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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucoproteins, reducing viscosity. It is also an antidote for acetaminophen overdose.
## Primary Indications
* **Acetaminophen Overdose:** Treatment of acetaminophen toxicity.
* **Mucolytic:** To aid dissolution of thick mucus secretions in respiratory conditions such as bronchitis, emphysema, and cystic fibrosis.
## Adult Dosing
### Acetaminophen Overdose
* **Loading Dose:** 150 mg/kg IV infused over 60 minutes.
* **Second Dose:** 50 mg/kg IV infused over 60 minutes, 4 hours after the loading dose.
* **Subsequent Doses:** 100 mg/kg IV infused over 16 hours (total infusion time of 20 hours, 45 minutes).
* **Maximum Dose:** Limited by the total amount of acetaminophen ingested. For chronic overdose, or when time of ingestion is unknown, it is typically given for a minimum of 21 hours. IV formulation is preferred for initial management. Oral administration may be used for completion of therapy if tolerated.
### Mucolytic
* **Inhalation:** 1-10 mL of a 20% solution or 2-20 mL of a 10% solution every 2-6 hours as needed.
* **Oral:** 200 mg (1 capsule or 5 mL of liquid) two to four times daily.
* **Intravenous (less common for mucolytic):** Dosing is highly variable and depends on the specific indication; consult specific protocols.
## Pediatric Dosing
### Acetaminophen Overdose
* Dosing is the same as adults on a mg/kg basis:
* **Loading Dose:** 150 mg/kg IV infused over 60 minutes.
* **Second Dose:** 50 mg/kg IV infused over 60 minutes, 4 hours after the loading dose.
* **Subsequent Doses:** 100 mg/kg IV infused over 16 hours.
* **Maximum Dose:** Limited by the total amount of acetaminophen ingested.
### Mucolytic
* **Inhalation:**
* **Children < 1 year:** 1-2 mL of 20% solution or 2-4 mL of 10% solution every 3-4 hours.
* **Children > 1 year:** 2-5 mL of 20% solution or 4-10 mL of 10% solution every 3-4 hours.
* **Oral:** 50-100 mg (2.5-5 mL of liquid) two to four times daily.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment. However, caution should be exercised in patients with severe impairment due to potential accumulation.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Consider caution in patients with active bronchospasm.
## Adverse Effects
* **IV:** Anaphylactoid reactions (rash, pruritus, urticaria, bronchospasm, angioedema, dyspnea), tachycardia, hypotension, fever, flushing.
* **Inhalation:** Bronchospasm, stomatitis, rhinorrhea, nausea, vomiting.
* **Oral:** Nausea, vomiting, diarrhea, stomatitis.
## Key Drug Interactions
* **Activated Charcoal:** May adsorb oral acetylcysteine, reducing its efficacy. Separate administration by at least 1 hour if used for acetaminophen overdose.
* **Nitroglycerin:** May potentiate hypotensive effects.
## Monitoring
* **Acetaminophen Overdose:** Monitor serum acetaminophen levels, liver function tests (LFTs), prothrombin time (PT), international normalized ratio (INR), and clinical status (e.g., mental status, bleeding).
* **Mucolytic:** Monitor respiratory status, sputum viscosity, and for signs of bronchospasm.
## Clinical Pearls
* The IV formulation for acetaminophen overdose is associated with a significant risk of anaphylactoid reactions. Slow infusion rates and pretreatment with antihistamines or corticosteroids may be considered.
* For inhalation, acetylcysteine has a noxious odor and may cause bronchospasm. Administer with a bronchodilator if necessary.
* Oral formulations are generally better tolerated for mucolytic therapy than inhaled ones, though efficacy may be less.
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**Disclaimer:** This information is intended for healthcare professionals. It is essential to consult the most current prescribing information and institutional protocols before administering any medication. Dosing may vary based on patient-specific factors and local guidelines.
