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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucus, reducing its viscosity. It is also an antidote for acetaminophen overdose by replenishing glutathione stores.
## Primary Indications
* **Acetaminophen Overdose:** Treatment to prevent or mitigate liver damage.
* **Mucolytic Agent:** To reduce mucus buildup in respiratory conditions such as cystic fibrosis, chronic obstructive pulmonary disease (COPD), and bronchitis.
## Adult Dosing
### Acetaminophen Overdose
* **Oral:** Loading dose of 140 mg/kg, followed by 70 mg/kg every 4 hours for 17 doses (total 72-hour treatment). Maximum dose not typically specified, but large volumes can be a concern.
* **Intravenous (IV):** Protocol-dependent, but a common regimen involves an initial bolus of 150 mg/kg over 1 hour, followed by 12.5 mg/kg/hour for 4 hours, then 6.25 mg/kg/hour for 16 hours. Higher initial doses may be used in severe cases.
* *Note: Specific IV protocols vary significantly by institution. Always consult local guidelines.*
### Mucolytic Agent
* **Oral/Inhalation:** Typically 200 mg to 400 mg two to three times daily.
* **Intravenous (IV):** Typically 150 mg/kg/day in divided doses for severe conditions, but this is less common than inhaled or oral routes.
* **Nebulization:** 1-10 mL of a 10-20% solution every 2-6 hours.
## Pediatric Dosing
### Acetaminophen Overdose
* **Oral:** Same as adult dosing: 140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses.
* **Intravenous (IV):** Same as adult dosing, adjusted for weight. Consult local protocols.
* *Note: Pediatric protocols for IV acetylcysteine are highly specific and institution-dependent.*
### Mucolytic Agent
* **Nebulization:** Generally 1-10 mL of a 10-20% solution every 2-6 hours. Dosing is often based on age and weight, and some protocols recommend lower concentrations for younger children.
* **Oral:** Dosing varies by age and indication. For example, 50-100 mg every 3-4 hours or 200 mg twice daily for children over 2 years.
## Dose Adjustments
* **Renal/Hepatic Impairment:** No specific dose adjustments are typically required for acetaminophen overdose management. For mucolytic use, caution may be warranted, but specific adjustments are not usually defined.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Active gastrointestinal bleeding (for oral administration, due to potential for emesis).
## Adverse Effects
* **Common:** Nausea, vomiting, stomatitis, diarrhea (oral/IV). Bronchospasm, bronchoconstriction (inhalation). Rash, pruritus, urticaria.
* **Serious:** Anaphylactoid reactions (can be severe, especially with rapid IV infusion), angioedema, respiratory distress. Bronchospasm.
## Key Drug Interactions
* **Activated Charcoal:** Can adsorb acetylcysteine, reducing its efficacy in acetaminophen overdose. Separate administration by at least 1 hour.
* **Nitroglycerin:** Potentiation of vasodilatory effects may occur. Monitor blood pressure.
## Monitoring
* **Acetaminophen Overdose:**
* **Acetaminophen and APAP metabolite levels:** To assess efficacy of antidote and guide duration of therapy.
* **Liver function tests (LFTs):** AST, ALT, bilirubin, INR to monitor for hepatotoxicity.
* **Renal function:** BUN, creatinine.
* **Glucose:** Particularly with IV administration.
* **Mucolytic Use:**
* Respiratory status, sputum viscosity and volume.
* Bronchospasm.
## Clinical Pearls
* The effectiveness of acetylcysteine in acetaminophen overdose is greatest when initiated within 8-10 hours of ingestion.
* IV acetylcysteine has a higher risk of anaphylactoid reactions than oral. Premedication with antihistamines may be considered.
* For nebulized acetylcysteine, bronchodilators should be administered first if the patient has reactive airway disease to minimize bronchospasm.
* N-acetylcysteine can have an unpleasant odor.
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*Disclaimer: This information is intended for educational purposes and does not substitute for professional medical advice. Always verify the most current prescribing information and local protocols before initiating treatment.*
