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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent and an antidote for acetaminophen overdose. It acts by breaking disulfide bonds in mucoproteins, decreasing mucus viscosity. As an antidote, it replenishes glutathione stores depleted by acetaminophen metabolism.
## Primary Indications
* **Acetaminophen Overdose:** Treatment to prevent or reduce liver toxicity.
* **Mucolytic:** To reduce the viscosity of tenacious mucus secretions in conditions like cystic fibrosis, COPD, and pneumonia.
## Adult Dosing
**Acetaminophen Overdose:**
* **Oral:**
* Loading dose: 140 mg/kg.
* Maintenance: 70 mg/kg every 4 hours for 17 doses.
* Maximum dose: Typically not specified, but large single doses are given.
* **Intravenous (IV):**
* Loading dose: 150 mg/kg infused over 1 hour.
* Second infusion: 50 mg/kg infused over 4 hours.
* Third infusion: 100 mg/kg infused over 16 hours.
* Maximum infusion rate for loading dose: 150 mg/kg/hr.
* *Note: IV dosing protocols can vary; consult local institutional guidelines.*
**Mucolytic:**
* **Inhaled:** 3 mL to 5 mL of a 10% or 20% solution via nebulizer every 2 to 6 hours as needed.
## 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, then 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours).
* *Note: IV dosing protocols can vary; consult local institutional guidelines.*
**Mucolytic:**
* **Inhaled:** 1 mL to 3 mL of a 10% or 20% solution via nebulizer every 2 to 6 hours as needed. Premature infants may require smaller volumes.
## Dose Adjustments
No specific dose adjustments are generally required for renal or hepatic impairment when used as an antidote for acetaminophen overdose, as the goal is to replete glutathione systemically. For mucolytic use, dose adjustments are typically based on patient response and tolerance.
## Contraindications
* Hypersensitivity to acetylcysteine.
## Adverse Effects
* **Common (Oral/IV):** Nausea, vomiting, diarrhea.
* **Common (IV):** Anaphylactoid reactions (rash, pruritus, bronchospasm, angioedema), flushing, hypotension.
* **Common (Inhaled):** Bronchospasm, stomatitis, rhinorrhea, nausea.
* **Rare:** Anaphylaxis.
## Key Drug Interactions
* **Activated Charcoal:** Reduces absorption of oral acetylcysteine. If activated charcoal has been administered for acetaminophen overdose, it should be held for at least 1 hour after the oral acetylcysteine dose.
* **Nitroglycerin:** May potentiate hypotensive effects. Monitor blood pressure closely.
## Monitoring
* **Acetaminophen Overdose:**
* **Liver Function Tests (LFTs):** ALT, AST, bilirubin, INR (baseline and periodically; typically every 24 hours).
* **Acetaminophen Levels:** To assess efficacy of treatment and determine duration.
* **Renal Function:** BUN, creatinine.
* **Mucolytic:**
* Pulmonary status (e.g., lung auscultation, ease of expectoration).
* Bronchospasm.
## Clinical Pearls
* For acetaminophen overdose, IV administration is preferred if oral intake is unreliable or vomiting is severe.
* Administer IV acetylcysteine with caution in patients with asthma due to the risk of bronchospasm. Pretreatment with a bronchodilator may be considered.
* The characteristic sulfurous odor of acetylcysteine may be unpleasant; masking with juice or other beverages can improve palatability for oral administration.
* When used as a mucolytic, hydration is crucial to maximize its effectiveness.
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**Disclaimer:** This information is intended for clinical decision-making by healthcare professionals. It is not a substitute for professional medical advice. Always consult the most current prescribing information and institutional protocols before initiating or modifying drug therapy.
