Acetyl%252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520cysteine

## Acetylcysteine ### Overview Acetylcysteine (NAC) is a mucolytic agent and an antidote for acetaminophen overdose. It works by breaking disulfide bonds in mucoproteins, reducing mucus viscosity, and by replenishing glutathione stores. ### Primary Indications * **Acetaminophen Overdose:** To prevent or reduce liver toxicity. * **Mucolytic:** To thin and loosen mucus in respiratory conditions such as cystic fibrosis, chronic obstructive pulmonary disease (COPD), and bronchitis. ### Adult Dosing **Acetaminophen Overdose:** * **Loading Dose:** 150 mg/kg IV infused over 1 hour. * **Second Dose:** 50 mg/kg IV infused over 16 hours. * **Subsequent Doses:** Some protocols use a continuous infusion of 6.25 mg/kg/hr for up to 72 hours, especially if acetaminophen levels remain elevated or liver enzymes are rising. * **Oral Protocol:** 140 mg/kg orally as a loading dose, followed by 70 mg/kg orally every 4 hours for 17 doses. **Mucolytic:** * **Inhaled:** 3 mL to 5 mL of a 20% solution or 6 mL to 10 mL of a 10% solution via nebulization every 2 to 6 hours. * **Oral (unlabeled use, for acetaminophen overdose adjunct):** Doses vary, often 200 mg/kg/day divided every 4-6 hours. ### Pediatric Dosing **Acetaminophen Overdose:** * Dosing is weight-based and the same as adult dosing (150 mg/kg IV loading, 50 mg/kg IV maintenance). **Mucolytic:** * **Inhaled:** 1 mL to 2 mL of a 20% solution or 2 mL to 5 mL of a 10% solution via nebulization every 2 to 6 hours. ### Dose Adjustments * **Renal/Hepatic Impairment:** No dose adjustment is typically necessary for renal or hepatic impairment in the setting of acetaminophen overdose, as the risk of toxicity outweighs potential accumulation issues. For mucolytic use, caution may be warranted, but specific adjustments are not well-defined. ### Contraindications * Hypersensitivity to acetylcysteine. * Acute bronchospasm (for inhaled formulations, though caution is advised rather than strict contraindication). ### Adverse Effects * **IV:** Anaphylactoid reactions (rash, pruritus, angioedema, bronchospasm, hypotension), flushing, dyspnea, fever. * **Inhaled:** Bronchospasm, nausea, vomiting, stomatitis, rhinorrhea. * **Oral:** Nausea, vomiting, diarrhea. ### Key Drug Interactions * **Activated Charcoal:** Can adsorb oral acetylcysteine, reducing its absorption. Separate administration by at least 1 hour. * **Nitroglycerin:** Increased hypotensive effect. Monitor blood pressure. ### Monitoring * **Acetaminophen Overdose:** Serum acetaminophen levels, liver function tests (AST, ALT, bilirubin, INR), prothrombin time, glucose, electrolytes, and renal function. Clinical signs of liver injury. * **Mucolytic:** Respiratory status, sputum volume and viscosity, and signs of bronchospasm. ### Clinical Pearls * IV acetylcysteine for acetaminophen overdose should be initiated as soon as overdose is suspected, regardless of serum acetaminophen levels, and continued even if levels are not available. * Anaphylactoid reactions are common with IV acetylcysteine and can often be managed by slowing the infusion rate and administering antihistamines. * For inhaled acetylcysteine, co-administration with a bronchodilator may be beneficial to prevent or treat bronchospasm. *** *Please verify current prescribing information and institutional protocols before administering this medication.*