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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that reduces the viscosity of respiratory tract secretions. It also serves as an antidote for acetaminophen overdose by replenishing hepatic glutathione stores.
## Primary Indications
* **Acetaminophen Overdose:** Treatment to prevent or reduce liver toxicity.
* **Mucolytic:** To thin mucus in respiratory conditions such as COPD, bronchitis, and cystic fibrosis.
## Adult Dosing
* **Acetaminophen Overdose (Oral):**
* **Loading Dose:** 140 mg/kg orally or via nasogastric tube.
* **Maintenance Doses:** 70 mg/kg every 4 hours for 17 doses.
* **Maximum Dose:** Not specified for the total regimen, but individual doses should be calculated based on weight.
* **Acetaminophen Overdose (Intravenous):**
* **Loading Dose:** 150 mg/kg IV infused over 1 hour.
* **Second Infusion:** 50 mg/kg IV infused over 4 hours.
* **Third Infusion:** 100 mg/kg IV infused over 16 hours.
* **Maximum Dose:** Total daily dose depends on the total amount of acetaminophen ingested and the duration of treatment. Standard protocols exist and should be followed.
* **Mucolytic (Nebulization):**
* **Dose:** 3 mL of 10% or 20% solution (300-600 mg) every 2-6 hours as needed.
* **Maximum Dose:** Not explicitly limited per dose, but frequency and duration should be guided by patient response.
* **Mucolytic (Direct Instillation into Tracheostomy Tube):**
* **Dose:** 1-2 mL of 10% or 20% solution (100-400 mg) every 1-4 hours.
## Pediatric Dosing
* **Acetaminophen Overdose (Oral):**
* **Loading Dose:** 140 mg/kg orally or via nasogastric tube.
* **Maintenance Doses:** 70 mg/kg every 4 hours for 17 doses.
* **Maximum Dose:** Not specified for the total regimen.
* **Acetaminophen Overdose (Intravenous):**
* **Loading Dose:** 150 mg/kg IV infused over 1 hour.
* **Second Infusion:** 50 mg/kg IV infused over 4 hours.
* **Third Infusion:** 100 mg/kg IV infused over 16 hours.
* **Maximum Dose:** Total daily dose depends on the total amount of acetaminophen ingested and the duration of treatment. Standard protocols exist and should be followed.
* **Mucolytic (Nebulization):**
* **Dose:** 1 mL of 20% solution (200 mg) or 2 mL of 10% solution (200 mg) every 2-6 hours as needed. May be increased to 5 mL of 10% solution (500 mg) every 2-6 hours.
* **Maximum Dose:** Not explicitly limited per dose, but frequency and duration should be guided by patient response.
## Dose Adjustments
No specific dose adjustments are typically required for hepatic or renal impairment for the mucolytic indication. For acetaminophen overdose, dosing is primarily weight-based.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
## Adverse Effects
* **Common:** Nausea, vomiting, stomatitis, rhinorrhea, bronchospasm (especially with nebulization), rash.
* **Less Common:** Fever, drowsiness, dizziness, blurred vision, urticaria, anaphylactoid reactions.
* **Rare:** Angioedema, hypotension, respiratory distress.
* **Intravenous Administration:** Anaphylactoid reactions can occur, often characterized by rash, urticaria, pruritus, flushing, angioedema, bronchospasm, and hypotension. These are generally managed by slowing the infusion rate and/or administering antihistamines.
## Key Drug Interactions
* **Activated Charcoal:** May adsorb acetylcysteine, reducing its effectiveness in acetaminophen overdose. Administer acetylcysteine at least 1 hour after activated charcoal.
* **Nitroglycerin:** May potentiate the hypotensive effect of nitroglycerin. Monitor blood pressure.
* **Antitussives:** May mask the cough reflex, potentially leading to retained secretions. Use with caution.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels (at appropriate time points, e.g., 4 hours post-ingestion).
* Liver function tests (AST, ALT, bilirubin, INR) at baseline and periodically during treatment.
* Renal function (BUN, creatinine).
* Blood glucose.
* Electrolytes.
* **Mucolytic Use:**
* Respiratory status (e.g., auscultation, oxygen saturation, work of breathing).
* Sputum viscosity and ease of expectoration.
* Signs of bronchospasm.
## Clinical Pearls
* Oral acetylcysteine has an unpleasant sulfurous odor and taste, which can lead to poor patient compliance. It can be mixed with juice or carbonated beverages to improve palatability.
* For intravenous use in acetaminophen overdose, a dedicated antidote protocol should be followed. Early initiation is crucial for efficacy.
* Bronchospasm can occur with nebulized acetylcysteine. Co-administration or pretreatment with a bronchodilator (e.g., albuterol) may be necessary, especially in patients with reactive airway disease.
* Dilute intravenous acetylcysteine for infusion to reduce the risk of phlebitis.
*This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before administering any medication. Dosing and management can vary based on individual patient factors and institutional protocols.*
