Please check your internet connection and try again.
# Acetylcysteine
## Overview
Acetylcysteine (NAC) is a mucolytic agent and an antidote for acetaminophen overdose. It is also being investigated for various other potential indications.
## Primary Indications
* **Acetaminophen Overdose:** To prevent or reduce liver toxicity following acetaminophen ingestion.
* **Mucolytic Agent:** To thin and loosen mucus in respiratory conditions such as bronchitis, cystic fibrosis, and COPD.
## Adult Dosing
### Acetaminophen Overdose
The standard protocol involves an initial loading dose followed by subsequent infusions.
* **Oral:** 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses.
* **Intravenous:**
* **Loading Dose:** 150 mg/kg infused over 60 minutes.
* **Second Infusion:** 50 mg/kg infused over 15 minutes (or slower if anaphylactoid reactions occur) after the initial loading dose.
* **Third Infusion:** 100 mg/kg infused over 35 minutes (or slower if anaphylactoid reactions occur) and continued for a total of 20 hours.
* *Note: IV protocols may vary by institution. Some protocols use a 3-bag system or a continuous infusion for the third phase.*
### Mucolytic Agent
* **Inhalation:** 3 mL or 10% solution nebulized every 4 to 12 hours, or 6 mL of 20% solution nebulized every 4 to 12 hours. For patients intolerant to the odor, 1-2 mL of sterile water can be added.
* **Direct Instillation (tracheostomy):** 1-2 mL of 20% solution every 1-4 hours.
## Pediatric Dosing
### Acetaminophen Overdose
Dosing is based on weight, mirroring the adult IV protocol:
* **Intravenous:**
* **Loading Dose:** 150 mg/kg infused over 60 minutes.
* **Second Infusion:** 50 mg/kg infused over 15 minutes (or slower if anaphylactoid reactions occur).
* **Third Infusion:** 100 mg/kg infused over 35 minutes (or slower if anaphylactoid reactions occur) and continued for a total of 20 hours.
* *Note: Concentration limits for IV administration in neonates and infants are important to prevent fluid overload.*
### Mucolytic Agent
* **Inhalation:**
* **<1 year:** 1 mL of 10% solution nebulized every 2 to 6 hours.
* **1-12 years:** 3 mL of 10% solution nebulized every 4 to 12 hours.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is typically recommended, but caution is advised.
* **Hepatic Impairment:** No specific dose adjustment is typically recommended for acetaminophen overdose, but careful monitoring is essential. For mucolytic use, dose adjustments are not usually required.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Active bronchospasm (for inhaled formulations).
## Adverse Effects
* **Common (especially with IV for overdose):** Anaphylactoid reactions (rash, pruritus, urticaria, bronchospasm, dyspnea, angioedema), nausea, vomiting.
* **Less Common:** Bronchorrhea, stomatitis, gastrointestinal upset, drowsiness, fever.
* **Inhaled:** Bronchospasm, nausea, vomiting, stomatitis, rhinorrhea.
## Key Drug Interactions
* **Activated Charcoal:** May adsorb oral acetylcysteine, reducing its efficacy in acetaminophen overdose. Separate administration by at least 1 hour.
* **Nitroglycerin:** Potential for additive hypotensive effects and increased risk of vasodilation.
## Monitoring
* **Acetaminophen Overdose:**
* Liver function tests (ALT, AST, bilirubin, INR) at baseline, 18-24 hours, and 36-48 hours post-ingestion.
* Acetaminophen levels at appropriate intervals to assess efficacy of treatment.
* Renal function.
* Signs of anaphylactoid reactions.
* **Mucolytic Use:**
* Respiratory status, sputum production, and ease of expectoration.
* Signs of bronchospasm.
## Clinical Pearls
* For oral acetaminophen overdose, the antidote must be given within 8 hours of ingestion for maximum efficacy. However, it is still beneficial if given later.
* IV acetylcysteine can be associated with anaphylactoid reactions. Premedication with antihistamines is not routinely recommended but may be considered based on patient history and institutional protocol. Management of these reactions typically involves slowing or temporarily stopping the infusion and administering supportive care.
* The distinct sulfurous odor of acetylcysteine can be unpleasant and may lead to poor compliance, particularly with oral or inhaled formulations. Masking the odor with juice or chocolate syrup may be helpful for oral administration.
* For IV use in acetaminophen overdose, ensure adequate hydration to prevent dehydration and potential renal complications.
***
