Acetyl%25252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520cysteine

# Acetylcysteine ## Overview Acetylcysteine (N-acetylcysteine, NAC) is a mucolytic agent and an antidote for acetaminophen overdose. It acts by replenishing glutathione stores and directly binding to toxic metabolites of acetaminophen. ## Primary Indications * **Acetaminophen overdose:** To prevent or reduce liver toxicity. * **Mucolytic:** To thin and loosen mucus in respiratory conditions such as chronic bronchitis, emphysema, and cystic fibrosis. ## Adult Dosing **Acetaminophen Overdose:** * **Loading Dose:** 150 mg/kg IV over 1 hour. * **Second Dose:** 50 mg/kg IV over 1 hour, 4 hours after the loading dose. * **Maintenance Doses:** 100 mg/kg IV over 16 hours (total infusion time of 17 hours), following the second dose. * Maximum infusion rate for maintenance doses is typically 6.25 mg/kg/hr. * The total dose and duration may be adjusted based on acetaminophen levels, clinical response, and hepatic function. * Oral dosing is an alternative but may be associated with higher rates of emesis. **Mucolytic:** * **Nebulization:** 1-10 mL of a 20% solution (200-1000 mg) or 2-5 mL of a 10% solution (200-500 mg) every 2-6 hours as needed. * **Oral (less common for mucolytic):** Typically 200 mg two to three times daily. ## Pediatric Dosing **Acetaminophen Overdose:** * Dosing is weight-based and follows the same regimen as adults: * **Loading Dose:** 150 mg/kg IV over 1 hour. * **Second Dose:** 50 mg/kg IV over 1 hour, 4 hours after the loading dose. * **Maintenance Doses:** 100 mg/kg IV over 16 hours. * Consider higher concentrations for IV infusions in neonates and infants to avoid fluid overload. **Mucolytic:** * **Nebulization:** 1-10 mL of a 20% solution (200-1000 mg) or 2-5 mL of a 10% solution (200-500 mg) every 2-6 hours as needed. ## Dose Adjustments * **Renal Impairment:** No specific dose adjustment is routinely recommended for mild to moderate renal impairment. Use with caution in severe renal impairment. * **Hepatic Impairment:** Acetaminophen overdose treatment should continue even in patients with hepatic impairment, as liver injury is the primary concern. Dose adjustments are not typically made for the antidote itself. ## Contraindications * Known hypersensitivity to acetylcysteine. * Consider caution in patients with bronchospasm or severe asthma, especially with nebulized formulations. ## Adverse Effects **IV Administration (most common with overdose treatment):** * Anaphylactoid reactions (ranging from rash and pruritus to bronchospasm and angioedema). * Nausea, vomiting. * Tachycardia, hypotension. * Flushing. * Rarely, seizures. **Nebulized Administration:** * Bronchospasm, particularly in patients with reactive airway disease. * Nausea, vomiting. * Stomatitis. * Rhinorrhea. ## Key Drug Interactions * **Activated Charcoal:** May bind to oral acetylcysteine and reduce its absorption. If both are administered orally, separate administration by at least 1 hour. * **Nitroglycerin:** May potentiate the vasodilatory effects of nitroglycerin, leading to increased risk of hypotension. ## Monitoring * **Acetaminophen Overdose:** * Serum acetaminophen levels (timed from ingestion). * Liver function tests (AST, ALT, bilirubin, INR, albumin) – baseline and then periodically. * Renal function (BUN, creatinine). * Electrolytes. * Glucose. * Clinical signs of liver toxicity. * Vital signs, especially during IV infusion. * **Mucolytic:** * Pulmonary status, respiratory rate, oxygen saturation. * Patient's subjective response to treatment. * Potential for bronchospasm. ## Clinical Pearls * The IV formulation for acetaminophen overdose is a life-saving antidote. Prompt administration is crucial, especially if acetaminophen levels are in the toxic range or if the time of ingestion is unknown. * Anaphylactoid reactions are common with IV acetylcysteine but are usually mild and can be managed by slowing the infusion rate or administering antihistamines. Severe reactions are rare. * For nebulized acetylcysteine, consider co-administration with a bronchodilator (e.g., albuterol) to mitigate the risk of bronchospasm. * Ensure adequate hydration, especially when using nebulized acetylcysteine, to help thin secretions. *** **Disclaimer:** This information is intended for healthcare professionals and is not a substitute for clinical judgment. Always consult the most current prescribing information and institutional protocols for complete details.