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# Acetylcysteine
## Overview
Acetylcysteine (NAC) is a mucolytic agent that decreases the viscosity of respiratory tract secretions. It also acts as an antidote for acetaminophen overdose.
## Primary Indications
* **Acetaminophen Overdose:** Treatment of acetaminophen toxicity.
* **Mucolytic:** Adjunctive therapy for conditions with excessive or thickened bronchial secretions (e.g., chronic bronchitis, emphysema, cystic fibrosis, atelectasis).
## Adult Dosing
**Acetaminophen Overdose:**
* **Oral:** Initial dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 additional doses (total of 18 doses). Maximum dose: 140 mg/kg per dose.
* **Intravenous:** Typically initiated with a loading dose of 150 mg/kg over 60 minutes, followed by 50 mg/kg over 10 hours, and then 100 mg/kg over 16 hours. Protocols may vary.
**Mucolytic:**
* **Nebulization:** 3-5 mL of 20% solution or 6-10 mL of 10% solution every 2-6 hours.
* **Direct Instillation (tracheostomy):** 1-2 mL of 10-20% solution every 1-4 hours.
## Pediatric Dosing
**Acetaminophen Overdose:**
* **Oral:** 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 additional doses.
* **Intravenous:** Protocols vary but generally follow adult weight-based dosing with adjustments for prolonged infusion times. Consult specific institutional guidelines.
**Mucolytic:**
* **Nebulization:** Similar to adults, typically 3-5 mL of 20% or 6-10 mL of 10% solution every 2-6 hours.
## Dose Adjustments
No specific dose adjustments are generally required for renal or hepatic impairment.
## Contraindications
Hypersensitivity to acetylcysteine or any component of the formulation.
## Adverse Effects
* **Nebulization:** Bronchospasm (especially in asthmatics), stomatitis, nausea, vomiting, rhinorrhea.
* **Intravenous:** Anaphylactoid reactions (rash, urticaria, angioedema, bronchospasm, hypotension), fever, chills.
* **Oral:** Nausea, vomiting, diarrhea.
## Key Drug Interactions
* **Activated Charcoal:** Can adsorb oral acetylcysteine, reducing its efficacy in acetaminophen overdose. Administer charcoal at least 1 hour *after* oral acetylcysteine or hold acetylcysteine until charcoal is cleared.
## Monitoring
* **Acetaminophen Overdose:** Monitor acetaminophen levels, liver function tests (LFTs), prothrombin time (PT), international normalized ratio (INR), and clinical signs of hepatotoxicity.
* **Mucolytic:** Monitor respiratory status, effectiveness in clearing secretions, and for adverse effects such as bronchospasm.
## Clinical Pearls
* The smell of acetylcysteine can be unpleasant; however, this does not typically indicate loss of efficacy.
* For nebulized acetylcysteine, co-administration with a bronchodilator may be necessary to mitigate bronchospasm.
* Intravenous acetylcysteine can cause anaphylactoid reactions. Closely monitor patients for these effects and be prepared to manage them.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols before administering any medication.*
