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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucoproteins, reducing viscosity. It is also an antidote for acetaminophen overdose.
## Primary Indications
* **Acetaminophen Overdose:** To prevent or reduce liver toxicity.
* **Mucolytic:** Adjunct therapy for conditions with excessive or thick mucus secretions (e.g., bronchitis, COPD, cystic fibrosis).
## Adult Dosing
### Acetaminophen Overdose:
* **Oral:**
* Loading dose: 140 mg/kg as a single dose.
* Maintenance dose: 70 mg/kg every 4 hours for 17 doses.
* Maximum single dose: 1000 mg.
* **Intravenous (IV):**
* Loading dose: 150 mg/kg over 1 hour.
* Second dose: 50 mg/kg over the next 4 hours.
* Third dose: 100 mg/kg over the next 16 hours.
* *Note:* Specific IV protocols may vary; consult local guidelines.
### Mucolytic:
* **Inhaled:** 1-10 mL of 10% or 20% solution, or 3-5 mL of 20% solution, nebulized every 2-6 hours. Dosing is often guided by patient response and local protocol.
* **Oral:** 200 mg to 400 mg two to four times daily.
## Pediatric Dosing
### Acetaminophen Overdose:
* **Oral:** Same as adult dosing (140 mg/kg loading, 70 mg/kg every 4 hours for 17 doses).
* **Intravenous (IV):** Same as adult dosing (150 mg/kg over 1 hour, 50 mg/kg over 4 hours, 100 mg/kg over 16 hours).
### Mucolytic:
* **Inhaled:**
* **< 1 year:** 1-2 mL of 10% solution, nebulized every 2-6 hours.
* **1-2 years:** 2-4 mL of 10% solution, or 1-2 mL of 20% solution, nebulized every 2-6 hours.
* **> 2 years:** 3-5 mL of 20% solution, or 5-10 mL of 10% solution, nebulized every 2-6 hours. Dosing is often guided by patient response and local protocol.
* **Oral:** 50 mg/kg to 100 mg/kg two to four times daily. Maximum dose 600 mg/day.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment for the mucolytic indication. For acetaminophen overdose, dosing is weight-based and not adjusted for organ dysfunction.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Active hemorrhage (for inhaled use, though benefit may outweigh risk in select cases).
## Adverse Effects
* **Inhaled:** Bronchospasm, rhinorrhea, stomatitis, nausea, vomiting.
* **Oral:** Nausea, vomiting, diarrhea, rash.
* **Intravenous (IV):** Anaphylactoid reactions (flushing, pruritus, rash, urticaria, tachycardia, hypotension), bronchospasm, angioedema.
## Key Drug Interactions
* **Activated Charcoal:** May bind to oral acetylcysteine, reducing absorption. Separate administration by at least 1 hour.
* **Nitroglycerin:** Potential for additive hypotensive effects.
## Monitoring
* **Acetaminophen Overdose:** Liver function tests (ALT, AST, bilirubin, INR) every 24 hours until normalized. Serum acetaminophen levels. Clinical signs of liver injury.
* **Mucolytic:** Respiratory status, sputum viscosity and volume, bronchospasm.
## Clinical Pearls
* For IV administration in acetaminophen overdose, reactions resembling anaphylaxis are common but are often related to the rate of infusion and can be managed with slowed infusion and antihistamines. True anaphylaxis is less common.
* When nebulizing, acetylcysteine may cause bronchospasm, particularly in asthmatics. Co-administration of a bronchodilator may be necessary.
* Freshly prepared solutions are preferred for nebulization.
* The odor of sulfur is characteristic and may be unpleasant for patients.
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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 any treatment decisions.
