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# Acetylcysteine
## Overview
Acetylcysteine (NAC) is an inhaled mucolytic agent that breaks disulfide bonds in mucus, reducing viscosity. It is also used orally and intravenously as an antidote for acetaminophen overdose.
## Primary Indications
* **Inhaled:** To thin mucus secretions in patients with cystic fibrosis, chronic bronchitis, emphysema, and other pulmonary diseases.
* **Intravenous/Oral:** As an antidote for acetaminophen overdose.
## Adult Dosing
* **Inhaled:** 1 to 10 mL of a 10% or 20% solution every 2-6 hours as needed. Dosing frequency and concentration may be adjusted based on patient response and tolerance.
* **Acetaminophen Overdose (Oral/IV):**
* **Oral:** Loading dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses.
* **Intravenous:** Dosing protocols vary but often involve an initial loading dose followed by maintenance infusions over 20-24 hours. A common regimen is 150 mg/kg IV over 1 hour, then 12.5 mg/kg/hour IV for 4 hours, then 6.25 mg/kg/hour IV for 16 hours. **Consult local protocol for specific IV regimens.**
## Pediatric Dosing
* **Inhaled:**
* **Cystic Fibrosis:** 1 to 10 mL of a 10% or 20% solution every 2-6 hours as needed.
* **Less than 1 year:** 1 mL of a 10% solution every 2-6 hours.
* **Acetaminophen Overdose (Oral/IV):** Dosing is weight-based and similar to adults, adjusted for pediatric weight. **Consult local protocol for specific IV regimens.**
## Dose Adjustments
* No specific dose adjustments are typically required for hepatic or renal impairment for inhaled use.
* For acetaminophen overdose, doses are calculated based on weight.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* **Inhaled:** Use with caution in patients with severe asthma due to potential for bronchospasm.
## Adverse Effects
* **Inhaled:** Bronchospasm, nausea, vomiting, stomatitis, rhinorrhea, urticaria, drowsiness.
* **Intravenous:** Anaphylactoid reactions (urticaria, angioedema, flushing, rash, pruritus, bronchospasm, dyspnea, hypotension), fever, nausea, vomiting.
## Key Drug Interactions
* **Inhaled:** May inactivate some antibiotics if administered concurrently in the same nebulizer (e.g., ampicillin, ampicillin/sulbactam, erythromycin, tetracyclines). Separate administration if possible.
* **Intravenous:** No significant interactions known with acetaminophen.
## Monitoring
* **Inhaled:** Monitor respiratory status, lung sounds, and for signs of bronchospasm.
* **Acetaminophen Overdose:** Monitor acetaminophen levels, liver function tests (LFTs), prothrombin time (PT), international normalized ratio (INR), and clinical signs of liver toxicity.
## Clinical Pearls
* When administering inhaled acetylcysteine, pre-treatment with a bronchodilator may be necessary for patients with asthma or reactive airway disease.
* The odor of acetylcysteine can be unpleasant; however, this does not affect its efficacy.
* For acetaminophen overdose, early initiation of NAC is crucial for optimal efficacy.
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***Disclaimer:** This information is intended for clinical use and is not a substitute for professional medical advice. Always consult the most current prescribing information and local protocols for definitive guidance.*
