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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucoproteins, reducing the viscosity of mucus. It is also an antidote for acetaminophen overdose.
## Primary Indications
* **Acetaminophen overdose:** To prevent or reduce liver toxicity.
* **Mucolytic:** To thin respiratory secretions in conditions such as bronchitis, pneumonia, and COPD.
## Adult Dosing
**Acetaminophen Overdose:**
* **Loading dose:** 150 mg/kg IV infused over 1 hour.
* **Second dose:** 50 mg/kg IV infused over 16 hours.
* **Third dose:** 100 mg/kg IV infused over 16 hours.
* The total duration of therapy is typically 21 hours. Dosing may vary based on acetaminophen levels and clinical response, and specific IV protocols should be followed. An oral regimen is also available, with doses often administered every 4 hours.
**Mucolytic:**
* **Inhalation:** 1-10 mL of a 10% or 20% solution via nebulizer every 2-6 hours.
* **Oral:** 200 mg to 400 mg twice daily or three times daily.
## Pediatric Dosing
**Acetaminophen Overdose:**
* Dosing is the same as adults on a mg/kg basis.
* **Loading dose:** 150 mg/kg IV infused over 1 hour.
* **Second dose:** 50 mg/kg IV infused over 16 hours.
* **Third dose:** 100 mg/kg IV infused over 16 hours.
* Dosing may vary based on acetaminophen levels and clinical response, and specific IV protocols should be followed. An oral regimen is also available.
**Mucolytic:**
* **Inhalation:**
* 1 month to 2 years: 1-2 mL of a 10% or 20% solution via nebulizer every 2-6 hours.
* 2 years and older: 1-10 mL of a 10% or 20% solution via nebulizer every 2-6 hours.
* **Oral:** 50 mg/kg twice daily or three times daily, not to exceed adult doses.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment for the mucolytic indication. For acetaminophen overdose, dosing is based on body weight and acetaminophen levels.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Active hemorrhage (for oral administration, though risk is low).
## Adverse Effects
* **IV administration:** Anaphylactoid reactions (rash, urticaria, pruritus, bronchospasm, angioedema), hypotension, tachycardia, fever, nausea, vomiting.
* **Inhalation:** Bronchospasm, rhinorrhea, nausea, vomiting, stomatitis.
* **Oral:** Nausea, vomiting, diarrhea, abdominal pain.
## Key Drug Interactions
* **Activated charcoal:** May bind to oral acetylcysteine and reduce its absorption.
* **Nitroglycerin:** May potentiate hypotensive effects.
## Monitoring
* **Acetaminophen Overdose:** Serial serum acetaminophen levels, liver function tests (AST, ALT, bilirubin), prothrombin time, glucose, electrolytes, and renal function. Monitor for signs of anaphylactoid reaction during IV infusion.
* **Mucolytic:** Pulmonary status, sputum viscosity, and frequency of exacerbations.
## Clinical Pearls
* When administering IV acetylcysteine for acetaminophen overdose, anticipate and manage potential anaphylactoid reactions. Premedication with an antihistamine may be considered by some protocols.
* For inhaled acetylcysteine, bronchodilators should be administered prior to nebulization if the patient has reactive airway disease to minimize bronchospasm.
* The effectiveness of acetylcysteine in acetaminophen overdose is time-dependent; earlier treatment leads to better outcomes.
* Ensure adequate hydration when using acetylcysteine as a mucolytic.
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*This information is intended for healthcare professionals and does not replace professional clinical judgment or the full prescribing information. Always verify current prescribing information and consult with a qualified healthcare provider.*
