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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucoproteins, decreasing mucus viscosity. It is also an antidote for acetaminophen overdose.
## Primary Indications
* **Acetaminophen Overdose:** Treatment of acetaminophen toxicity.
* **Mucolytic:** Adjunct therapy in patients with abnormal secretion of viscid or excessively tenacious mucus, such as in chronic obstructive pulmonary disease (COPD), bronchitis, cystic fibrosis, and tracheostomy care.
## Adult Dosing
### Acetaminophen Overdose (Oral or IV)
Protocols vary. A common IV protocol involves a loading dose followed by maintenance doses. For example:
* **Loading Dose:** 150 mg/kg IV infused over 1 hour.
* **Second Dose:** 50 mg/kg IV infused over 4 hours.
* **Third Dose:** 100 mg/kg IV infused over 16 hours.
* **Maximum Dose:** Total daily dose should not exceed 7.5 g for IV administration.
* **Oral Dosing:** Can also be administered orally, often in a 5% solution, with doses typically starting at 140 mg/kg.
### Mucolytic (Inhaled)
* **Nebulization:** 3 mL of a 20% solution or 6 mL of a 10% solution administered by nebulization every 3-4 hours.
* **Direct Instillation:** 1-2 mL of a 10-20% solution into the tracheostomy tube every 1-4 hours.
## Pediatric Dosing
### Acetaminophen Overdose (IV)
Dosing is the same as adults based on weight (150 mg/kg IV over 1 hour, then 50 mg/kg IV over 4 hours, then 100 mg/kg IV over 16 hours).
### Acetaminophen Overdose (Oral)
* **Loading Dose:** 140 mg/kg orally.
* **Subsequent Doses:** 70 mg/kg orally every 4 hours for 17 doses.
### Mucolytic (Inhaled)
* **Nebulization:** Dosing is weight-based or by age, and specific concentrations. A common recommendation is 1 mL of a 20% solution or 2 mL of a 10% solution via nebulizer every 2-6 hours. Refer to specific institutional protocols for precise pediatric nebulized dosing.
## Dose Adjustments
No dose adjustment is typically needed for renal or hepatic impairment, however, caution is advised in severe impairment.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Acute asthmatic attacks (for inhaled form).
## Adverse Effects
* **Common:** Nausea, vomiting (especially with oral form), stomatitis, rash, urticaria.
* **Less Common:** Bronchospasm, anaphylactoid reactions, fever, chills, rhinorrhea, drowsiness, hypertension, tachycardia, dyspnea.
* **Rare:** Hemorrhage (associated with oral administration).
## Key Drug Interactions
* **Activated Charcoal:** May bind to acetylcysteine and reduce its absorption, especially with oral overdose treatment.
* **Nitroglycerin:** Concomitant use may potentiade the hypotensive effect of nitroglycerin.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels (timing is critical for nomogram interpretation).
* Liver function tests (LFTs).
* Prothrombin time (PT).
* Renal function.
* Electrolytes.
* **Mucolytic:**
* Pulmonary status (respiratory rate, oxygen saturation, lung sounds).
* Ability to clear secretions.
* Bronchospasm.
## Clinical Pearls
* For inhaled acetylcysteine, patients may experience increased bronchospasm. Co-administration of a bronchodilator is often recommended.
* The odor of acetylcysteine is strong and unpleasant, which can contribute to nausea and vomiting, particularly with oral administration.
* The efficacy of acetylcysteine for acetaminophen overdose is highest when initiated within 8-10 hours of ingestion.
* For IV administration in acetaminophen overdose, use a non-PVC IV bag and administration set if possible to minimize potential leaching.
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*Please verify current prescribing information for specific details and institutional protocols.*
