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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucus, reducing its viscosity. It also serves as an antidote for acetaminophen overdose by replenishing glutathione stores.
## Primary Indications
* **Acetaminophen Overdose:** To prevent or reduce liver damage.
* **Mucolytic:** To thin respiratory secretions in conditions such as pneumonia, bronchitis, cystic fibrosis, and COPD.
## Adult Dosing
* **Acetaminophen Overdose:**
* **Loading Dose:** 150 mg/kg intravenously (IV) infused over 1 hour.
* **Second Dose:** 50 mg/kg IV infused over 16 hours.
* **Third Dose:** 100 mg/kg IV infused over 16 hours.
* **Alternative Oral Regimen:** 140 mg/kg PO loading dose, followed by 70 mg/kg PO every 4 hours for 17 doses.
* **Maximum IV infusion rate:** 150 mg/kg/hr.
* Dosing may be adjusted based on acetaminophen levels and liver function.
* **Mucolytic:**
* **Nebulized:** 3-5 mL of 20% solution or 6-10 mL of 10% solution every 2-6 hours as needed.
* **Nebulized (minimum frequency):** Every 4-6 hours.
* **Intranasal/Tracheostomy:** 1-2 mL of 20% solution every 1-4 hours.
* **Oral:** 200 mg twice daily for COPD. Higher doses may be used in cystic fibrosis; consult specific protocols.
## Pediatric Dosing
* **Acetaminophen Overdose (IV):** Same as adult dosing (150 mg/kg IV over 1 hour, then 50 mg/kg IV over 16 hours, then 100 mg/kg IV over 16 hours).
* **Acetaminophen Overdose (Oral):** Same as adult oral dosing (140 mg/kg PO loading, then 70 mg/kg PO every 4 hours for 17 doses).
* **Mucolytic (Nebulized):**
* **Infants/Children < 1 year:** 1-2 mL of 20% solution or 2-4 mL of 10% solution every 2-6 hours.
* **Children 1-12 years:** 3-5 mL of 20% solution or 6-10 mL of 10% solution every 2-6 hours.
* **Maximum nebulized dose for children:** 10 mL of 10% solution per treatment.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, however, close monitoring is warranted, especially in acetaminophen overdose.
## Contraindications
* Hypersensitivity to acetylcysteine or other components.
* Acute asthma exacerbations (caution advised when used nebulized).
## Adverse Effects
* **Common (Nebulized):** Bronchospasm, stomatitis, nausea, vomiting.
* **Common (IV for overdose):** Anaphylactoid reactions (rash, pruritus, urticaria, angioedema, bronchospasm, dyspnea, wheezing), nausea, vomiting, tachycardia, hypotension.
* **Rare:** Fever, headache, dizziness.
## Key Drug Interactions
* **Activated Charcoal:** May bind to oral acetylcysteine, reducing absorption. Separate administration by at least 1 hour.
* **Nitroglycerin:** Concurrent use may potentiate hypotensive effects.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels at appropriate time points.
* Liver function tests (AST, ALT, bilirubin, INR, albumin).
* Renal function and electrolytes.
* Glucose levels (especially with IV administration).
* Vital signs and signs of anaphylactoid reaction.
* **Mucolytic:**
* Respiratory status, sputum production and viscosity.
* Pulmonary function tests (if indicated).
* For bronchospasm, especially in asthmatics.
## Clinical Pearls
* For nebulized use, acetylcysteine can have an unpleasant odor, which may decrease compliance.
* Anaphylactoid reactions are common with IV acetylcysteine for overdose and can occur even after prolonged infusion. Antihistamines may be considered prophylactically, and epinephrine should be readily available.
* The effectiveness of acetylcysteine for acetaminophen overdose is time-dependent; prompt initiation is crucial.
* When using nebulized acetylcysteine with bronchodilators, administer the bronchodilator first.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols before making clinical decisions.*
