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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucoproteins, reducing the viscosity of respiratory and mucus secretions. It is also an antidote for acetaminophen overdose by replenishing hepatic glutathione stores.
## Primary Indications
* **Acetaminophen overdose:** To prevent or reduce liver damage.
* **Mucolytic:** To thin mucus secretions in conditions such as chronic bronchitis, emphysema, and cystic fibrosis.
## Adult Dosing
**Acetaminophen Overdose:**
* **IV Administration:**
* **Loading Dose:** 150 mg/kg 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.
* *Note:* Specific infusion rates are crucial and often dictated by local protocols. Total duration is typically 20-21 hours.
* **Oral Administration:**
* **Loading Dose:** 140 mg/kg PO.
* **Subsequent Doses:** 70 mg/kg PO every 4 hours for 17 doses (total of 18 doses).
* *Note:* Oral administration is associated with a higher incidence of nausea and vomiting. Antiemetics may be required.
**Mucolytic:**
* **Inhaled:** 3 mL to 5 mL of a 20% solution or 6 mL to 10 mL of a 10% solution administered via nebulizer every 4 to 12 hours.
## Pediatric Dosing
**Acetaminophen Overdose (IV):**
* Dosing is the same as adults: 150 mg/kg IV over 1 hour, then 50 mg/kg IV over 16 hours, then 100 mg/kg IV over 16 hours.
* *Note:* Safe and effective use in children under 2 years of age for acetaminophen overdose is less well-established, but typically the adult dosing regimen is used.
**Acetaminophen Overdose (Oral):**
* Dosing is the same as adults: 140 mg/kg PO loading dose, followed by 70 mg/kg PO every 4 hours for 17 doses.
**Mucolytic (Inhaled):**
* Same as adult dosing: 3 mL to 5 mL of a 20% solution or 6 mL to 10 mL of a 10% solution administered via nebulizer every 4 to 12 hours.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustments are typically recommended for IV or oral use in acetaminophen overdose. For mucolytic use, dose adjustments are generally not required.
* **Hepatic Impairment:** No specific dose adjustments are typically recommended for IV or oral use in acetaminophen overdose.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Active gastrointestinal bleeding (for oral administration).
## Adverse Effects
* **Common (especially with IV):** Anaphylactoid reactions (rash, pruritus, angioedema, bronchospasm, dyspnea, hypotension), nausea, vomiting, diarrhea, fever.
* **Less Common:** Headache, dizziness, tinnitus, rhinorrhea.
* **Inhalation:** Bronchospasm, stomatitis, nausea, vomiting.
## Key Drug Interactions
* **Activated Charcoal:** May adsorb oral acetylcysteine, reducing its efficacy in acetaminophen overdose. Administer oral acetylcysteine at least 1 hour after activated charcoal.
* **Nitroglycerin:** May potentiate the vasodilatory effects of nitroglycerin, leading to hypotension and headache.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels and hepatic transaminases (AST, ALT) at baseline and every 24 hours until levels normalize or are undetectable and liver function tests are improving.
* Monitor for signs of anaphylactoid reaction (vital signs, respiratory status, skin).
* **Mucolytic Use:**
* Respiratory status, sputum volume and viscosity, and patient comfort.
* Monitor for bronchospasm.
## Clinical Pearls
* For IV acetylcysteine in acetaminophen overdose, a loading dose is critical for efficacy.
* The antidote effect is greatest when initiated within 8-10 hours of acetaminophen ingestion. However, treatment should be initiated regardless of time if acetaminophen levels are in the treatment nomogram range or if overdose is suspected.
* Oral acetylcysteine has a characteristic sulfur odor, which can be masked with juice or carbonated beverages.
* Bronchospasm can occur with inhaled acetylcysteine; consider co-administration with a bronchodilator.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information, institutional protocols, and consider individual patient factors before making any treatment decisions.
