clinical Pearls * For IV acetylcysteine in acetaminophen overdose, promptly initiate treatment. The antidote is most effective when given within 8 hours of ingestion. * Dilute IV acetylcysteine to a minimum concentration of 3 mg/mL to reduce the risk of fluid overload, especially in children. * Pretreatment with an H1 and H2 antagonist (e.g., diphenhydramine and famotidine) may be considered for patients at high risk of anaphylactoid reactions, though this is often a local protocol decision. * The smell of acetylcysteine is characteristically unpleasant (sulfurous), which can be a challenge for patient adherence with inhaled or oral formulations. *** *This information is intended for healthcare professionals. Always consult the current prescribing information and relevant clinical guidelines for complete and up-to-date details before making any treatment decisions.*