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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent used to break down thick mucus in respiratory conditions. It is also the antidote for acetaminophen overdose.
## Primary Indications
* **Acetaminophen Overdose:** To prevent or reduce liver toxicity.
* **Mucolytic:** To thin mucus in conditions such as pneumonia, bronchitis, cystic fibrosis, and chronic obstructive pulmonary disease (COPD).
## Adult Dosing
* **Acetaminophen Overdose (Intravenous):**
* **Loading Dose:** 150 mg/kg IV over 1 hour.
* **Second Infusion:** 50 mg/kg IV over 16 hours.
* **Third Infusion (if needed):** 50 mg/kg IV over 16 hours.
* Maximum infusion rate is typically 12.5 g/hour.
* Protocols may vary; consult local guidelines.
* **Acetaminophen Overdose (Oral):**
* **Loading Dose:** 140 mg/kg PO.
* **Subsequent Doses:** 70 mg/kg PO every 4 hours for 17 doses (total of 18 doses).
* Administer activated charcoal if ingestion was recent.
* **Mucolytic (Inhaled):**
* 3-10 mL of a 10% or 20% solution nebulized every 2-6 hours. Alternatively, 1-2 mL of a 20% solution or 2-4 mL of a 10% solution tid-qid.
* Dosing may be guided by institutional protocol.
## Pediatric Dosing
* **Acetaminophen Overdose (Intravenous):**
* Dosing is the same as adult: 150 mg/kg IV over 1 hour, followed by 50 mg/kg IV over 16 hours, repeated for a third infusion if necessary.
* **Acetaminophen Overdose (Oral):**
* Dosing is the same as adult: 140 mg/kg PO, followed by 70 mg/kg PO every 4 hours for 17 doses.
* **Mucolytic (Inhaled):**
* Dosing is typically weight-based: 3-10 mL of a 10% or 20% solution nebulized every 2-6 hours, or 1-2 mL of a 20% solution or 2-4 mL of a 10% solution tid-qid.
* Dosing should be guided by institutional protocol.
## Dose Adjustments
* No specific dose adjustments are typically required for hepatic or renal impairment, but caution is advised in severe cases due to potential accumulation and increased risk of adverse effects.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Active inflammation of the esophagus or stomach (for oral administration).
## Adverse Effects
* **Intravenous:** Anaphylactoid reactions (rash, urticaria, angioedema, bronchospasm, hypotension), flushing, pruritus, fever, nausea, vomiting, tachycardia.
* **Oral:** Nausea, vomiting, diarrhea, stomatitis.
* **Inhaled:** Bronchospasm, bronchoconstriction, increased sputum volume, rhinorrhea, nausea, vomiting, stomatitis.
## Key Drug Interactions
* **Activated Charcoal:** May adsorb oral acetylcysteine, reducing its absorption. Administer activated charcoal at least 1 hour before or after oral acetylcysteine.
* **Nitroglycerin:** Concurrent use may potentiate the hypotensive effect of nitroglycerin.
## Monitoring
* **Acetaminophen Overdose:**
* Liver function tests (ALT, AST, bilirubin, INR) every 24 hours, especially within the first 72 hours.
* Acetaminophen levels to assess the need for continued treatment.
* Renal function and electrolytes.
* **Mucolytic:**
* Respiratory status (breath sounds, oxygen saturation, work of breathing).
* Sputum characteristics.
* Bronchospasm.
## Clinical Pearls
* For IV administration in acetaminophen overdose, prompt initiation is crucial, ideally within 8 hours of ingestion.
* Anaphylactoid reactions are common with IV acetylcysteine; monitor closely and be prepared to manage symptoms. Pre-treatment with antihistamines and/or corticosteroids may be considered in some protocols.
* For inhaled acetylcysteine, co-administration with a bronchodilator may be necessary to prevent or manage bronchospasm.
* The smell of acetylcysteine is unpleasant (sulfurous); this can contribute to nausea and vomiting, especially with oral administration.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional guidelines before administering any medication.*
