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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucus, decreasing its viscosity. It is also an antidote for acetaminophen overdose.
## Primary Indications
* **Acetaminophen Overdose:** To prevent or reduce liver damage.
* **Mucolytic:** To thin mucus in conditions like cystic fibrosis, chronic obstructive pulmonary disease (COPD), and pneumonia.
## Adult Dosing
**Acetaminophen Overdose:**
* **Loading Dose:** 150 mg/kg intravenously (IV) over 1 hour.
* **Second Dose:** 50 mg/kg IV over 16 hours.
* **Subsequent Doses:** 100 mg/kg IV over 16 hours.
* **Oral (if IV unavailable or patient tolerating):**
* Loading dose: 140 mg/kg orally.
* Subsequent doses: 70 mg/kg orally every 4 hours for 17 doses.
* **Maximum Dose:** Specific maximums depend on the amount of acetaminophen ingested and patient weight. Consult established protocols.
**Mucolytic:**
* **Inhaled:** 3 mL to 5 mL of a 20% solution or 6 mL of a 10% solution via nebulizer every 2 to 6 hours.
* **Oral:** 200 mg twice daily to 1000 mg daily in divided doses.
## Pediatric Dosing
**Acetaminophen Overdose:** Dosing is based on weight.
* **Loading Dose:** 150 mg/kg IV over 1 hour.
* **Second Dose:** 50 mg/kg IV over 16 hours.
* **Subsequent Doses:** 100 mg/kg IV over 16 hours.
* **Oral (if IV unavailable or patient tolerating):**
* Loading dose: 140 mg/kg orally.
* Subsequent doses: 70 mg/kg orally every 4 hours for 17 doses.
* **Maximum Dose:** Specific maximums depend on the amount of acetaminophen ingested and patient weight. Consult established protocols.
**Mucolytic:**
* **Inhaled:** 1 mL to 3 mL of a 20% solution or 3 mL of a 10% solution via nebulizer every 2 to 6 hours.
## Dose Adjustments
No specific dose adjustments are generally required for hepatic or renal impairment, though caution is advised, especially with oral formulations due to potential gastrointestinal effects.
## Contraindications
* Known hypersensitivity to acetylcysteine.
## Adverse Effects
* **Inhaled:** Bronchospasm, nausea, vomiting, stomatitis, rhinorrhea.
* **Intravenous:** Anaphylactoid reactions (rash, pruritus, urticaria, bronchospasm, angioedema, dyspnea), flushing, tachycardia, hypotension.
* **Oral:** Nausea, vomiting, diarrhea, rash.
## Key Drug Interactions
* **Activated Charcoal:** May decrease the absorption of oral acetylcysteine.
* **Nitroglycerin:** May potentiate the vasodilatory effects of nitroglycerin, leading to hypotension and headache.
## Monitoring
* **Acetaminophen Overdose:** Liver function tests (AST, ALT, bilirubin, INR), acetaminophen levels, renal function, and glucose. Monitor for signs of anaphylactoid reaction.
* **Mucolytic:** Respiratory status, oxygen saturation, and signs of bronchospasm.
## Clinical Pearls
* For IV administration in acetaminophen overdose, ensure adequate hydration. Dilute the preparation as recommended by the manufacturer or institutional protocol.
* The characteristic sulfurous odor of acetylcysteine can be unpleasant.
* Bronchodilators should be administered prior to inhaled acetylcysteine in patients with reactive airway disease to minimize bronchospasm.
* The efficacy of acetylcysteine for acetaminophen overdose is time-dependent; earlier administration is associated with better outcomes.
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**Disclaimer:** This information is intended for healthcare professionals. Always verify current prescribing information and consult relevant clinical guidelines or local protocols before initiating treatment.
