Acetyl%252525252525252525252525252525252525252525252525252525252525252525252525252520cysteine

# Acetylcysteine ## Overview N-acetylcysteine (NAC) is an mucolytic agent that can also act as an antidote for acetaminophen overdose. It is thought to replenish glutathione stores and directly conjugate with the toxic metabolite NAPQI. ## Primary Indications * **Acetaminophen overdose:** Used as an antidote. * **Mucolytic:** To thin bronchial secretions in patients with cystic fibrosis, chronic bronchitis, or other pulmonary diseases with excess mucus. ## Adult Dosing **Acetaminophen Overdose:** * **Intravenous (IV):** Typically a 2-bag regimen. * **Loading dose:** 150 mg/kg IV infused over 60 minutes. * **First maintenance dose:** 50 mg/kg IV infused over 60 minutes, followed by * **Subsequent maintenance doses:** 100 mg/kg IV infused over 16 hours (total treatment duration of 21 hours). * Dosing is often weight-based and concentration-dependent. Consult local protocol for specific mg/kg/hr rates and bag sizes. Maximum total dose may vary by protocol. * **Oral (PO):** Less preferred due to gastrointestinal intolerance but may be used if IV access is not feasible. * **Loading dose:** 140 mg/kg PO. * **Subsequent doses:** 70 mg/kg PO every 4 hours for 17 doses (total 72 hours). * Activated charcoal may be given prior to NAC if ingestion is recent. Antiemetics are often administered concurrently. **Mucolytic:** * **Inhaled (nebulized):** 1 to 10 mL of 20% solution or 2 to 10 mL of 10% solution every 2 to 6 hours. May be diluted further with sterile water or saline. * **Oral (PO):** 200 mg to 600 mg twice daily. ## Pediatric Dosing **Acetaminophen Overdose:** * **Intravenous (IV):** Same as adult dosing (150 mg/kg loading dose, followed by 50 mg/kg and 100 mg/kg maintenance doses). Careful calculation is crucial due to smaller patient size. Maximum doses may be lower. Consult local protocol. * **Oral (PO):** Same as adult dosing (140 mg/kg loading dose, followed by 70 mg/kg every 4 hours for 17 doses). **Mucolytic:** * **Inhaled (nebulized):** 1 to 10 mL of 20% solution or 2 to 10 mL of 10% solution every 2 to 6 hours. May be diluted further with sterile water or saline. ## Dose Adjustments * **Renal impairment:** No specific dose adjustments are typically recommended, but caution is advised. * **Hepatic impairment:** No specific dose adjustments are typically recommended for acetaminophen overdose, as liver function impacts acetaminophen metabolism, not NAC's direct antidote effect, though severe hepatic dysfunction may prolong elimination. ## Contraindications * Known hypersensitivity to acetylcysteine. ## Adverse Effects * **Anaphylactoid reactions:** Bronchospasm, angioedema, urticaria, rash, pruritus, and hypotension are common with IV administration, particularly during the loading dose. Antihistamines and corticosteroids may be given prophylactically. * **Gastrointestinal:** Nausea, vomiting, diarrhea. Oral NAC is particularly associated with emesis. * **Respiratory:** Bronchospasm (inhaled route), rhinorrhea. * **Other:** Fever, headache. ## Key Drug Interactions * **Activated Charcoal:** May decrease the absorption of oral acetylcysteine. Administer NAC at least 1 hour after charcoal. * **Nitroglycerin:** May potentiate the vasodilatory effects of nitroglycerin. ## Monitoring * **Acetaminophen Overdose:** * Serum acetaminophen levels. * Liver function tests (AST, ALT, bilirubin, INR). * Renal function. * Clinical status: alertness, vital signs, signs of anaphylaxis. * Prothrombin time (PT) and activated partial thromboplastin time (aPTT) may be monitored in severe cases. * **Mucolytic:** * Respiratory status, sputum production and consistency. * Pulmonary function tests. ## Clinical Pearls * Rapid IV infusion of acetylcysteine can cause anaphylactoid reactions. Slowing the infusion rate can often mitigate these reactions. * Oral acetylcysteine is less palatable and frequently causes vomiting. Antiemetics are often required. * The efficacy of acetylcysteine for acetaminophen overdose is time-dependent; it is most effective when initiated within 8-10 hours of ingestion. However, it should still be administered even if presentation is delayed, especially if acetaminophen levels are supratherapeutic or if the time of ingestion is unknown. * A non-toxic metabolite (glucuronide conjugate) is formed, which is cleared renally. --- *This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always verify current prescribing information with the manufacturer's product information or other reliable sources before making clinical decisions.*