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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that decreases the viscosity of respiratory tract secretions. It is also an antidote for acetaminophen overdose.
## Primary Indications
* Adjunct to appropriate antibiotic therapy in patients with pneumonia, bronchitis, tracheitis, epiglottitis, and otitis media.
* Antidote for acetaminophen overdose.
* Adjunct to bronchodilator therapy in patients with chronic obstructive pulmonary disease (COPD), cystic fibrosis, or bronchiectasis.
## Adult Dosing
* **Acetaminophen Overdose:**
* **Oral:** Loading dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses.
* **Intravenous (IV):** 150 mg/kg over 1 hour, followed by 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours. Maximum dose may vary by protocol.
* **Mucolytic:** 3 mL of 20% solution or 6 mL of 10% solution inhaled via nebulizer every 3-4 hours as needed. Higher doses may be used in specific conditions like cystic fibrosis, per local protocol.
## Pediatric Dosing
* **Acetaminophen Overdose:**
* **Oral:** Same as adult dosing (140 mg/kg loading, then 70 mg/kg every 4 hours for 17 doses).
* **Intravenous (IV):** Same as adult dosing (150 mg/kg over 1 hour, then 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours). Dosing may be adjusted based on weight and serum acetaminophen levels.
* **Mucolytic:** 10% solution inhaled via nebulizer. Dosing typically 1-2 mL every 2-6 hours, or 6-12 months: 1 mL tid-qid; 1-12 years: 2 mL tid-qid; >12 years: 3 mL tid-qid. Dose may be adjusted based on clinical response and local protocol.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment for the mucolytic indication. For acetaminophen overdose, dosing is weight-based and guided by acetaminophen/metabolite levels.
## Contraindications
Hypersensitivity to acetylcysteine.
## Adverse Effects
* **Inhaled:** Bronchospasm, stomatitis, nausea, vomiting, rhinorrhea.
* **IV (for overdose):** Anaphylactoid reactions (urticaria, angioedema, bronchospasm), rash, pruritus, flushing, tachycardia, hypotension.
## Key Drug Interactions
* **Activated Charcoal:** May adsorb oral acetylcysteine, reducing its effectiveness in acetaminophen overdose. Administer acetylcysteine at least 1 hour after activated charcoal.
* **Nitroglycerin:** May potentiate the vasodilatory effects of nitroglycerin, leading to hypotension.
## Monitoring
* **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests (LFTs), prothrombin time (PT), international normalized ratio (INR), glucose.
* **Mucolytic:** Respiratory status, frequency and consistency of sputum, signs of bronchospasm.
## Clinical Pearls
* The smell of acetylcysteine is often described as unpleasant (sulfurous).
* For IV administration in acetaminophen overdose, premedication with an H1 antagonist may be considered to reduce the incidence of anaphylactoid reactions.
* Ensure adequate hydration when administering acetylcysteine orally.
* If bronchospasm occurs with inhaled acetylcysteine, consider co-administration with a bronchodilator.
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*Disclaimer: This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines for complete details, including specific contraindications, warnings, precautions, and potential drug interactions. Dosing can vary based on patient factors and institutional protocols.*
