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# Acetylcysteine ## Overview Acetylcysteine is a mucolytic agent that breaks down disulfide bonds in mucus, decreasing its viscosity. It is also an antidote for acetaminophen overdose by replenishing glutathione stores. ## Primary Indications * **Acetaminophen Overdose:** Treatment of acetaminophen poisoning. * **Mucolytic:** Adjunct to therapies in patients with abnormal viscid or mucopurulent secretions in acute bronchopulmonary disease (e.g., bronchitis, emphysema, cystic fibrosis, pneumonia). ## Adult Dosing **Acetaminophen Overdose:** * **Loading Dose:** 150 mg/kg IV infused over 1 hour. * **Second Dose:** 50 mg/kg IV infused over 1 hour. * **Subsequent Doses:** 100 mg/kg IV infused over 16 hours. * **Total Duration:** Typically 21 hours. * **Maximum Dose:** Based on body weight and acetaminophen concentration. **Mucolytic:** * **Inhalation:** 1-10 mL of a 20% solution or 2-20 mL of a 10% solution, nebulized every 2-6 hours. * **Oral (less common):** 200 mg two to three times daily. ## Pediatric Dosing **Acetaminophen Overdose:** * Dosing is the same as adults (150 mg/kg loading, 50 mg/kg second dose, 100 mg/kg over 16 hours). * Maximum doses are calculated based on weight. **Mucolytic:** * **Inhalation:** * Children < 6 years: 1-2 mL of a 20% solution or 2-4 mL of a 10% solution, nebulized every 2-6 hours. * Children ≥ 6 years: 1-10 mL of a 20% solution or 2-20 mL of a 10% solution, nebulized every 2-6 hours. ## Dose Adjustments No specific dose adjustments are generally recommended for hepatic or renal impairment, but caution is advised. ## Contraindications * Hypersensitivity to acetylcysteine or any component of the formulation. * Active hemorrhage (for IV formulation, caution advised). ## Adverse Effects * **IV Administration:** Anaphylactoid reactions (rash, urticaria, pruritus, angioedema, bronchospasm, dyspnea, wheezing), flushing, tachycardia, hypotension. Nausea and vomiting can occur. * **Inhalation:** Bronchospasm (especially in asthmatics), stomatitis, nausea, rhinorrhea. * **Oral:** Nausea, vomiting, diarrhea. ## Key Drug Interactions * **Activated Charcoal:** May decrease the absorption of oral acetylcysteine. * **Nitroglycerin:** Concurrent use may potentiate hypotensive effects and increase nitrate levels. ## Monitoring * **Acetaminophen Overdose:** Acetaminophen levels, liver function tests (ALT, AST, bilirubin, PT/INR), renal function, glucose. Monitor for anaphylactoid reactions during IV infusion. * **Mucolytic:** Respiratory status, patient's ability to clear secretions. Monitor for bronchospasm. ## Clinical Pearls * For IV acetylcysteine in acetaminophen overdose, consider initiating treatment even if the last acetaminophen dose was >24 hours prior if clinical suspicion of severe overdose or if levels are still elevated. * Dilute IV acetylcysteine for infusion to reduce the risk of anaphylactoid reactions. * Bronchodilators should be administered prior to nebulized acetylcysteine in patients with reactive airway disease. * The odor of acetylcysteine can be unpleasant; this is normal. *** *This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the current prescribing information and relevant clinical guidelines before making any treatment decisions.*