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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks down disulfide bonds in mucus, reducing its viscosity. It is also an antidote for acetaminophen overdose.
## Primary Indications
* **Acetaminophen Overdose:** To prevent or reduce liver damage following acetaminophen ingestion.
* **Mucolytic:** To thin mucus in respiratory conditions such as pneumonia, bronchitis, and cystic fibrosis.
## Adult Dosing
* **Acetaminophen Overdose:**
* **Loading Dose:** 150 mg/kg intravenously (IV) over 1 hour.
* **Second Dose:** 50 mg/kg IV over 16 hours (infused at 12.5 mg/kg/hr).
* **Third Dose (if needed):** 50 mg/kg IV over 16 hours (infused at 12.5 mg/kg/hr).
* *Maximum total dose is not typically specified, but considerations for hepatic capacity are made.*
* **Oral Protocol:** 140 mg/kg orally (PO) loading dose, followed by 70 mg/kg PO every 4 hours for 17 doses.
* **Mucolytic (Inhaled):** 3 mL of 10% or 20% solution nebulized every 2-6 hours. Higher doses may be used in severe cases per institutional protocol.
## Pediatric Dosing
* **Acetaminophen Overdose (IV):** Dosing is the same as adults (150 mg/kg IV loading, then 50 mg/kg IV over 16 hours).
* **Acetaminophen Overdose (Oral):** 140 mg/kg PO loading dose, followed by 70 mg/kg PO every 4 hours for 17 doses.
* **Mucolytic (Inhaled):** 1 mL of 10% or 20% solution nebulized every 2-6 hours.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is typically required, but caution is advised.
* **Hepatic Impairment:** For acetaminophen overdose, close monitoring for liver function is crucial; dose adjustments are not standard but treatment duration may be extended.
## Contraindications
* Hypersensitivity to acetylcysteine.
* Active hemorrhage (inhalation route).
## Adverse Effects
* **IV:** Anaphylactoid reactions (rash, pruritus, bronchospasm, angioedema), nausea, vomiting, flushing, urticaria.
* **Inhaled:** Bronchospasm, rhinorrhea, nausea, vomiting, stomatitis.
* **Oral:** Nausea, vomiting, diarrhea, stomatitis.
## Key Drug Interactions
* **Activated Charcoal:** May bind to oral acetylcysteine, reducing its absorption. Administer oral acetylcysteine at least 1 hour after activated charcoal.
* **Nitroglycerin:** May potentiate the hypotensive effect of nitroglycerin.
## Monitoring
* **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests (AST, ALT, bilirubin, PT/INR), glucose, electrolytes, renal function, and clinical status.
* **Mucolytic:** Respiratory status, sputum viscosity, and presence of bronchospasm.
## Clinical Pearls
* For IV acetylcysteine in acetaminophen overdose, rapid infusion can increase the risk of anaphylactoid reactions. Use dilute solutions and appropriate infusion rates.
* N-acetylcysteine has a characteristic sulfurous odor.
* Consider co-administration of bronchodilators with inhaled acetylcysteine if bronchospasm is a concern.
* For inhaled use, if bronchospasm occurs, discontinue therapy and administer a bronchodilator.
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**Disclaimer:** This information is intended for healthcare professionals and does not replace a thorough review of the current prescribing information, clinical guidelines, and institutional protocols. Always verify the most up-to-date drug information before administration.
