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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that works by breaking disulfide bonds in mucus, reducing its viscosity. It is also an antidote for acetaminophen overdose.
## Primary Indications
* Acetaminophen overdose
* Pulmonary conditions with thick mucus secretions (e.g., cystic fibrosis, chronic bronchitis, pneumonia)
## Adult Dosing
**Acetaminophen Overdose:**
* **Intravenous (IV):** Typically a 3-bag or 4-bag regimen over 20 hours.
* Loading dose: 150 mg/kg IV infused over 60 minutes.
* Second infusion: 50 mg/kg IV infused over 60 minutes.
* Third infusion: 100 mg/kg IV infused over 16 hours.
* Maximum dose: Not to exceed 150 mg/kg in the first 8 hours.
* **Oral (PO):** Usually a 72-hour regimen.
* Loading dose: 140 mg/kg PO.
* Subsequent doses: 70 mg/kg PO every 4 hours for 17 doses.
* Maximum dose: 140 mg/kg loading dose, followed by 70 mg/kg for 17 doses.
**Mucolytic Agent:**
* **Nebulization:** 10% solution: 3-5 mL every 3-4 hours; 20% solution: 3-5 mL every 3-4 hours. Dosing may be adjusted based on patient response and mucus production.
* **Intratracheal:** 1-2 mL of 10% or 20% solution every 1-4 hours.
* **Oral:** 200 mg (using effervescent tablets or granules) twice daily or 600 mg once daily. This route is less common and primarily for chronic conditions.
## Pediatric Dosing
**Acetaminophen Overdose (IV):**
* Same as adult dosing (150 mg/kg loading, 50 mg/kg over 60 minutes, then 100 mg/kg over 16 hours).
* Consider diluting in 5% dextrose in water (D5W) to avoid fluid overload in infants.
**Acetaminophen Overdose (PO):**
* Same as adult dosing (140 mg/kg loading, 70 mg/kg every 4 hours for 17 doses).
**Mucolytic Agent (Nebulization):**
* **<1 year:** 1-2 mL of 10% solution every 2-6 hours.
* **1-2 years:** 2-3 mL of 10% solution every 3-4 hours.
* **>2 years:** 3-5 mL of 10% solution every 3-4 hours.
* Dosing can also be based on weight: 10-20 mg/kg/dose every 4-12 hours. Consult local protocol.
## Dose Adjustments
* **Renal impairment:** No specific dose adjustment is typically required, but caution may be warranted.
* **Hepatic impairment:** No specific dose adjustment is typically required for overdose treatment, but prolonged monitoring may be necessary.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
## Adverse Effects
* **Common (especially with nebulization):** Bronchospasm, rhinorrhea, nausea, vomiting, stomatitis.
* **IV administration:** Anaphylactoid reactions (rash, urticaria, angioedema, bronchospasm, dyspnea), nausea, vomiting, flushing, tachycardia, hypotension.
* **Oral administration:** Nausea, vomiting, diarrhea.
## Key Drug Interactions
* **Activated charcoal:** May adsorb oral acetylcysteine, reducing its absorption. Separate administration by at least 1 hour.
* **Nitroglycerin:** May potentiate hypotensive effects.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels (obtain 4 hours post-ingestion and at or after 12 hours post-ingestion for nomogram assessment).
* Liver function tests (LFTs), prothrombin time (PT), international normalized ratio (INR), creatinine, electrolytes, blood glucose.
* Monitor for signs of hepatotoxicity.
* **Mucolytic Use:**
* Respiratory status, sputum volume and viscosity, airway clearance.
* For nebulized administration, monitor for bronchospasm.
## Clinical Pearls
* For IV acetaminophen overdose, prompt initiation of treatment is crucial, especially if the estimated ingestion is greater than the toxic dose or if serum levels are in the treatment range of the nomogram.
* Oral acetylcysteine has an unpleasant sulfurous odor and taste, which can lead to poor compliance. It can be masked with juice or carbonated beverages.
* Nebulized acetylcysteine can induce bronchospasm, especially in patients with asthma or hyperreactive airways. Co-administration of a bronchodilator may be necessary.
* Anaphylactoid reactions with IV acetylcysteine are common but usually manageable with symptomatic treatment and do not preclude completion of therapy.
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*This information is intended for healthcare professionals and should not be used as a substitute for professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions.*
