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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucus, decreasing its viscosity. 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 like chronic bronchitis, emphysema, cystic fibrosis, and pneumonia.
## Adult Dosing
### Acetaminophen Overdose
**IV Dosing:** Administered as a loading dose followed by a maintenance infusion. Protocols vary, but a common regimen includes:
* **Loading Dose:** 150 mg/kg IV over 1 hour.
* **Second Dose:** 50 mg/kg IV over the next 1 hour.
* **Third Dose:** 100 mg/kg IV infused over 16 hours.
* **Maximum Total Dose:** Typically not specified for overdose treatment, as it's based on acetaminophen levels and time since ingestion.
**Oral Dosing:**
* **Loading Dose:** 140 mg/kg PO.
* **Subsequent Doses:** 70 mg/kg PO every 4 hours for 17 doses (total of 18 doses).
* **Maximum Dose:** 140 mg/kg per dose.
### Mucolytic
**Nebulization:** 10% solution: 3-5 mL via nebulizer every 3-4 hours. 20% solution: 3-5 mL via nebulizer every 6-8 hours.
**Direct Instillation:** 1-2 mL of 10-20% solution into tracheostomy or endotracheal tube every 1-4 hours as needed.
## Pediatric Dosing
### Acetaminophen Overdose
**IV Dosing:** Similar to adults, weight-based. Protocols may differ slightly for neonates and infants; consult specific hospital protocols.
* **Loading Dose:** 150 mg/kg IV over 1 hour.
* **Second Dose:** 50 mg/kg IV over the next 1 hour.
* **Third Dose:** 100 mg/kg IV infused over 16 hours.
**Oral Dosing:**
* **Loading Dose:** 140 mg/kg PO.
* **Subsequent Doses:** 70 mg/kg PO every 4 hours for 17 doses.
* **Maximum Dose:** 140 mg/kg per dose.
### Mucolytic
Dosing is based on the concentration and volume, typically 10% or 20% solution.
**Nebulization:**
* **10% solution:** 1-3 mL via nebulizer every 3-4 hours.
* **20% solution:** 1-2 mL via nebulizer every 6-8 hours.
* Dosing can be adjusted based on patient response and tolerance.
## Dose Adjustments
No dose adjustments are typically required for hepatic or renal impairment for overdose treatment, as the goal is to saturate metabolic pathways. For mucolytic use, adjustments are based on patient response and tolerance.
## Contraindications
* Hypersensitivity to acetylcysteine.
* Active hemorrhage (caution advised for mucolytic use).
## Adverse Effects
**Common:** Nausea, vomiting, stomatitis, rhinorrhea, bronchospasm, rash.
**Less Common/Severe:** Anaphylactoid reactions (especially with IV administration), urticaria, angioedema, fever, chills.
## Key Drug Interactions
* **Activated Charcoal:** Can adsorb oral acetylcysteine, reducing its efficacy. Administer acetylcysteine at least 1 hour after activated charcoal.
* **Nitroglycerin:** May potentiate hypotensive effects.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels (at appropriate time points).
* Liver function tests (AST, ALT, bilirubin, INR).
* Renal function.
* Glucose levels.
* Signs of anaphylactoid reaction (vital signs, rash, wheezing).
* **Mucolytic Use:**
* Respiratory status (lung sounds, oxygen saturation, work of breathing).
* Bronchospasm.
## Clinical Pearls
* For acetaminophen overdose, treatment should be initiated as soon as possible, ideally within 8 hours of ingestion.
* Intravenous acetylcysteine administration can cause anaphylactoid reactions; monitor closely and have resuscitation equipment readily available. Slowing the infusion rate may help manage mild reactions.
* Oral acetylcysteine has a very unpleasant sulfurous odor and taste, which can lead to vomiting. Antiemetics may be necessary.
* When used as a mucolytic, acetylcysteine can induce bronchospasm in susceptible individuals, particularly asthmatics. Co-administration with a bronchodilator is often recommended.
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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 institutional protocols before making clinical decisions.
