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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that reduces the viscosity of respiratory secretions. It is also an antidote for acetaminophen overdose.
## Primary Indications
* **Acetaminophen Overdose:** To prevent or reduce liver damage following an overdose of acetaminophen.
* **Mucolytic Agent:** To thin and loosen mucus in patients with chronic bronchopulmonary diseases (e.g., COPD, cystic fibrosis) and as an adjunct to bronchodilator therapy in patients with asthma or bronchitis.
## Adult Dosing
### Acetaminophen Overdose (Oral)
* **Loading Dose:** 140 mg/kg orally, followed by 70 mg/kg orally every 4 hours for 17 doses.
* **Intravenous (IV) Dosing:** Protocols vary; typically involves a loading dose of 150 mg/kg infused over 1 hour, followed by 12.5 mg/kg/hour for 4 hours, then 6.25 mg/kg/hour for 16 hours. Consult specific institutional protocols.
### Acetaminophen Overdose (Intravenous)
* Protocols vary; consult specific institutional guidelines. A common regimen involves:
* Loading dose: 150 mg/kg IV over 1 hour.
* Second infusion: 12.5 mg/kg/hour IV over 4 hours.
* Third infusion: 6.25 mg/kg/hour IV over 16 hours.
### Mucolytic Agent (Oral/Nebulized)
* **Oral:** 200 mg to 400 mg twice or three times daily.
* **Nebulized:** 1 to 2 mL of a 20% solution or 3 to 5 mL of a 10% solution every 2 to 6 hours as needed.
## Pediatric Dosing
### Acetaminophen Overdose (Oral)
* **Loading Dose:** 140 mg/kg orally, followed by 70 mg/kg orally every 4 hours for 17 doses.
### Acetaminophen Overdose (Intravenous)
* Protocols vary; consult specific institutional guidelines. Dosing is based on weight similar to adults but adjusted for pediatric weight ranges.
### Mucolytic Agent (Nebulized)
* **Nebulized:** 1 mL of a 20% solution or 2 to 3 mL of a 10% solution every 2 to 6 hours as needed.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment for the mucolytic indication. For acetaminophen overdose, dose adjustments are based on serum acetaminophen levels and time since ingestion.
## Contraindications
* Hypersensitivity to acetylcysteine.
## Adverse Effects
* **Common (Nebulized):** Bronchospasm, rhinorrhea, nausea, vomiting, stomatitis.
* **Common (Oral):** Nausea, vomiting, diarrhea.
* **Serious (IV for overdose):** Anaphylactoid reactions (ranging from rash, pruritus to bronchospasm, angioedema, and rarely, anaphylactic shock), hypotension, tachycardia.
## Key Drug Interactions
* **Activated Charcoal:** Can adsorb acetylcysteine when given orally, reducing its absorption. Separate administration by at least 1 hour.
* **Nitroglycerin:** May potentiate the vasodilatory effects of nitroglycerin, leading to hypotension.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels (at specific time points based on Rumack-Matthew nomogram).
* Liver function tests (AST, ALT, bilirubin, INR).
* Renal function tests.
* Electrolytes.
* Prothrombin time.
* **Mucolytic Agent:**
* Respiratory status, sputum volume, and consistency.
* Bronchospasm.
## Clinical Pearls
* For acetaminophen overdose, early initiation of acetylcysteine is crucial for efficacy.
* IV acetylcysteine for acetaminophen overdose has a higher risk of anaphylactoid reactions, requiring careful monitoring.
* Nebulized acetylcysteine can induce bronchospasm; co-administration with a bronchodilator may be beneficial.
* The odor of acetylcysteine (sulfur) is characteristic and can be unpleasant.
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*This information is intended for clinical use and does not substitute for a comprehensive review of current prescribing information and institutional protocols. Always verify the most up-to-date drug information before administration.*
