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# Acetylcysteine
## Overview
Acetylcysteine (Mucomyst, Acetadote) is a mucolytic agent and an antidote for acetaminophen overdose.
## Primary Indications
* **Acetaminophen Overdose:** To prevent or reduce liver toxicity.
* **Mucolytic Agent:** To thin and loosen mucus in certain respiratory conditions (e.g., chronic bronchitis, emphysema, cystic fibrosis).
## Adult Dosing
* **Acetaminophen Overdose:**
* **Oral:** 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses (total of 72 hours). Maximum single dose generally not to exceed 200 mg/kg or 1000 mg.
* **Intravenous (IV):** A common regimen includes 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 16 hours (total of 21 hours). *Specific IV protocols can vary and should be followed per institutional guidelines.*
* **Mucolytic Agent:**
* **Inhaled:** 3 mL to 5 mL of a 10% or 20% solution via nebulizer every 3 to 4 times daily.
* **Intratracheal:** 1 mL to 2 mL of a 10% or 20% solution every 1 to 4 hours as needed.
## Pediatric Dosing
* **Acetaminophen Overdose:**
* **Oral:** Same as adult: 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses. *Use with caution in children < 6 years due to risk of vomiting. Consider IV route.*
* **Intravenous (IV):** Same as adult: 150 mg/kg loading dose, followed by 12.5 mg/kg/hour for 4 hours, then 6.25 mg/kg/hour for 16 hours. *Specific IV protocols can vary and should be followed per institutional guidelines.*
* **Mucolytic Agent:**
* **Inhaled:** 1 mL to 2 mL of a 10% or 20% solution via nebulizer every 3 to 4 times daily. *Dosing is often weight-based in infants, but not clearly established.*
## Dose Adjustments
No specific dose adjustments are typically required for hepatic or renal impairment, though caution is advised, especially in severe cases.
## Contraindications
* Hypersensitivity to acetylcysteine.
* Aspirin-induced asthma (for inhaled use, due to potential bronchospasm).
## Adverse Effects
* **Inhaled:** Bronchospasm, bronchoconstriction, stomatitis, nausea, vomiting, rhinorrhea.
* **IV:** Anaphylactoid reactions (ranging from rash, pruritus to bronchospasm and hypotension), angioedema, fever, chills, headache, tachycardia.
* **Oral:** Nausea, vomiting, diarrhea.
## Key Drug Interactions
* **Activated Charcoal:** Can adsorb acetylcysteine, reducing its efficacy in acetaminophen overdose if given concurrently. Separate administration by at least 1 hour.
* **Nitroglycerin:** May potentiate hypotensive effects.
## Monitoring
* **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests (AST, ALT, bilirubin, PT/INR), BUN, creatinine, glucose. Monitor for signs of anaphylaxis with IV administration.
* **Mucolytic Agent:** Respiratory status, presence of bronchospasm.
## Clinical Pearls
* The characteristic unpleasant odor of acetylcysteine may cause nausea and vomiting, especially with oral administration.
* Dilution of IV acetylcysteine may be necessary to reduce infusion-related reactions. Follow institutional protocols.
* When used for acetaminophen overdose, early administration is crucial for efficacy.
* IV acetylcysteine has largely replaced oral for acetaminophen overdose due to better palatability and potentially more consistent absorption, though oral is still effective if initiated promptly.
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*This information is intended for clinical professionals. Always verify current prescribing information with the manufacturer's package insert or other reliable sources before making clinical decisions.*
