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# Acetylcysteine ## Overview Acetylcysteine (NAC) is a mucolytic agent that disrupts disulfide bonds in mucoproteins, decreasing the viscosity of mucus. It is also an antidote for acetaminophen overdose. ## Primary Indications * **Acetaminophen Overdose:** Antidote to prevent or reduce liver toxicity. * **Mucolytic Agent:** To help thin mucus in conditions such as COPD, cystic fibrosis, and pneumonia. ## Adult Dosing * **Acetaminophen Overdose:** * **Initial Dose:** 150 mg/kg IV infused over 1 hour. * **Second Dose:** 50 mg/kg IV infused over 4 hours. * **Third Dose:** 100 mg/kg IV infused over 16 hours. * **Total Duration:** 21 hours. * **Oral Dosing:** 140 mg/kg PO loading dose, followed by 70 mg/kg PO every 4 hours for 17 doses. * **Note:** Doses may need to be adjusted based on acetaminophen levels and time from ingestion. Consult specific protocols. * **Mucolytic Agent:** * **Inhalation:** 3 mL of 20% solution or 6 mL of 10% solution via nebulizer every 3-4 hours as needed. * **Direct Instillation:** 1-2 mL of 10-20% solution into tracheostomy tube every 1-4 hours. ## Pediatric Dosing * **Acetaminophen Overdose:** Dosing is the same as adult dosing (150 mg/kg IV, then 50 mg/kg IV, then 100 mg/kg IV). Oral dosing is also the same. * **Mucolytic Agent:** * **Inhalation:** * 10% solution: 1-2 mL every 2-6 hours. * 20% solution: 1 mL every 2-6 hours. * **Note:** Pediatric dosing for mucolytic use may vary by institution. ## Dose Adjustments * **Renal or Hepatic Impairment:** No specific dose adjustments are typically required for acetaminophen overdose. For mucolytic use, caution may be advised, but no specific adjustments are generally established. ## Contraindications * Known hypersensitivity to acetylcysteine. * **Intravenous formulation:** Caution in patients with asthma due to potential for bronchospasm. ## Adverse Effects * **Intravenous:** Anaphylactoid reactions (rash, pruritus, urticaria, bronchospasm, dyspnea, angioedema), flushing, tachycardia, hypotension. Nausea and vomiting are common. * **Inhalation:** Bronchospasm, rhinorrhea, nausea, vomiting, stomatitis. ## Key Drug Interactions * **Activated Charcoal:** May adsorb acetylcysteine given orally for acetaminophen overdose, potentially reducing its efficacy. If both are administered, separate by at least 1 hour. ## Monitoring * **Acetaminophen Overdose:** * Acetaminophen serum levels. * Liver function tests (ALT, AST, bilirubin, INR). * Renal function and electrolytes. * Clinical signs of hepatotoxicity. * **Mucolytic Agent:** * Respiratory status and sputum production. * Signs of bronchospasm. ## Clinical Pearls * The smell of acetylcysteine is sulfurous and unpleasant; this may cause nausea or vomiting, especially with oral administration. * For IV administration in acetaminophen overdose, a continuous infusion is generally preferred to minimize risk of anaphylactoid reactions. * If bronchospasm occurs with inhaled acetylcysteine, it can often be managed with bronchodilators. *** *This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols before administering any medication.*