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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 toxicity.
* **Mucolytic:** To thin and loosen mucus in respiratory conditions.
## Adult Dosing
### Acetaminophen Overdose
**Oral:**
* **Loading Dose:** 140 mg/kg as a single dose.
* **Subsequent Doses:** 70 mg/kg every 4 hours for 17 doses.
* **Maximum Dose:** Not typically limited by body weight, but consider the total volume for administration.
**Intravenous (IV):**
* **Loading Dose:** 150 mg/kg infused over 60 minutes.
* **Second Infusion:** 50 mg/kg infused over the next 4 hours.
* **Third Infusion:** 100 mg/kg infused over the subsequent 16 hours.
* **Maximum Dose:** Specific maximums depend on the formulation and patient weight, consult product labeling.
### Mucolytic
**Inhaled (nebulized):**
* 1 to 2 mL of a 10% or 20% solution every 3 to 4 hours as needed.
* **Maximum Dose:** Typically 600 mg per day.
## Pediatric Dosing
### Acetaminophen Overdose
Dosing is the same as adults (140 mg/kg oral loading, then 70 mg/kg every 4 hours for 17 doses; or IV protocol).
### Mucolytic
**Inhaled (nebulized):**
* **< 1 year:** 1 mL of a 10% or 20% solution every 2 to 6 hours.
* **≥ 1 year:** 1 to 2 mL of a 10% or 20% solution every 3 to 4 hours as needed.
## Dose Adjustments
No dose adjustments are typically required for renal or hepatic impairment in the setting of acetaminophen overdose when using the standard IV protocol. Dose may need adjustment in mucolytic therapy based on patient tolerance and response.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Active hemorrhage (for oral acetylcysteine).
## Adverse Effects
* **IV:** Anaphylactoid reactions (urticaria, pruritus, rash, bronchospasm, angioedema, dyspnea, hypotension), nausea, vomiting, fever, flushing.
* **Oral:** Nausea, vomiting, diarrhea.
* **Inhaled:** Bronchospasm, stomatitis, nausea, rhinorrhea.
## Key Drug Interactions
* **Activated Charcoal:** May adsorb oral acetylcysteine, reducing its efficacy. Separate administration by at least 1 hour.
* **Nitroglycerin:** May potentiate hypotensive effects.
## Monitoring
* **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests (AST, ALT, bilirubin, INR), glucose, electrolytes, renal function. Monitor for signs of anaphylactoid reaction during IV infusion.
* **Mucolytic:** Respiratory status, bronchospasm, sputum production.
## Clinical Pearls
* The IV route is preferred for severe acetaminophen overdose or when oral intake is not feasible.
* Anaphylactoid reactions are common with IV acetylcysteine but are usually mild and manageable. Premedication is generally not recommended.
* For inhaled acetylcysteine, consider co-administration with a bronchodilator if the patient has reactive airway disease to minimize bronchospasm.
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This information is intended for clinical professionals. Always verify current prescribing information and consult with a pharmacist or physician for patient-specific guidance.
