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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent and an antidote for acetaminophen overdose. It is available in oral and intravenous formulations.
## Primary Indications
* **Acetaminophen overdose:** To prevent or reduce the severity of liver damage.
* **Mucolytic:** To thin and loosen mucus in patients with conditions such as cystic fibrosis, chronic obstructive pulmonary disease (COPD), and pneumonia.
## Adult Dosing
* **Acetaminophen overdose:**
* **Loading dose:** 150 mg/kg intravenously over 1 hour.
* **Maintenance dose:** 12.5 mg/kg/hour intravenously for 20 hours.
* Alternative oral protocol: 140 mg/kg orally as a loading dose, followed by 70 mg/kg orally every 4 hours for 17 doses.
* Dosing may be adjusted based on acetaminophen levels and liver function. Protocols can vary; confirm local guidelines.
* **Mucolytic:**
* **Oral:** 200 mg to 400 mg twice to three times daily.
* **Nebulized:** 1 to 10 mL of a 10% or 20% solution every 2 to 6 hours as needed. Some protocols recommend 3 to 5 mL of 20% solution or 6 to 10 mL of 10% solution.
## Pediatric Dosing
* **Acetaminophen overdose:** Dosing is weight-based and similar to adults, often calculated per kilogram of body weight. Confirm specific pediatric protocols.
* **Mucolytic:**
* **Oral:** Typically 50 mg/kg to 100 mg/kg per dose every 4 to 12 hours, not to exceed adult doses.
* **Nebulized:** 1 mL to 3 mL of a 10% or 20% solution every 2 to 6 hours as needed.
## Dose Adjustments
No dose adjustments are typically required for renal or hepatic impairment for the antidote indication. For mucolytic use, adjustments are not usually necessary unless adverse effects occur.
## Contraindications
* Hypersensitivity to acetylcysteine.
* Active gastrointestinal bleeding (for oral formulation, caution advised).
## Adverse Effects
* **Intravenous:** Anaphylactoid reactions (rash, urticaria, bronchospasm, angioedema, dyspnea, hypotension), nausea, vomiting, fever, headache.
* **Oral:** Nausea, vomiting, diarrhea, stomatitis, rash.
* **Nebulized:** Bronchospasm (especially in asthmatics), rhinorrhea, nausea, vomiting, stomatitis.
## Key Drug Interactions
* **Activated charcoal:** Can adsorb oral acetylcysteine, reducing its absorption. Administer oral acetylcysteine at least 1 hour after activated charcoal.
* **Nitroglycerin:** Potential for additive hypotension.
## Monitoring
* **Acetaminophen overdose:** Plasma acetaminophen levels, liver function tests (AST, ALT, bilirubin, INR), blood glucose, electrolytes, and renal function. Monitor for signs of anaphylaxis.
* **Mucolytic:** Respiratory status, sputum production, and for adverse effects like bronchospasm.
## Clinical Pearls
* For acetaminophen overdose, prompt initiation of acetylcysteine is crucial for efficacy.
* Oral acetylcysteine has an unpleasant odor and taste; dilution and flavorings may improve palatability.
* Be prepared to manage anaphylactoid reactions with intravenous acetylcysteine.
* Nebulized acetylcysteine can sometimes worsen bronchospasm; co-administration with a bronchodilator may be considered.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant guidelines for definitive patient care decisions. Drug information can change.*
