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# Acetylcysteine
## Overview
Acetylcysteine (N-acetyl-L-cysteine) functions as a mucolytic by splitting disulfide bonds in mucoproteins and as a glutathione precursor/pro-drug in acetaminophen toxicity.
## Primary Indications
* **Acetaminophen Toxicity:** Treatment of potentially hepatotoxic ingestion.
* **Mucolytic Adjunct:** Management of secretions in bronchopulmonary diseases (e.g., COPD, cystic fibrosis).
* **Contrast-Induced Nephropathy (Off-label):** Prophylaxis in high-risk patients.
## Adult Dosing
* **Acetaminophen Toxicity (IV - Acetadote protocol):**
* Loading: 150 mg/kg over 60 minutes.
* Second dose: 50 mg/kg over 4 hours.
* Third dose: 100 mg/kg over 16 hours.
* **Acetaminophen Toxicity (Oral):** 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses.
* **Mucolytic (Inhalation):** 3-5 mL of 20% solution or 6-10 mL of 10% solution via nebulizer 3-4 times daily.
## Pediatric Dosing
* **Acetaminophen Toxicity (IV):** Same mg/kg dosing as adults; follow specific institutional weight-based protocols to avoid fluid overload.
* **Mucolytic (Inhalation):** 3-5 mL of 20% solution or 6-10 mL of 10% solution via nebulizer 3-4 times daily.
## Dose Adjustments
* **Acetaminophen Toxicity:** Adjust total volume and infusion rate in fluid-restricted pediatric patients or those with existing cardiac/renal impairment to prevent hyponatremia or fluid overload.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Oral administration is contraindicated in patients with esophageal varices or significant potential for gastrointestinal hemorrhage.
## Adverse Effects
* **Inhalation:** Bronchospasm (especially in asthma), stomatitis, rhinorrhea, hemoptysis.
* **IV/Oral:** Anaphylactoid reactions (flushing, urticaria, hypotension), nausea, vomiting. Anaphylactoid reactions are dose-dependent and typically occur during the loading dose.
## Key Drug Interactions
* **Inhaled Antibiotics:** Do not mix acetylcysteine with antibiotics (e.g., tetracyclines, aminoglycosides) in the same nebulizer; physical incompatibility may occur.
* **Activated Charcoal:** May decrease absorption of oral acetylcysteine; if charcoal was administered, delay oral acetylcysteine or adjust dosing if charcoal is still in the GI tract.
## Monitoring
* **Acetaminophen Toxicity:** Serum acetaminophen levels (Rumack-Matthew nomogram), ALT/AST, INR/PT, creatinine, and electrolytes. Monitor for signs of anaphylactoid reaction throughout the loading dose.
* **Mucolytic:** Respiratory status, sputum production, and airway patency.
## Clinical Pearls
* **Nebulization:** Always administer a bronchodilator (e.g., albuterol) 10–15 minutes prior to inhaled acetylcysteine to prevent procedure-induced bronchospasm.
* **Smell:** The solution has a characteristic “rotten egg” (sulfur) odor, which may cause patient aversion.
* **Formulation:** Ensure use of the correct formulation (inhalation vs. sterile IV).
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**Disclaimer:** This information is for educational purposes and does not substitute for clinical judgment. Always verify current prescribing information, institutional protocols, and patient-specific contraindications prior to administration.
