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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent used to thin mucus secretions and as an antidote for acetaminophen overdose. It is available in oral and intravenous formulations.
## Primary Indications
* **Acetaminophen Overdose:** Antidote to prevent liver damage.
* **Mucolytic:** To reduce the viscosity of respiratory tract secretions in patients with conditions such as chronic bronchitis, emphysema, cystic fibrosis, and tracheostomy.
## Adult Dosing
**Acetaminophen Overdose:**
* **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 the next 16 hours (if needed, based on acetaminophen levels and clinical status).
* *Note:* Alternative oral dosing protocols exist and may be preferred based on local guidelines; consult specific protocols for oral loading and maintenance doses.
**Mucolytic:**
* **Inhaled:** 3 mL to 5 mL of a 20% solution or 6 mL to 10 mL of a 10% solution via nebulizer every 3 to 4 hours.
* **Oral:** 200 mg twice daily or 200 mg three times daily.
## Pediatric Dosing
**Acetaminophen Overdose:**
* **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 the next 16 hours (if needed).
* *Note:* Oral dosing protocols are also available for pediatric patients and should be followed per local guidelines.
**Mucolytic:**
* **Inhaled:** 1 mL to 2 mL of a 20% solution or 2 mL to 5 mL of a 10% solution via nebulizer every 3 to 4 hours.
* **Oral:** 50 mg/kg twice daily or 50 mg/kg three times daily. Maximum dose typically 200 mg three times daily.
## Dose Adjustments
No specific dose adjustments are routinely recommended for hepatic or renal impairment for mucolytic use. For acetaminophen overdose, dosing is weight-based and not typically adjusted for organ dysfunction, but closer monitoring is warranted.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Active bronchospasm (for inhaled formulations).
## Adverse Effects
* **Common (Oral/Inhaled):** Nausea, vomiting, stomatitis, rhinorrhea, drowsiness.
* **Less Common (Oral/Inhaled):** Bronchospasm, urticaria, pruritus.
* **IV Acetaminophen Antidote:** Anaphylactoid reactions (rash, pruritus, bronchospasm, angioedema, hypotension) can occur, often during the initial infusion. Bronchospasm is a significant concern.
## Key Drug Interactions
* **Activated Charcoal:** May reduce the absorption of oral acetylcysteine. If given for acetaminophen overdose, it should be administered at least 1 hour before or after oral acetylcysteine.
* **Nitroglycerin:** Concomitant use may potentiate hypotension and headache.
## Monitoring
* **Acetaminophen Overdose:** Serial acetaminophen and ALT levels, liver function tests, prothrombin time, glucose, electrolytes, and renal function. Clinical signs of hepatotoxicity.
* **Mucolytic Use:** Respiratory status, sputum thickness and ease of expectoration. Monitor for bronchospasm.
## Clinical Pearls
* The effectiveness of acetylcysteine for acetaminophen overdose is time-dependent; treatment should be initiated as soon as possible after ingestion.
* For IV administration in acetaminophen overdose, patients should be monitored closely for anaphylactoid reactions, particularly during the first hour of infusion. Pretreatment with an H1 and H2 blocker may be considered.
* Dilute inhaled acetylcysteine to avoid airway irritation.
* Oral acetylcysteine has a characteristic sulfurous odor, which may lead to poor compliance.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and local protocols before administering any medication.*
