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# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucoproteins, reducing mucus viscosity. It is also an antidote for acetaminophen overdose by replenishing glutathione stores. ## Primary Indications * **Acetaminophen Overdose:** Treatment is most effective when initiated within 8 hours of ingestion. * **Mucolytic Agent:** For conditions with thickened or abnormal mucus secretions (e.g., chronic bronchitis, COPD, cystic fibrosis). ## Adult Dosing **Acetaminophen Overdose:** * **Intravenous (IV):** Typically a 3-bag (or 4-bag) regimen is used. * **Loading Dose:** 150 mg/kg IV over 1 hour. * **Second Infusion:** 50 mg/kg IV over 1 hour. * **Third Infusion:** 100 mg/kg IV over 16 hours. * **Maximum Dose:** Specific maximums vary based on protocol and duration, but generally, total dose should not exceed 300 mg/kg over 24 hours. * **Oral (PO):** Less common due to palatability and potential for vomiting. * **Loading Dose:** 140 mg/kg PO. * **Subsequent Doses:** 70 mg/kg PO every 4 hours for 17 doses. * **Maximum Dose:** 1400 mg per dose. **Mucolytic Agent:** * **Nebulized:** 3 mL of 20% solution (600 mg) or 6 mL of 10% solution (600 mg) nebulized every 4-12 hours. * **Oral:** 600 mg twice daily. * **Intravenous (IV):** Used for mucolytic purposes only in select situations (e.g., severe respiratory distress unresponsive to other treatments), with dosing typically ranging from 200-400 mg every 4-6 hours. This route is less common for mucolytic effect. ## Pediatric Dosing **Acetaminophen Overdose:** * **Intravenous (IV):** Same regimen as adults (150 mg/kg over 1 hour, then 50 mg/kg over 1 hour, then 100 mg/kg over 16 hours). Maximum dose considerations apply. * **Oral (PO):** Same regimen as adults (140 mg/kg PO loading dose, then 70 mg/kg PO every 4 hours for 17 doses). Maximum dose considerations apply. **Mucolytic Agent:** * **Nebulized:** 10% solution is preferred. * **Infants and Young Children:** 1 mL of 10% solution (100 mg) nebulized every 2-6 hours. * **Older Children:** 3 mL of 10% solution (300 mg) nebulized every 2-6 hours. * Dosing may be adjusted based on protocol. ## Dose Adjustments * **Hepatic Impairment:** No specific dose adjustment recommended for acetaminophen overdose treatment, as the goal is to replenish glutathione. For mucolytic use, caution may be warranted due to potential for reduced drug metabolism, though data is limited. * **Renal Impairment:** No specific dose adjustment recommended for acetaminophen overdose treatment. For mucolytic use, caution may be warranted, though data is limited. ## Contraindications * Hypersensitivity to acetylcysteine or any component of the formulation. * Certain formulations may contain sulfite preservatives, posing a risk for patients with sulfite sensitivity. ## Adverse Effects * **Nebulized:** Bronchospasm, bronchoconstriction, rhinorrhea, nausea, vomiting, stomatitis. * **Intravenous (IV):** Anaphylactoid reactions (rash, urticaria, pruritus, angioedema, bronchospasm, dyspnea), hypotension, tachycardia. Rare cases of flushing, fever, headache. * **Oral:** Nausea, vomiting, diarrhea, stomatitis. ## Key Drug Interactions * **Activated Charcoal:** May adsorb oral acetylcysteine, reducing its absorption. Separate administration by at least 1 hour. * **Nitroglycerin:** Concurrent use may cause additive hypotension and headache. ## Monitoring * **Acetaminophen Overdose:** * Serum acetaminophen levels (to assess toxicity and guide treatment duration). * Liver function tests (LFTs), coagulation profile, creatinine, glucose, electrolytes (especially in severe overdose or prolonged treatment). * Clinical status (mental status, vital signs, urine output). * **Mucolytic Use:** * Respiratory status (e.g., lung sounds, work of breathing, oxygen saturation). * Bronchospasm. ## Clinical Pearls * For IV acetylcysteine in acetaminophen overdose, prompt administration is critical for efficacy. * Anaphylactoid reactions to IV acetylcysteine are common but usually manageable and do not necessarily warrant discontinuation. Pretreatment with an antihistamine may be considered. * Oral acetylcysteine should be diluted and administered via nasogastric tube if vomiting is severe. * Nebulized acetylcysteine can sometimes induce bronchospasm; coadministration with a bronchodilator (e.g., albuterol) is often recommended, especially in patients with reactive airway disease. *** **Disclaimer:** This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant guidelines before making any treatment decisions.