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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that decreases the viscosity of respiratory tract secretions. It also acts as an antidote for acetaminophen overdose by replenishing hepatic glutathione stores.
## Primary Indications
* **Acetaminophen Overdose:** Treatment of acetaminophen overdose.
* **Mucolytic:** Adjunct therapy for conditions with excessive or thickened mucus, such as chronic bronchitis, emphysema, cystic fibrosis, and pneumonia.
## Adult Dosing
### Acetaminophen Overdose
* **IV:** Administer a loading dose of 150 mg/kg over 1 hour, followed by 50 mg/kg over 4 hours, then 100 mg/kg over the next 16 hours. A maximum total dose of 300 mg/kg is typically recommended over 21 hours, though some protocols may extend or adjust based on acetaminophen levels and clinical status.
* **PO:** Administered as a 20% solution (200 mg/mL). Loading dose: 140 mg/kg. Maintenance dose: 70 mg/kg every 4 hours for 17 doses. The 20% solution may be diluted to a 5% solution with a carbonated beverage or juice to improve palatability.
### Mucolytic
* **Inhaled:** 1-10 mL of a 10% or 20% solution administered via nebulizer every 2-6 hours. Alternatively, 3-5 mL of a 20% solution or 6-10 mL of a 10% solution can be given every 3-4 hours. Dosing can be adjusted based on patient response and protocol.
## Pediatric Dosing
### Acetaminophen Overdose
* Dosing is the same as adult IV and PO dosing (150 mg/kg over 1 hour, then 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours for IV; 140 mg/kg loading, then 70 mg/kg every 4 hours for 17 doses for PO).
### Mucolytic
* **Inhaled:** For infants and children, 1-2 mL of a 20% solution or 2-4 mL of a 10% solution every 2-6 hours. Dosing should be individualized.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment when used for acetaminophen overdose due to its pharmacokinetic profile. For mucolytic use, adjustments are based on patient response and tolerance.
## Contraindications
* Hypersensitivity to acetylcysteine.
* Use with caution in patients with asthma or reactive airway disease due to potential for bronchospasm.
## Adverse Effects
### Acetaminophen Overdose (IV)
* Anaphylactoid reactions (rash, pruritus, urticaria, angioedema, bronchospasm, dyspnea) are the most common and can be severe. Nausea and vomiting may also occur.
### Acetaminophen Overdose (PO)
* Nausea, vomiting, and diarrhea are common. Less frequent include rash and fever.
### Mucolytic (Inhaled)
* Bronchospasm (especially in asthmatics), rhinorrhea, nausea, vomiting, stomatitis.
## Key Drug Interactions
No significant drug interactions are commonly reported for IV or inhaled acetylcysteine.
## Monitoring
* **Acetaminophen Overdose:** Monitor acetaminophen and its metabolites, hepatic transaminases (ALT, AST), INR, bilirubin, glucose, electrolytes, and renal function. Clinical signs of anaphylactoid reactions.
* **Mucolytic:** Monitor respiratory status, sputum volume and viscosity, and for signs of bronchospasm.
## Clinical Pearls
* For IV administration in acetaminophen overdose, rapid infusion can increase the risk of anaphylactoid reactions. Administer slowly as directed.
* Oral acetylcysteine has an unpleasant sulfurous odor and taste, which can lead to poor compliance. Dilution can improve palatability.
* If bronchospasm occurs with inhaled acetylcysteine, it can be managed with bronchodilator therapy. Discontinuation may be necessary.
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*Disclaimer: This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult current prescribing information and relevant clinical guidelines for the most up-to-date and comprehensive drug information.*
