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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that works by breaking disulfide bonds in mucus, making it thinner and easier to expectorate. It is also an antidote for acetaminophen overdose.
## Primary Indications
* Acetaminophen overdose
* Adjunct in management of bronchitis, emphysema, and other COPD exacerbations with excessive, tenacious mucus.
* Adjunct in patients with cystic fibrosis or atelectasis.
* Prophylaxis for contrast-induced nephropathy (CIN) in patients undergoing procedures with contrast dye.
## Adult Dosing
**Acetaminophen Overdose:**
* **Oral Loading Dose:** 140 mg/kg
* **Oral Maintenance Dose:** 70 mg/kg every 4 hours for 17 doses.
* **IV Loading Dose:** 150 mg/kg over 1 hour.
* **IV Maintenance Dose 1:** 50 mg/kg over 4 hours.
* **IV Maintenance Dose 2:** 100 mg/kg over 16 hours.
* *Note: IV dosing is preferred due to better absorption and reduced risk of vomiting. Specific protocols may vary.*
**Mucolytic:**
* **Nebulized:** 10% solution: 3-5 mL every 4-12 hours. 20% solution: 1-2 mL every 4-12 hours.
* **Direct Instillation (Tracheostomy):** 1-2 mL of 10% or 20% solution every 1-4 hours.
**Contrast-Induced Nephropathy (CIN) Prophylaxis:**
* **Oral:** 600 mg twice daily for 2 days (1 day before and 1 day after contrast administration).
## Pediatric Dosing
**Acetaminophen Overdose:**
* Dosing is the same as adult dosing (140 mg/kg PO loading, 70 mg/kg PO maintenance q4h x 17 doses; or 150 mg/kg IV over 1 hour, 50 mg/kg IV over 4 hours, 100 mg/kg IV over 16 hours).
**Mucolytic:**
* **Nebulized:**
* **10% solution:** 1-3 mL every 4-12 hours.
* **20% solution:** 1 mL every 4-12 hours.
* *Note: Concentration and volume may depend on patient tolerance and local protocol.*
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustments are routinely recommended for the mucolytic indication. For IV acetaminophen overdose, caution and close monitoring are advised, though specific adjustments are not well-defined.
* **Hepatic Impairment:** No specific dose adjustments are routinely recommended for the mucolytic indication. For IV acetaminophen overdose, caution and close monitoring are advised, though specific adjustments are not well-defined.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
## Adverse Effects
* **Nebulized:** Bronchospasm, nausea, vomiting, stomatitis, rhinorrhea, urticaria, rash.
* **IV:** Anaphylactoid reactions (hypotension, bronchospasm, angioedema, urticaria), fever, rash.
* **Oral:** Nausea, vomiting, diarrhea.
## Key Drug Interactions
* **Activated Charcoal:** May adsorb oral acetylcysteine, reducing its efficacy in acetaminophen overdose. Administer acetylcysteine at least 1 hour after activated charcoal.
* **Nitroglycerin:** Concurrent use may potentiate the hypotensive effect of nitroglycerin.
## Monitoring
* **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests (LFTs), prothrombin time (PT), international normalized ratio (INR), renal function.
* **Mucolytic:** Pulmonary status, sputum volume and viscosity, patient's ability to expectorate, signs of bronchospasm.
* **CIN Prophylaxis:** Renal function (serum creatinine, BUN).
## Clinical Pearls
* The odor of acetylcysteine is distinct and unpleasant (sulfur-like); this is normal.
* For nebulized acetylcysteine, concomitant administration of a bronchodilator may be necessary to mitigate bronchospasm.
* In acetaminophen overdose, initiating treatment within 8-10 hours of ingestion is associated with the best outcomes.
* IV acetylcysteine for acetaminophen overdose can cause rash and pruritus. These can often be managed with antihistamines. Severe anaphylactoid reactions require immediate discontinuation and management of symptoms.
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*This information is intended for healthcare professionals. Always consult the official prescribing information and institutional protocols for the most current and complete drug details before prescribing.*
