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# Acetylcysteine
## Overview
Acetylcysteine (NAC) is a mucolytic agent used to break down thick mucus in the airways and is also an antidote for acetaminophen overdose.
## Primary Indications
* **Acetaminophen overdose:** To prevent or reduce liver toxicity.
* **Mucolytic:** To thin mucus in patients with chronic bronchitis, cystic fibrosis, and other respiratory conditions associated with excessive mucus production.
## Adult Dosing
**Acetaminophen Overdose:**
* **Loading Dose:** 150 mg/kg IV infused over 1 hour.
* **Second Dose:** 50 mg/kg IV infused over 1 hour, 4 hours after the loading dose.
* **Subsequent Doses:** 100 mg/kg IV infused over 16 hours, starting 8 hours after the second dose.
* *Maximum total dose is not typically capped but depends on acetaminophen ingestion amount. Protocols may vary.*
* **Oral Protocol:** 140 mg/kg PO loading dose, followed by 70 mg/kg PO every 4 hours for 17 doses.
**Mucolytic:**
* **Inhaled:** 10% solution, 3-5 mL nebulized every 3-4 hours, or 20% solution, 3-5 mL nebulized every 6-8 hours.
* **Oral:** 600 mg once daily or divided into two doses.
## Pediatric Dosing
**Acetaminophen Overdose:**
* **Loading Dose:** 150 mg/kg IV infused over 1 hour.
* **Second Dose:** 50 mg/kg IV infused over 1 hour, 4 hours after the loading dose.
* **Subsequent Doses:** 100 mg/kg IV infused over 16 hours, starting 8 hours after the second dose.
* *Maximum total dose is not typically capped but depends on acetaminophen ingestion amount. Protocols may vary.*
* **Oral Protocol:** 140 mg/kg PO loading dose, followed by 70 mg/kg PO every 4 hours for 17 doses.
**Mucolytic:**
* **Inhaled:**
* < 6 years: 10% solution, 1-2 mL nebulized every 3-4 hours.
* ≥ 6 years: 10% solution, 3-5 mL nebulized every 3-4 hours, or 20% solution, 3-5 mL nebulized every 6-8 hours.
* **Oral:** 600 mg once daily or divided into two doses.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment recommended, but caution advised.
* **Hepatic Impairment:** No specific dose adjustment recommended for mucolytic use; closely monitor liver function in overdose patients.
## Contraindications
* Hypersensitivity to acetylcysteine or its components.
## Adverse Effects
* **Common:** Nausea, vomiting, stomatitis (oral), rash, pruritus.
* **IV Administration:** Bronchospasm, anaphylactoid reactions (especially with rapid infusion), flushing, hypotension.
* **Inhaled:** Bronchospasm, rhinorrhea, nausea.
## Key Drug Interactions
* **Activated Charcoal:** May decrease absorption of oral acetylcysteine in overdose situations if given concurrently. Separate administration or use IV acetylcysteine.
* **Nitroglycerin:** Potentiation of vasodilatory effects may occur.
## Monitoring
* **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests (ALT, AST, bilirubin, PT/INR), renal function, glucose.
* **Mucolytic:** Respiratory status, sputum production, and thickness.
## Clinical Pearls
* For IV acetylcysteine in acetaminophen overdose, ensure adequate hydration and monitor for anaphylactoid reactions. Dilute for IV infusion to reduce risk of adverse reactions.
* Oral acetylcysteine may have an unpleasant sulfurous odor. Administer with flavored beverages to improve palatability.
* Bronchospasm can occur with inhaled acetylcysteine; consider co-administration with a bronchodilator.
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**Disclaimer:** This information is intended for clinical decision-making and does not replace comprehensive drug information resources. Always verify current prescribing information and institutional protocols before administering medications.
