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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that reduces the viscosity of respiratory secretions. It also acts as an antidote for acetaminophen overdose by replenishing hepatic glutathione stores.
## Primary Indications
* **Acetaminophen Overdose:** Primary indication for N-acetylcysteine (NAC) therapy.
* **Mucolytic:** Adjunctive therapy for conditions with thick mucus secretions (e.g., chronic bronchitis, cystic fibrosis, pneumonia). Off-label use for this indication is common.
## Adult Dosing
**Acetaminophen Overdose:**
* **Oral:** Initial dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses (total of 72 hours). Maximum initial dose is 140 mg/kg (not to exceed 14000 mg).
* **Intravenous:** Recommended protocols vary. Common regimens include a 3-bag infusion:
* Bag 1: 150 mg/kg over 60 minutes (max 15000 mg).
* Bag 2: 50 mg/kg over the next 4 hours (max 5000 mg).
* Bag 3: 100 mg/kg over the next 16 hours (max 10000 mg).
* *Note:* Specific IV protocols may vary based on local institutional guidelines and availability of specific formulations.
**Mucolytic:**
* **Inhaled:** 10% solution: 3-5 mL nebulized every 3-4 hours. 20% solution: 3-5 mL nebulized every 3-4 hours. Maximum daily dose is generally not specified but should be guided by clinical response.
## Pediatric Dosing
**Acetaminophen Overdose:**
* **Oral:** Same as adult: 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses.
* **Intravenous:** Same as adult IV protocols, adjusted for weight.
**Mucolytic:**
* **Inhaled:**
* Age < 1 year: 1-2 mL of 10% solution nebulized every 2-6 hours.
* Age > 1 year: 3-5 mL of 10% solution nebulized every 3-4 hours. (20% solution may be used similarly, but may cause more bronchospasm).
## Dose Adjustments
No specific dose adjustments are routinely recommended for hepatic or renal impairment, but caution should be exercised.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Active gastrointestinal bleed (for oral formulations).
## Adverse Effects
* **Most Common (Inhaled):** Bronchospasm, nausea, vomiting, stomatitis.
* **Most Common (IV for acetaminophen overdose):** Anaphylactoid reactions (urticaria, pruritus, rash, angioedema, bronchospasm, dyspnea, hypotension), nausea, vomiting.
* **Oral:** Nausea, vomiting, diarrhea.
## Key Drug Interactions
* **Activated Charcoal:** May adsorb oral acetylcysteine, reducing its absorption. Separate administration by at least 1 hour.
* **Nitroglycerin:** Potential for additive hypotensive effects. Monitor blood pressure closely.
## Monitoring
* **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests (LFTs), prothrombin time (PT)/international normalized ratio (INR), blood glucose, renal function.
* **Mucolytic:** Respiratory status, signs of bronchospasm, sputum production.
## Clinical Pearls
* For inhaled acetylcysteine, concurrent administration of a bronchodilator may be necessary to mitigate bronchospasm.
* Nausea and vomiting are common with oral administration; consider antiemetics.
* Anaphylactoid reactions with IV acetylcysteine are usually not contraindications to continued therapy, but require careful management.
* Always consult the most current prescribing information for detailed dosing and administration guidelines, especially for intravenous protocols in acetaminophen overdose.
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**Disclaimer:** This information is intended for clinical professionals and does not replace individual clinical judgment or the official prescribing information. Always verify current drug information with the product's official labeling and consider patient-specific factors.
