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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:** To prevent or reduce liver damage.
* **Mucolytic:** To thin mucus in patients with conditions such as cystic fibrosis, chronic obstructive pulmonary disease (COPD), and pneumonia.
## Adult Dosing
* **Acetaminophen Overdose:**
* **Oral Loading Dose:** 140 mg/kg as a single dose.
* **Subsequent Oral Doses:** 70 mg/kg every 4 hours for 17 doses.
* **Intravenous (IV) Loading Dose:** 150 mg/kg over 1 hour.
* **IV Subsequent Doses:** 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours.
* *Note: IV dosing protocols may vary; consult local protocols.*
* **Mucolytic:**
* **Nebulized:** 10% solution: 3-5 mL every 3-4 hours, or 20% solution: 2-5 mL every 3-4 hours.
* **Direct Instillation:** 10-20% solution into tracheostomy tube, 1-10 mL every 1-4 hours.
* **Oral:** 200 mg twice daily or three times daily for chronic bronchitis or COPD. *Note: Oral use for mucolytic indications is less common and may vary by region.*
## Pediatric Dosing
* **Acetaminophen Overdose:**
* **Oral Loading Dose:** 140 mg/kg as a single dose.
* **Subsequent Oral Doses:** 70 mg/kg every 4 hours for 17 doses.
* **Intravenous (IV) Loading Dose:** 150 mg/kg over 1 hour.
* **IV Subsequent Doses:** 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours.
* *Note: IV dosing protocols may vary; consult local protocols.*
* **Mucolytic:**
* **Nebulized:** 10% solution: 1-3 mL every 3-4 hours, or 20% solution: 1-2 mL every 3-4 hours.
* **Oral:** 200 mg twice daily for children > 14 years. Dosing for younger children is less established and may vary by local protocol.
## Dose Adjustments
No specific dose adjustments are typically required for hepatic or renal impairment, though caution is advised.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Active hemorrhage (for IV use in acetaminophen overdose, though benefits generally outweigh risks if overdose is confirmed).
## Adverse Effects
* **Nebulized:** Bronchospasm, stomatitis, nausea, vomiting, rhinorrhea.
* **Oral:** Nausea, vomiting, diarrhea, abdominal pain.
* **IV:** Anaphylactoid reactions (rash, urticaria, angioedema, bronchospasm, dyspnea, hypotension), fever, chills. Rapid infusion may increase the risk of anaphylactoid reactions.
## Key Drug Interactions
* **Activated Charcoal:** May bind to oral acetylcysteine, reducing its absorption. 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, liver function tests (ALT, AST, bilirubin, INR), glucose, electrolytes, and renal function. Monitor for signs of anaphylactoid reaction.
* **Mucolytic:** Respiratory status, sputum volume and viscosity, and signs of bronchospasm.
## Clinical Pearls
* The characteristic sulfurous odor of acetylcysteine can be unpleasant and may cause nausea. Diluting it or administering it with a flavored agent can improve palatability for oral or nebulized administration.
* For IV administration in acetaminophen overdose, a continuous infusion is generally preferred over bolus dosing to reduce the risk of anaphylactoid reactions.
* Patients receiving nebulized acetylcysteine may require co-administration of a bronchodilator to prevent or manage bronchospasm.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information or local protocols for definitive guidance.*
