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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucoproteins, decreasing viscosity. It is also an antidote for acetaminophen overdose by replenishing glutathione stores.
## Primary Indications
* **Acetaminophen overdose:** Antidote.
* **Mucolytic agent:** To thin mucus in conditions such as bronchitis, COPD, cystic fibrosis, and pneumonia.
## 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 (may be repeated for 24 hours if acetaminophen levels remain elevated or hepatotoxicity is suspected).
* **Oral Dosing:** 17 doses of 140 mg/kg (maximum 200 mg/kg/dose) followed by 70 mg/kg (maximum 100 mg/kg/dose) every 4 hours for a total of 72 hours.
### Mucolytic Agent
* **Nebulized:** 1-10 mL of 20% solution or 2-20 mL of 10% solution every 2-6 hours as needed.
* **Oral:** 200 mg (standard strength) to 600 mg (extended-release) PO BID or TID.
## Pediatric 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 (may be repeated for 24 hours if acetaminophen levels remain elevated or hepatotoxicity is suspected).
* **Oral Dosing:** 17 doses of 140 mg/kg (maximum 200 mg/kg/dose) followed by 70 mg/kg (maximum 100 mg/kg/dose) every 4 hours for a total of 72 hours.
### Mucolytic Agent
* **Nebulized:** 1-10 mL of 20% solution or 2-20 mL of 10% solution every 2-6 hours as needed.
* **Oral:** 600 mg PO BID or TID (dose often based on weight, e.g., 10-20 mg/kg/day divided BID-TID; maximum 600 mg/day).
## Dose Adjustments
No specific dose adjustments are routinely recommended for hepatic or renal impairment, though caution is advised.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
## Adverse Effects
* **IV Administration:** Anaphylactoid reactions (rash, urticaria, pruritus, angioedema, bronchospasm, dyspnea, hypotension) are common. Flushing, nausea, vomiting, and fever can also occur.
* **Nebulized:** Bronchospasm, nausea, vomiting, stomatitis, rhinorrhea.
* **Oral:** Nausea, vomiting, diarrhea, rash.
## Key Drug Interactions
* **Activated Charcoal:** May reduce the absorption of orally administered acetylcysteine.
* **Nitroglycerin:** May potentiate vasodilation and hypotension.
## Monitoring
* **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests (ALT, AST, bilirubin, INR), blood glucose, and renal function.
* **Mucolytic Use:** Respiratory status, sputum production, and potential for bronchospasm.
## Clinical Pearls
* The smell of acetylcysteine can be unpleasant; masking with juice or flavored preparations may improve tolerability for oral administration.
* For IV administration in acetaminophen overdose, the protocol should be initiated as soon as possible after ingestion, ideally within 8 hours, for maximum efficacy.
* Nebulized acetylcysteine can sometimes exacerbate bronchospasm; co-administration with a bronchodilator may be beneficial.
* For IV use, dilute to a concentration of no more than 10 mg/mL to reduce the risk of anaphylactoid reactions.
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*This information is intended for clinical use and does not replace professional judgment. Always verify current prescribing information with the official drug product labeling and institutional protocols.*
