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# Acetylcysteine
## Overview
N-acetylcysteine (NAC) is an inhaled mucolytic agent that breaks disulfide bonds in mucus, decreasing its viscosity. It is also available intravenously for acetaminophen overdose and investigational uses.
## Primary Indications
* **Inhaled:** Adjunct treatment of abnormal mucus secretions in patients with bronchitis, emphysema, chronic tracheobronchitis, bronchiectasis, cystic fibrosis, and atelectasis.
* **Intravenous:** Treatment of acetaminophen overdose.
## Adult Dosing
* **Inhaled:** 3 to 5 mL of 10% or 20% solution via nebulizer every 4 to 12 hours. Maximum dose is 3000 mg (30 mL of 10% solution or 15 mL of 20% solution) per administration.
* **Intravenous (Acetaminophen Overdose):** Oral loading dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses. IV dosing protocols vary significantly by institution and may involve higher initial doses and longer durations. **Consult specific institutional protocols or national guidelines for IV NAC dosing in acetaminophen overdose.**
## Pediatric Dosing
* **Inhaled:** 1 to 2 mL of 10% or 20% solution via nebulizer every 4 to 12 hours.
* **Intravenous (Acetaminophen Overdose):** Dosing is the same as adults (140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses). **Consult specific institutional protocols or national guidelines for IV NAC dosing in acetaminophen overdose.**
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment for inhaled NAC. IV NAC dosing for acetaminophen overdose is weight-based and does not typically require adjustment for hepatic or renal impairment, though prolonged treatment may warrant consideration.
## Contraindications
* **Inhaled:** Hypersensitivity to acetylcysteine.
* **Intravenous:** Hypersensitivity to acetylcysteine.
## Adverse Effects
* **Inhaled:** Bronchospasm (especially in asthmatics), nausea, vomiting, stomatitis, rhinorrhea, drowsiness, chest tightness.
* **Intravenous:** Anaphylactoid reactions (rash, pruritus, bronchospasm, angioedema, hypotension), nausea, vomiting.
## Key Drug Interactions
* **Inhaled:** Potentially inactivates some antibiotics (e.g., ampicillin, ampicillin/sulbactam, erythromycin, tetracyclines) if mixed directly. Administer antibiotics separately. May react with nitrofurantoin and certain other agents.
* **Intravenous:** No significant drug interactions identified.
## Monitoring
* **Inhaled:** Monitor for bronchospasm, respiratory status, and effectiveness of mucolysis.
* **Intravenous (Acetaminophen Overdose):** Monitor acetaminophen levels, liver function tests, and signs of anaphylactoid reaction.
## Clinical Pearls
* **Inhaled:** Bronchodilator pre-treatment may be beneficial if bronchospasm is a concern. If the patient has copious secretions, consider suctioning before nebulization.
* **Intravenous:** Early administration of IV NAC is critical for optimal outcomes in acetaminophen overdose. The smell can be unpleasant; however, its importance in preventing liver toxicity outweighs this side effect.
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**Disclaimer:** This information is for educational purposes only and does not constitute medical advice. Always verify current prescribing information with official drug product labeling, institutional protocols, and relevant clinical guidelines before making any treatment decisions.
