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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent and an antidote for acetaminophen overdose.
## Primary Indications
* **Acetaminophen Overdose:** To prevent or reduce liver damage.
* **Mucolytic:** To thin and loosen mucus in the airways, aiding expectoration in conditions like cystic fibrosis, COPD, and bronchitis.
## Adult Dosing
### Acetaminophen Overdose
* **Loading Dose:** 150 mg/kg IV infused over 1 hour.
* **Second Dose:** 50 mg/kg IV infused over 2 hours.
* **Subsequent Doses:** 100 mg/kg IV infused over 16 hours.
* **Maximum IV Dose:** Total dose not to exceed 300 mg/kg over a 24-hour period.
* **Oral Protocol:** Also available orally, with doses typically starting at 140 mg/kg followed by 70 mg/kg every 4 hours for 17 doses. Local protocols should be consulted for specific regimens.
### Mucolytic
* **Inhaled:** 3 mL of 10% or 20% solution via nebulizer every 2-6 hours as needed. Alternatively, 6-10 mL of 10% solution every 2-6 hours.
* **Intranasal:** 1-2 sprays of 20% solution into each nostril every 4 hours.
* **Oral:** 200 mg PO BID to TID.
## Pediatric Dosing
### Acetaminophen Overdose
* Dosing is the same as adults (150 mg/kg IV loading, then 50 mg/kg IV over 2 hours, then 100 mg/kg IV over 16 hours). Maximum dose calculations should be based on actual body weight.
* Oral dosing also follows adult recommendations (140 mg/kg PO followed by 70 mg/kg PO every 4 hours for 17 doses).
### Mucolytic
* **Inhaled:**
* **< 1 year:** 1-2 mL of 10% solution via nebulizer every 2-6 hours.
* **1-2 years:** 2-4 mL of 10% solution via nebulizer every 2-6 hours.
* **> 2 years:** Same as adult inhaled dosing.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is typically recommended, but caution is advised.
* **Hepatic Impairment:** No specific dose adjustment is typically recommended for overdose treatment, as the goal is to replete glutathione stores. For mucolytic use, caution may be warranted.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Active bronchospasm (for inhaled use).
## Adverse Effects
* **Inhaled:** Bronchospasm, nausea, vomiting, stomatitis, rhinorrhea, urticaria.
* **IV (Overdose):** Anaphylactoid reactions (rash, pruritus, urticaria, angioedema, bronchospasm, dyspnea), nausea, vomiting, flushing, tachycardia.
* **Oral:** Nausea, vomiting, diarrhea, rash.
## Key Drug Interactions
* **Activated Charcoal:** May adsorb oral acetylcysteine, potentially reducing its efficacy in acetaminophen overdose. Separate administration by at least 1 hour.
* **Nitroglycerin:** Potentiation of hypotensive effects. Monitor blood pressure closely.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels (to guide treatment duration).
* Liver function tests (AST, ALT, bilirubin, INR, albumin).
* Renal function and electrolytes.
* Blood glucose.
* **Mucolytic Use:** Respiratory status, sputum production, signs of bronchospasm.
## Clinical Pearls
* For IV acetaminophen overdose, early administration is crucial for optimal efficacy. Treatment should be initiated even if acetaminophen levels are not yet available or are below the nomogram line if there is suspicion of ingestion.
* IV acetylcysteine can cause anaphylactoid reactions. Premedication with an antihistamine may be considered, especially in high-risk patients.
* The 10% IV solution should be diluted with D5W or 0.9% NaCl to a final concentration of no more than 5 mg/mL to reduce the risk of phlebitis and local reactions.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols before administering any medication.*
