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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:** Treatment to prevent liver toxicity.
* **Mucolytic Agent:** To thin thick mucus in conditions like cystic fibrosis or chronic obstructive pulmonary disease (COPD).
## Adult Dosing
### Acetaminophen Overdose
* **Oral:** Loading dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses.
* **Intravenous (IV):** Protocols vary significantly; common regimens include a 3-bag (or 2-bag) infusion. A typical 3-bag regimen:
* **Bolus:** 150 mg/kg IV over 1 hour.
* **Infusion 1:** 12.5% solution at 12.5 mg/kg/hour for 4 hours.
* **Infusion 2:** 12.5% solution at 6.25 mg/kg/hour for 16 hours.
* **Total duration:** 21 hours.
* **Maximum infusion rates:** Consult local protocol; generally aim to not exceed 15 g/hr.
* **Nebulized:** 20% solution, 3-5 mL every 3-4 hours, or 10% solution, 6-10 mL every 3-4 hours. May be alternated with bronchodilators.
### Mucolytic Agent
* **Oral:** 200 mg twice daily to 600 mg three times daily.
* **Nebulized:** 20% solution, 3-5 mL every 3-4 hours, or 10% solution, 6-10 mL every 3-4 hours.
## Pediatric Dosing
### Acetaminophen Overdose
* **Oral:** Same as adult: 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses.
* **Intravenous (IV):** Same as adult IV regimens, adjusted for weight. Ensure appropriate dilution for pediatric patients. Consult local protocol.
* **Nebulized:**
* **< 1 year:** 10% solution, 1 mL every 2-6 hours.
* **1-12 years:** 10% solution, 1-2 mL every 2-6 hours; or 20% solution, 1 mL every 2-6 hours.
* **> 12 years:** Same as adult nebulized.
### Mucolytic Agent
* **Nebulized:** Dosing similar to adult nebulized, adjusted for weight and age as above for acetaminophen overdose.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, but caution may be warranted in severe cases.
## Contraindications
* Known hypersensitivity to acetylcysteine.
## Adverse Effects
* **IV:** Anaphylactoid reactions (most common and serious), rash, urticaria, angioedema, bronchospasm, dyspnea, hypotension. Nausea and vomiting are common.
* **Oral:** Nausea, vomiting, diarrhea, stomatitis.
* **Nebulized:** Bronchospasm (especially in asthmatics), rhinorrhea, nausea, vomiting.
## Key Drug Interactions
* **Activated Charcoal:** May bind acetylcysteine, reducing oral absorption. Administer charcoal at least 1 hour before or 1 hour after oral acetylcysteine.
* **Nitroglycerin:** Potential for additive hypotensive effects.
## Monitoring
* **Acetaminophen Overdose:**
* **Liver Function Tests (LFTs):** Baseline and serial LFTs (AST, ALT, bilirubin, INR, prothrombin time) to assess for hepatotoxicity.
* **Acetaminophen Levels:** To guide duration of therapy.
* **Renal and Electrolyte Panel:** Particularly if significant vomiting occurs.
* **Mucolytic Use:** Clinical response (ease of expectoration, improvement in lung function). Monitor for bronchospasm.
## Clinical Pearls
* IV acetylcysteine for acetaminophen overdose is most effective when initiated within 8 hours of ingestion.
* The smell of rotten eggs is characteristic and may cause nausea; pre-medication with an antiemetic may be considered for IV administration.
* Nebulized acetylcysteine can sometimes worsen bronchospasm; co-administration with a bronchodilator may be beneficial.
* Always confirm the concentration of the IV solution being prepared for infusion.
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*This information is for educational purposes only and does not substitute for professional medical advice. Always consult the current prescribing information and relevant guidelines for complete and up-to-date details before making any treatment decisions.*
