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# Acetylcysteine
## Overview
Acetylcysteine (N-acetylcysteine, NAC) is an mucolytic agent that replenishes intracellular glutathione, a potent antioxidant.
## Primary Indications
* **Acetaminophen Overdose:** Antidote to acetaminophen toxicity.
* **Mucolytic:** Thins and loosens mucus in airway diseases.
## Adult Dosing
### Acetaminophen Overdose
* **Oral:** 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses (total 72 hours).
* **Intravenous (IV):** Protocol-dependent; typically involves a loading dose of 150 mg/kg over 1 hour, followed by 12.5 mg/kg/hour for 4 hours, then 6.25 mg/kg/hour for 16 hours (total 21 hours). Dosing may vary based on local protocols and serum acetaminophen levels.
### Mucolytic
* **Inhalation:** 1-10 mL of 10% or 20% solution every 2-6 hours as needed.
## Pediatric Dosing
### Acetaminophen Overdose
* **Oral:** Same as adult: 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses (total 72 hours).
* **Intravenous (IV):** Follows adult protocols, with careful consideration for fluid status and dosing based on weight. Protocols may vary significantly for neonates and infants.
### Mucolytic
* **Inhalation:** 1-10 mL of 10% or 20% solution every 2-6 hours as needed. Pediatric nebulization protocols may vary.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment in acetaminophen overdose. For mucolytic use, dose adjustments are based on clinical response and tolerance.
## Contraindications
* Hypersensitivity to acetylcysteine.
* Active bronchospasm (for inhalation).
## Adverse Effects
* **Common (Inhalation):** Bronchospasm, nausea, vomiting, stomatitis.
* **Common (IV):** Anaphylactoid reactions (ranging from rash to bronchospasm and hypotension), nausea, vomiting, fever, chills. Rarely, seizures.
* **Common (Oral):** Nausea, vomiting, diarrhea.
## Key Drug Interactions
* **Activated Charcoal:** May adsorb oral acetylcysteine, reducing its absorption. Separate administration by at least 2 hours.
* **Nitroglycerin:** Potential for additive hypotension.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels at appropriate time points.
* Liver function tests (LFTs).
* Coagulation studies.
* Renal function.
* Clinical signs of toxicity.
* For IV administration: Monitor for anaphylactoid reactions.
* **Mucolytic:**
* Respiratory status.
* Sputum production and consistency.
* Signs of bronchospasm.
## Clinical Pearls
* For acetaminophen overdose, treatment should be initiated empirically if acetaminophen ingestion is suspected and the time of ingestion is unknown or if the serum acetaminophen level falls in the potentially toxic range.
* The antidote is most effective when given within 8-10 hours of acetaminophen ingestion, but it remains beneficial even when given later.
* Anaphylactoid reactions to IV acetylcysteine are common and can be managed by slowing the infusion rate and administering antihistamines. Bronchospasm requires prompt attention.
* When used as a mucolytic, ensuring adequate hydration can enhance its effectiveness.
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**Disclaimer:** This information is intended for clinical use and is not exhaustive. Always consult the current prescribing information and relevant clinical guidelines before making therapeutic decisions. Dosing and protocols can vary.
