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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 the antidote for acetaminophen overdose.
## Primary Indications
* Acetaminophen overdose
* Adjunct therapy in chronic bronchitis and other respiratory conditions with excessive mucus production
## Adult Dosing
**Acetaminophen Overdose:**
* **Loading Dose:** 150 mg/kg intravenously (IV) infused over 1 hour.
* **Second Dose:** 50 mg/kg IV infused over 4 hours.
* **Third Dose:** 100 mg/kg IV infused over 16 hours.
* *Note: Total daily dose should not exceed 300 mg/kg. Dosing may be adjusted based on acetaminophen levels and clinical response. Local protocols may vary.*
**Mucolytic Therapy:**
* **Oral:** 200 mg to 400 mg by mouth twice daily.
* **Intravenous:** 600 mg by mouth three to four times daily.
* **Nebulized:** 3 mL to 5 mL of 10% or 20% solution every 4 to 6 hours, or 1 mL to 2 mL of 10% solution every 30 minutes to 1 hour via nebulizer.
## Pediatric Dosing
**Acetaminophen Overdose:**
* Same protocol as adults (150 mg/kg IV over 1 hour, then 50 mg/kg IV over 4 hours, then 100 mg/kg IV over 16 hours).
* *Note: If patient weighs less than 40 kg, adjust the total volume of IV fluids to prevent fluid overload.*
**Mucolytic Therapy:**
* **Nebulized:** 1 mL to 2 mL of 10% solution every 30 minutes to 1 hour via nebulizer. Alternative: 20% solution diluted to 10% with sterile water or saline.
## Dose Adjustments
No specific dose adjustments are typically required for hepatic or renal impairment for the antidote indication. For mucolytic indications, dose adjustments are generally based on clinical response and tolerability.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Active gastrointestinal bleeding (for oral formulation).
## Adverse Effects
* **Anaphylactoid Reactions:** Rash, pruritus, urticaria, bronchospasm, angioedema, dyspnea, and hypotension (more common with IV administration).
* **Gastrointestinal:** Nausea, vomiting, diarrhea, stomatitis.
* **Other:** Fever, headache, rhinorrhea.
## Key Drug Interactions
* **Activated Charcoal:** Can reduce the absorption of oral acetylcysteine. Administer oral acetylcysteine at least 1 hour after activated charcoal.
* **Nitroglycerin:** May potentiate the vasodilatory effects of nitroglycerin.
## Monitoring
* **Acetaminophen Overdose:** Serial acetaminophen and liver function tests. Monitor for signs of anaphylactoid reactions.
* **Mucolytic Therapy:** Monitor respiratory status, sputum viscosity, and effectiveness of airway clearance. Monitor for adverse effects.
## Clinical Pearls
* For IV administration in acetaminophen overdose, hypotension and anaphylactoid reactions are the most serious adverse events. Slowing the infusion rate may help manage these.
* Oral acetylcysteine has a characteristic sulfurous odor; this is normal and does not indicate degradation.
* Nebulized acetylcysteine may cause bronchospasm, particularly in patients with asthma. Coadministration of a bronchodilator may be necessary.
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*This information is intended for healthcare professionals. Always consult the current prescribing information and relevant guidelines for complete details and to ensure patient-specific appropriateness.*
