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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucoproteins, reducing viscosity. It also serves as an antidote for acetaminophen overdose by replenishing glutathione stores.
## Primary Indications
* **Acetaminophen overdose:** To prevent or reduce liver toxicity.
* **Mucolytic:** To thin respiratory secretions in conditions like cystic fibrosis, COPD, and pneumonia.
## Adult Dosing
### Acetaminophen Overdose
* **Oral:** Typically a loading dose of 140 mg/kg followed by 70 mg/kg every 4 hours for 17 doses. Maximum single oral dose is 1000 mg.
* **Intravenous (IV):** Commonly initiated with a loading dose of 150 mg/kg over 1 hour, followed by 12.5 mg/kg/hour for 4 hours, then 6.25 mg/kg/hour for up to 72 hours. Specific IV protocols can vary; consult local guidelines.
### Mucolytic
* **Nebulized:** 1 to 10 mL of 10% or 20% solution every 2 to 6 hours as needed. May also be administered as 3 to 5 mL of 20% solution or 6 to 10 mL of 10% solution every 2 to 6 hours.
* **Oral:** 200 mg to 400 mg two to four times daily.
## Pediatric Dosing
### Acetaminophen Overdose
* **Oral:** Dosing is the same as adults: 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses.
* **Intravenous (IV):** Pediatric IV protocols follow adult regimens, but actual doses are weight-based. Consult local guidelines.
### Mucolytic
* **Nebulized:**
* 1 month to 6 years: 1 to 2 mL of 20% solution or 2 to 5 mL of 10% solution every 2 to 6 hours.
* 6 years and older: 1 to 10 mL of 10% or 20% solution every 2 to 6 hours as needed. May also be administered as 3 to 5 mL of 20% solution or 6 to 10 mL of 10% solution every 2 to 6 hours.
## Dose Adjustments
No dose adjustments are typically required for hepatic or renal impairment, although caution is advised in severe cases.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
## Adverse Effects
* **Common:** Nausea, vomiting, stomatitis, rash, urticaria, pruritus.
* **Less Common:** Bronchospasm, dyspnea, fever, headache.
* **IV:** Anaphylactoid reactions (hypotension, bronchospasm, angioedema) can occur, especially with rapid infusion.
## Key Drug Interactions
* **Activated Charcoal:** Can bind to oral acetylcysteine, reducing its absorption. Administer acetylcysteine at least 1 hour after activated charcoal.
* **Nitroglycerin:** May potentiate the hypotensive effect of nitroglycerin.
## Monitoring
* **Acetaminophen Overdose:** Serial serum acetaminophen levels, liver function tests (AST, ALT, bilirubin, INR), and clinical signs of hepatotoxicity.
* **Mucolytic:** Respiratory status, sputum production, and frequency/severity of exacerbations.
## Clinical Pearls
* The smell of acetylcysteine is strong and often described as sulfurous; this is normal.
* For IV administration in acetaminophen overdose, continuous infusion is generally preferred over bolus doses to minimize anaphylactoid reactions.
* Always confirm the acetaminophen level and time of ingestion before discontinuing treatment for overdose.
* Dilute nebulized acetylcysteine with sterile water or normal saline if concentration is too high or causes irritation.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines for definitive guidance.*
