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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that loosens thick mucus. It also acts as an antidote for acetaminophen overdose.
## Primary Indications
* Management of acetaminophen overdose.
* Adjunct treatment of significant pulmonary or broncho-pulmonary disease with abnormal mucus secretions (e.g., chronic bronchitis, emphysema, tracheobronchitis, bronchitis, bronchiectasis, cystic fibrosis).
## Adult Dosing
**Acetaminophen Overdose:**
* **Loading Dose:** 150 mg/kg IV infused over 60 minutes.
* **Second Dose:** 50 mg/kg IV infused over 60 minutes, 4 hours after the loading dose.
* **Subsequent Doses:** 100 mg/kg IV infused over 15-60 minutes every 4 hours for a total of 17 doses.
* The total daily dose should not exceed 1200 mg when used as a mucolytic.
* Dosing may be adjusted based on acetaminophen levels and clinical status. Alternative dosing regimens exist; consult specific institutional protocols.
**Pulmonary Disease (Nebulization):**
* 3-5 mL of a 20% solution or 6-10 mL of a 10% solution TID-QID.
* Alternatively, 1-10 g/day may be given.
## Pediatric Dosing
**Acetaminophen Overdose:**
* Same dosing as adults (150 mg/kg IV loading, 50 mg/kg IV second dose, then 100 mg/kg IV every 4 hours for 17 doses).
* Parenteral administration may require dilution to reduce the risk of anaphylactoid reactions in pediatric patients. Consult specific institutional protocols.
**Pulmonary Disease (Nebulization):**
* 5-10 mL of a 10% solution or 3-5 mL of a 20% solution TID-QID.
* Alternatively, 200 mg BID-QID may be given.
## Dose Adjustments
No specific dose adjustments are routinely recommended for renal or hepatic impairment, but caution should be exercised and monitoring is advised.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Acute bronchospasm with nebulized acetylcysteine.
## Adverse Effects
* **Common:** Nausea, vomiting, rash, pruritus, fever, stomatitis.
* **Anaphylactoid Reactions:** Bronchospasm, dyspnea, angioedema, urticaria, hypotension. These are more common with IV administration.
* **Rare:** Hemorrhage (associated with nebulized use in patients with peptic ulcer disease).
## Key Drug Interactions
* **Activated Charcoal:** May adsorb oral acetylcysteine, decreasing its absorption. Separate administration by at least 1 hour.
* **Nitroglycerin:** Concurrent use may potentiate hypotensive effects.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels (at appropriate time points, usually 4 hours post-ingestion).
* Liver function tests (LFTs).
* Prothrombin time (PT).
* Renal function.
* Clinical signs of hepatotoxicity.
* Signs of anaphylactoid reaction (vital signs, respiratory status).
* **Pulmonary Disease:**
* Pulmonary status and secretion clearance.
* Bronchospasm.
## Clinical Pearls
* IV acetylcysteine is highly effective for acetaminophen overdose, especially when initiated within 8-10 hours of ingestion.
* Anaphylactoid reactions are a significant concern with IV acetylcysteine; monitor patients closely and have emergency equipment readily available. Pretreatment with an H1 antihistamine may be considered.
* Nebulized acetylcysteine can cause bronchospasm; use with caution in patients with asthma or reactive airway disease and consider co-administration of a bronchodilator.
* The odor of acetylcysteine is unpleasant and can cause nausea and vomiting.
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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.*
