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# Acetylcysteine
## Overview
Acetylcysteine is an mucolytic agent and an antidote for acetaminophen overdose. It is available in oral, intravenous, and inhalation formulations.
## Primary Indications
* **Acetaminophen overdose:** To prevent or reduce liver toxicity.
* **Mucolytic:** To thin respiratory secretions in conditions like cystic fibrosis and COPD (inhalation route).
## Adult Dosing
**Acetaminophen Overdose:**
* **Loading Dose:** 150 mg/kg IV infused over 1 hour.
* **Second Dose:** 50 mg/kg IV infused over the next 1 hour.
* **Third Dose:** 100 mg/kg IV infused over the next 16 hours.
* Total duration of infusion is typically 21 hours.
* Maximum dose depends on the calculated total acetaminophen dose and liver function. Consult specific hospital protocols for maximum IV doses and duration.
**Mucolytic (Nebulization):**
* 3-10 mL of 20% solution or 6-10 mL of 10% solution inhaled via nebulizer every 3-4 hours as needed.
## Pediatric Dosing
**Acetaminophen Overdose:**
* Dosing is weight-based and identical to adult dosing:
* Loading Dose: 150 mg/kg IV infused over 1 hour.
* Second Dose: 50 mg/kg IV infused over the next 1 hour.
* Third Dose: 100 mg/kg IV infused over the next 16 hours.
* Maximum dose depends on calculated acetaminophen dose and liver function. Consult specific hospital protocols.
**Mucolytic (Nebulization):**
* 1-2 mL of 20% solution or 2-5 mL of 10% solution inhaled via nebulizer every 3-4 hours as needed.
## Dose Adjustments
No dose adjustments are typically required for hepatic or renal impairment for the acetaminophen overdose protocol.
## Contraindications
* Known hypersensitivity to acetylcysteine.
* Active bronchospasm (for inhalation route).
## Adverse Effects
* **IV:** Anaphylactoid reactions (rash, pruritus, bronchospasm, angioedema, hypotension), nausea, vomiting. Anaphylactoid reactions are more common with rapid infusion.
* **Inhalation:** Bronchorrhea, bronchospasm, stomatitis, nausea.
## Key Drug Interactions
No significant drug interactions are identified with acetylcysteine.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels.
* Liver function tests (AST, ALT, bilirubin, INR).
* Renal function.
* Electrolytes.
* Glucose.
* Clinical status (mental status, vital signs).
* **Mucolytic:**
* Respiratory status, effectiveness of secretion clearance.
* Signs of bronchospasm.
## Clinical Pearls
* For acetaminophen overdose, the antidote is most effective when started within 8-10 hours of ingestion. However, it should be administered regardless of the time elapsed if acetaminophen levels are supratherapeutic or toxicity is suspected.
* Dilute IV acetylcysteine to prevent phlebitis and reduce risk of anaphylactoid reactions. Standard dilutions are often 20 mg/mL.
* Protocols for IV acetylcysteine administration vary; it is essential to follow institutional guidelines.
* Premedication with an antihistamine or bronchodilator may be considered for patients experiencing adverse reactions to nebulized acetylcysteine.
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*Please verify the current prescribing information with the manufacturer's package insert and institutional protocols before making any clinical decisions.*
