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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent and an antidote for acetaminophen overdose. It works by breaking disulfide bonds in mucoproteins, reducing mucus viscosity. As an antidote, it replenishes glutathione stores in the liver.
## Primary Indications
* Acetaminophen overdose
* Adjunct treatment for conditions with thick mucus secretions (e.g., cystic fibrosis, chronic bronchitis, pneumonia, tracheostomy care)
## Adult Dosing
### Acetaminophen Overdose
The standard intravenous (IV) protocol involves a loading dose followed by maintenance doses over 72 hours. A common protocol is:
* **Loading dose:** 150 mg/kg IV infused over 1 hour.
* **Second dose:** 50 mg/kg IV infused over 4 hours.
* **Third dose:** 100 mg/kg IV infused over 16 hours.
The total dose can be up to 300 mg/kg over 21 hours. Oral administration is also used, with a typical protocol involving 140 mg/kg orally as a loading dose, followed by 70 mg/kg orally every 4 hours for 17 doses.
### Mucolytic Therapy
* **Inhaled:** 3 mL of 20% solution or 6 mL of 10% solution nebulized every 4-12 hours.
* **Intravenous (for other indications, not standard):** Typically 200 mg/kg/day IV divided every 4-6 hours, though this is less common and requires careful monitoring.
## Pediatric Dosing
### Acetaminophen Overdose
Dosing is the same as adults on a weight-based calculation (150 mg/kg IV loading, then 50 mg/kg IV, then 100 mg/kg IV). Oral dosing is also weight-based (140 mg/kg PO loading, then 70 mg/kg PO).
### Mucolytic Therapy
* **Inhaled:** 10% solution: 1-2 mL nebulized every 4-12 hours. 20% solution: 1 mL nebulized every 4-12 hours.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, though caution and closer monitoring may be warranted in severe cases.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Active hemorrhage, especially gastrointestinal bleeding (for oral use, though IV use in overdose can proceed with caution).
## Adverse Effects
* **Anaphylactoid reactions:** Bronchospasm, rash, urticaria, pruritus, angioedema, nausea, vomiting, diarrhea. These are more common with IV administration.
* **Other:** Stomatitis, rhinorrhea, drowsiness, fever, chills.
## Key Drug Interactions
* **Activated charcoal:** May adsorb acetylcysteine, reducing its absorption when given orally for overdose. Separate administration by at least 1 hour.
* **Nitroglycerin:** Potential for additive hypotension and headache.
## Monitoring
* **Acetaminophen Overdose:** Acetaminophen and salicylate levels, liver function tests (LFTs), coagulation studies, renal function, glucose levels, and clinical status. Monitor for signs of anaphylactoid reaction.
* **Mucolytic Therapy:** Respiratory status, pulmonary secretions, signs of bronchospasm.
## Clinical Pearls
* For IV acetaminophen overdose, early administration is crucial for efficacy.
* Anaphylactoid reactions are common with IV acetylcysteine; premedication with an antihistamine or corticosteroid may be considered, particularly for mucolytic therapy.
* Oral acetylcysteine can be unpleasant due to its sulfurous odor and taste; masking with juice or soda is often necessary. Vomiting can occur, and repeat dosing may be required if vomiting occurs within 1 hour of administration.
* Inhaled acetylcysteine can cause bronchospasm, especially in asthmatics.
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*This information is intended for clinical use and does not substitute for the latest prescribing information. Always consult the official drug monograph or product insert for the most current and complete details.*
