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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that decreases the viscosity of respiratory tract secretions. It also acts as an antidote for acetaminophen overdose by replenishing hepatic glutathione stores.
## Primary Indications
* **Acetaminophen Overdose:** Treatment of acetaminophen toxicity.
* **Mucolytic:** Adjunct therapy in patients with abnormal mucus secretions (e.g., chronic bronchitis, emphysema, tracheobronchitis, bronchiectasis, cystic fibrosis, atelectasis).
## Adult Dosing
**Acetaminophen Overdose (Oral/IV):**
* **Loading Dose:** 140 mg/kg orally or IV.
* **Maintenance Dose:** 70 mg/kg orally or IV every 4 hours for 17 doses.
* **Note:** IV dosing protocols may vary; some recommend a 3-bag infusion over 21 hours (e.g., 150 mg/kg over 60 min, followed by 12.5 mg/kg/hr for 4 hours, then 6.25 mg/kg/hr for 16 hours). Check institutional protocol.
**Mucolytic (Nebulization):**
* 3-10 mL of a 20% solution (600-2000 mg) or 6-12 mL of a 10% solution (600-1200 mg) every 3-4 hours as needed.
* **Note:** Nebulized acetylcysteine may be mixed with an equal volume of sterile water or normal saline. The concentration and frequency should be adjusted based on patient response and tolerance.
## Pediatric Dosing
**Acetaminophen Overdose (Oral/IV):**
* Dosing is the same as adult: 140 mg/kg orally or IV loading dose, followed by 70 mg/kg orally or IV every 4 hours for 17 doses.
* **Note:** Specific IV infusion protocols may be adjusted for pediatric patients. Check institutional protocol.
**Mucolytic (Nebulization):**
* Dosing is weight-based and depends on concentration.
* For 10% solution: 1 mL/kg (100 mg/kg) tid-qid.
* For 20% solution: 0.5 mL/kg (100 mg/kg) tid-qid.
* Maximum dose typically not to exceed 600 mg per dose.
## Dose Adjustments
No specific dose adjustments are typically required for hepatic or renal impairment, though caution is advised in severe cases due to potential accumulation.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Active gastrointestinal bleeding (for oral formulation).
## Adverse Effects
* **Common:** Nausea, vomiting, stomatitis, diarrhea, rash, urticaria, pruritus.
* **Less Common/Serious:** Bronchospasm (especially in asthmatics), anaphylactoid reactions, fever, dizziness.
* **IV Administration:** Anaphylactoid reactions, flushing, hypotension, tachycardia.
## Key Drug Interactions
* **Activated Charcoal:** May adsorb oral acetylcysteine, potentially reducing its efficacy. Administer acetylcysteine at least 1 hour after activated charcoal.
* **Nitroglycerin:** Potential for additive hypotensive effects and headache.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels.
* Liver function tests (LFTs).
* Prothrombin time (PT)/International Normalized Ratio (INR).
* Renal function.
* Electrolytes.
* **Mucolytic Use:**
* Respiratory status (lung sounds, oxygen saturation, work of breathing).
* Effectiveness in clearing secretions.
* Signs of bronchospasm.
## Clinical Pearls
* The characteristic sulfurous odor may cause nausea and vomiting; antiemetics may be considered.
* For IV administration, especially in acetaminophen overdose, monitor closely for anaphylactoid reactions.
* Nebulized acetylcysteine can sometimes cause bronchospasm; a bronchodilator may be co-administered, particularly in patients with reactive airway disease.
* Oral acetylcysteine for acetaminophen overdose is most effective when initiated within 8-10 hours of ingestion.
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*This information is intended for healthcare professionals. Always verify current prescribing information and institutional protocols before initiating treatment.*
