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# Acetylcysteine
## Overview
Acetylcysteine (N-acetylcysteine, NAC) is an mucolytic agent and an antidote for acetaminophen overdose.
## Primary Indications
* **Acetaminophen Overdose:** Treatment of acetaminophen poisoning.
* **Mucolytic Agent:** To thin and loosen mucus secretions in the airways (e.g., in cystic fibrosis, COPD).
## Adult Dosing
* **Acetaminophen Overdose:**
* **Oral:** Initial dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses. Maximum single oral dose is 1000 mg.
* **Intravenous (IV):** Protocol varies by institution; commonly involves an initial loading dose followed by maintenance infusions over 20-72 hours. A common regimen is a 150 mg/kg loading dose over 1 hour, followed by 12.5 mg/kg/hour for 4 hours, then 6.25 mg/kg/hour for up to 72 hours. The total daily dose should not exceed 300 mg/kg.
* **Mucolytic Agent:**
* **Nebulized:** 3-5 mL of 20% solution or 6-10 mL of 10% solution every 2-6 hours as needed.
* **Oral:** 200 mg twice daily to 600 mg three times daily.
## Pediatric Dosing
* **Acetaminophen Overdose:**
* **Oral:** 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses.
* **Intravenous (IV):** Dosing adjusted based on weight and protocol, similar to adults but with weight-based calculations.
* **Mucolytic Agent:**
* **Nebulized:** 1-2 mL of 20% solution or 2-4 mL of 10% solution every 2-6 hours as needed.
* **Oral:** 10 mg/kg per dose every 4-6 hours, maximum dose 200 mg per dose or 600 mg/day.
## Dose Adjustments
No specific dose adjustments are generally recommended for hepatic or renal impairment for acetaminophen overdose treatment.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
## Adverse Effects
* **Nebulized:** Bronchospasm, bronchoconstriction, stomatitis, nausea, vomiting, rhinorrhea.
* **Intravenous:** Anaphylactoid reactions (rash, pruritus, urticaria, angioedema, bronchospasm, dyspnea, hypotension), nausea, vomiting.
* **Oral:** Nausea, vomiting, diarrhea, rash.
## Key Drug Interactions
* Activated charcoal may bind to oral acetylcysteine, reducing absorption. Administer acetylcysteine at least 1 hour after activated charcoal.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels.
* Liver function tests (LFTs).
* Prothrombin time (PT).
* Renal function.
* Electrolytes.
* **Mucolytic Agent:**
* Pulmonary status (e.g., auscultation, oxygen saturation).
* Patient's subjective response.
## Clinical Pearls
* For IV administration in acetaminophen overdose, monitor for anaphylactoid reactions, especially during the initial loading dose. Premedication with an antihistamine may be considered.
* If bronchospasm occurs with nebulized acetylcysteine, a bronchodilator should be administered.
* The smell of acetylcysteine can be unpleasant.
* If the patient vomits within 1 hour of receiving oral acetylcysteine, the dose should be re-administered.
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*This information is intended for healthcare professionals. Always consult the current prescribing information and institutional protocols for complete details and to verify dosage and safety before use.*
