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# Acetylcysteine
## Overview
Acetylcysteine (NAC) is a mucolytic agent that also acts as an antidote to acetaminophen overdose by replenishing hepatic glutathione stores. It is available in oral and intravenous formulations.
## Primary Indications
* **Acetaminophen Overdose:** Treatment to prevent or reduce liver damage.
* **Mucolytic:** To thin and loosen mucus in conditions such as chronic bronchitis, emphysema, and cystic fibrosis.
## Adult Dosing
**Acetaminophen Overdose:**
* **Oral:** Loading dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for a total of 17 doses. Maximum dose: 140 mg/kg per dose.
* **Intravenous:** Typically a 3-bag infusion protocol:
* 150 mg/kg over 60 minutes.
* 50 mg/kg over the next 4 hours.
* 100 mg/kg over the subsequent 16 hours.
* Maximum initial dose: 150 mg/kg.
* *Note: Specific IV protocols can vary; consult local institutional guidelines or PDR/Lexicomp for definitive protocol details.*
**Mucolytic:**
* **Oral:** 200 mg twice to three times daily. Higher doses may be used in specific conditions like cystic fibrosis (e.g., 600-1800 mg/day divided doses).
* **Inhaled:** 1-10 mL of a 10-20% solution, or 3-5 mL of a 20% solution, via nebulizer every 2-6 hours.
## Pediatric Dosing
**Acetaminophen Overdose:**
* Dosing is the same as adult dosing based on weight (140 mg/kg loading, 70 mg/kg maintenance for oral; IV protocol generally the same, adjusted for weight).
* *Note: Specific IV protocols can vary; consult local institutional guidelines or PDR/Lexicomp for definitive protocol details.*
**Mucolytic:**
* **Oral:**
* < 1 year: 50 mg twice daily.
* 1-2 years: 50 mg two to three times daily.
* 2-12 years: 100 mg two to three times daily.
* > 12 years: Same as adult dosing.
* **Inhaled:**
* 2-5 years: 1-2 mL of a 10-20% solution via nebulizer every 2-6 hours.
* > 5 years: 3-5 mL of a 20% solution via nebulizer every 2-6 hours.
## Dose Adjustments
* No specific dose adjustments are typically required for hepatic or renal impairment for acetaminophen overdose treatment.
* For mucolytic use, dose may be adjusted based on patient response and tolerability.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Asthma (inhalation use) may require caution due to potential for bronchospasm.
## Adverse Effects
* **Oral:** Nausea, vomiting, diarrhea, stomatitis, rash.
* **Intravenous:** Anaphylactoid reactions (rash, pruritus, urticaria, bronchospasm, angioedema, hypotension), fever, chills. Rapid infusion can increase the risk of anaphylactoid reactions.
* **Inhaled:** Bronchospasm, rhinorrhea, nausea, vomiting, stomatitis.
## Key Drug Interactions
* **Activated Charcoal:** May adsorb oral acetylcysteine, reducing its absorption. If both are used, administer acetylcysteine at least 1 hour after charcoal.
* **Nitroglycerin:** May potentiate the vasodilatory effects of nitroglycerin, leading to hypotension.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels (at appropriate time points to assess risk).
* Liver function tests (AST, ALT, bilirubin, INR) starting at 18-24 hours after ingestion and daily thereafter.
* Renal function.
* Electrolytes.
* **Mucolytic:**
* Pulmonary status (e.g., sputum production, breathing effort).
* Bronchospasm.
## Clinical Pearls
* The effectiveness of acetylcysteine in acetaminophen overdose is time-dependent; treatment should be initiated as soon as possible.
* For IV administration, monitor closely for anaphylactoid reactions, especially during the initial infusion. Consider premedication with an antihistamine if a history of prior reactions exists or if the patient is at high risk.
* The taste and smell of oral acetylcysteine can be unpleasant; it can be mixed with juice or carbonated beverages to improve palatability.
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*Please verify current prescribing information and consult with a healthcare professional before making any clinical decisions.*
