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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucus, reducing its viscosity. It is also an antidote for acetaminophen overdose by replenishing glutathione stores.
## Primary Indications
* **Acetaminophen Overdose:** To prevent or treat hepatotoxicity.
* **Mucolytic:** To thin respiratory secretions in conditions like cystic fibrosis, chronic obstructive pulmonary disease (COPD), and pneumonia.
## Adult Dosing
### Acetaminophen Overdose
* **Oral:** Initial loading dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses.
* **Intravenous (IV):**
* **Standard Protocol:** 150 mg/kg IV over 1 hour, followed by 12.5 mg/kg/hour IV for 4 hours, then 6.25 mg/kg/hour IV for 16 hours. Total duration is 21 hours.
* **Alternative Protocol:** 200 mg/kg IV over 4 hours.
* **Mucolytic:**
* **Nebulized:** 1-10 mL of 10% or 20% solution every 2-6 hours as needed.
* **Oral (Effervescent Tablet):** 200 mg two to three times daily.
## Pediatric Dosing
### Acetaminophen Overdose
* **Oral:** Same as adult: 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses.
* **Intravenous (IV):** Same as adult: 150 mg/kg IV over 1 hour, then 12.5 mg/kg/hour IV for 4 hours, then 6.25 mg/kg/hour IV for 16 hours.
* **Mucolytic:**
* **Nebulized:** 1-3 mL of 10% or 20% solution every 2-6 hours as needed. Dose may be adjusted based on patient tolerance and response.
## Dose Adjustments
* **Hepatic Impairment:** No specific dose adjustment for acetaminophen overdose; however, close monitoring is crucial due to increased risk of hepatotoxicity.
* **Renal Impairment:** No specific dose adjustment for acetaminophen overdose; however, caution and close monitoring are advised.
* **Hepatic Impairment (Mucolytic):** No specific dose adjustment.
## Contraindications
* Hypersensitivity to acetylcysteine.
* Active bronchospasm (for nebulized form).
## Adverse Effects
* **Anaphylactoid Reactions:** Bronchospasm, angioedema, rash, pruritus, urticaria. More common with IV administration.
* **Gastrointestinal:** Nausea, vomiting, diarrhea (especially with oral administration).
* **Respiratory:** Bronchorrhea, rhinorrhea.
* **Other:** Fever, headache.
## Key Drug Interactions
* **Activated Charcoal:** Decreases absorption of oral acetylcysteine. If both are indicated, separate administration by at least 1 hour.
* **Nitroglycerin:** IV acetylcysteine may potentiate the hypotensive effects of nitroglycerin.
## Monitoring
* **Acetaminophen Overdose:**
* **Serum Acetaminophen Levels:** To assess the need for continued treatment.
* **Liver Function Tests (LFTs):** AST, ALT, bilirubin, PT/INR.
* **Renal Function:** BUN, creatinine.
* **Electrolytes.**
* **Clinical signs of hepatotoxicity.**
* **Mucolytic:**
* Respiratory status (e.g., breath sounds, oxygen saturation, work of breathing).
* Frequency and severity of bronchospasm.
## Clinical Pearls
* For IV acetylcysteine in acetaminophen overdose, consider pre-treatment with an antihistamine to reduce the incidence of anaphylactoid reactions.
* The smell of acetylcysteine is unpleasant (sulfurous); this is normal and does not indicate degradation.
* Ensure adequate hydration when using acetylcysteine as a mucolytic.
* The efficacy of nebulized acetylcysteine may be reduced in patients with severe airway hyperreactivity or bronchospasm.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols for definitive guidance.
