What is acetylcysteine (N-acetylcysteine) infusion used for?

Primary Uses of Acetylcysteine Infusion in Clinical Practice

Acetylcysteine infusion is primarily indicated as an antidote for acetaminophen overdose to prevent or reduce hepatic injury, and as a mucolytic agent for patients with abnormal, viscid mucous secretions in various respiratory conditions. 1

Acetaminophen Overdose Management

Acetylcysteine is the definitive treatment for acetaminophen-induced hepatotoxicity:

• Initiation timing: Treatment should be started as soon as possible after overdose, and within 24 hours of ingestion 1
• Administration: Should be initiated without waiting for serum acetaminophen level results 2
• Efficacy: Significantly reduces hepatotoxicity (18% vs 58%) and mortality (0.7% vs 6%) compared to placebo 2
• Clinical benefits: Reduces development of cerebral edema (40% vs 68%) and need for vasopressors (48% vs 80%) 2

Risk Assessment

• For known time of ingestion: Use Rumack-Matthew nomogram to stratify risk 2
• For unknown time or extended-release preparations: Cannot use nomogram for risk stratification 2

Non-Acetaminophen Liver Failure

Acetylcysteine may benefit patients with acute liver failure not related to acetaminophen:

• Evidence: Meta-analyses show improvements in liver transplant-free survival (64% vs 26%) and overall survival (76% vs 59%) 2
• Recommendation: Grade 2+ recommendation to initiate acetylcysteine therapy in acute liver failure regardless of etiology 2
• Best candidates: Patients with grade I-II hepatic encephalopathy show greatest benefit 2

Respiratory Conditions

Acetylcysteine is indicated as adjuvant therapy for patients with abnormal or viscid mucous secretions in:

• Chronic bronchopulmonary diseases (emphysema, chronic bronchitis) 1
• Acute bronchopulmonary diseases (pneumonia, bronchitis) 1
• Pulmonary complications of cystic fibrosis 1
• Tracheostomy care 1
• Pulmonary complications associated with surgery 1
• Atelectasis due to mucous obstruction 1

COPD Management

• The European Respiratory Society/American Thoracic Society conditionally recommends mucolytic therapy (including N-acetylcysteine) for COPD patients with moderate to severe airflow obstruction and exacerbations despite optimal inhaled therapy 2
• Most effective dose: 600 mg twice daily 3

Pharmacokinetics

• Absorption: After oral doses of 200-400 mg, peak plasma concentration of 0.35-4 mg/L is achieved within 1-2 hours 4
• Distribution: Volume of distribution ranges from 0.33-0.47 L/kg with approximately 50% protein binding 4
• Elimination: Terminal half-life of 6.25 hours following oral administration 4
• Clearance: Renal clearance is 0.190-0.211 L/h/kg, with approximately 70% of clearance being non-renal 4

Adverse Effects

Common side effects include:

• Nausea, vomiting, diarrhea or constipation 2
• Skin rash (<5%) 2
• Transient bronchospasm (1-2%) 2

Important Considerations

• For cystic fibrosis, evidence is insufficient to recommend routine use of inhaled or oral N-acetylcysteine 2
• Charcoal administration may interfere with drug absorption, with up to 96% of the drug potentially adsorbed 4
• In acetaminophen overdose, the interval between ingestion and treatment with acetylcysteine is closely related to outcome 2
• Acetylcysteine has complex antioxidant and immunologic effects whose mechanisms are not completely understood 2

When administering acetylcysteine for any indication, clinicians should monitor for adverse effects while recognizing its generally favorable safety profile even when combined with other treatments 5.