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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucoproteins, reducing mucus viscosity. It is also an antidote for acetaminophen overdose by replenishing glutathione stores.
## Primary Indications
* Acetaminophen overdose
* Mucolytic agent for respiratory conditions (e.g., cystic fibrosis, chronic bronchitis, pneumonia, tracheostomy care)
## Adult Dosing
**Acetaminophen Overdose:**
* **Intravenous (IV):** Loading dose of 150 mg/kg infused over 1 hour, followed by 12.5 mg/kg/hour for 4 hours, then 6.25 mg/kg/hour for 16 hours. Total duration: 21 hours. Maximum dose depends on body weight and concentration of available preparation.
* **Oral:** 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses.
**Mucolytic:**
* **Nebulized:** 10% solution: 3-5 mL every 6-8 hours. 20% solution: 1-2 mL every 6-8 hours.
* **Oral:** 200 mg to 400 mg two to three times daily.
* **Intravenous (IV):** Not standard for mucolytic indications; used primarily for acetaminophen toxicity.
## Pediatric Dosing
**Acetaminophen Overdose:**
* **Intravenous (IV):** Same protocol as adults (150 mg/kg IV over 1 hour, then 12.5 mg/kg/hour for 4 hours, then 6.25 mg/kg/hour for 16 hours).
* **Oral:** Same protocol as adults (140 mg/kg PO every 4 hours for 17 doses).
**Mucolytic:**
* **Nebulized:** 10% solution: 1-2 mL every 6-8 hours. 20% solution: 1 mL every 6-8 hours. Dosing may vary based on age and severity; consult local protocol.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment for the antidote indication, though caution is advised in severe cases. For mucolytic use, dose adjustments are based on patient tolerance and response.
## Contraindications
Hypersensitivity to acetylcysteine. Use with caution in patients with asthma due to potential for bronchospasm with nebulized formulations.
## Adverse Effects
* **IV:** Anaphylactoid reactions (rash, pruritus, urticaria, angioedema, bronchospasm, dyspnea), hypotension, tachycardia. Nausea and vomiting can occur.
* **Nebulized:** Bronchospasm, stomatitis, nausea, vomiting, rhinorrhea.
* **Oral:** Nausea, vomiting, diarrhea, abdominal pain.
## Key Drug Interactions
* Activated charcoal may bind oral acetylcysteine, reducing absorption. Administer charcoal at least 1 hour before or 1 hour after oral acetylcysteine.
* Nitroglycerin may increase acetylcysteine levels and potentiate hypotension.
## Monitoring
* **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests (AST, ALT, bilirubin, INR), glucose, electrolytes, renal function, clinical status (mental status, respiratory status).
* **Mucolytic:** Respiratory status, lung sounds, sputum production, signs of bronchospasm.
## Clinical Pearls
* For IV administration in acetaminophen overdose, it is crucial to use the correct protocol. The loading dose should be infused rapidly, while subsequent infusions are at a slower rate.
* Dilute IV acetylcysteine to prevent adverse infusion reactions.
* Nebulized acetylcysteine may cause bronchospasm. Pretreatment with a bronchodilator is recommended, especially in patients with asthma.
* The smell of acetylcysteine is characteristically unpleasant (sulfurous).
* For acetaminophen overdose, treatment should be initiated empirically if acetaminophen levels are not immediately available and ingestion is suspected within the toxic range.
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*Disclaimer: This information is intended for healthcare professionals. Always verify current prescribing information and consult with a pharmacist or physician for individual patient management.*
