When prescribing N‑acetylcysteine, what information is typically included in the medication order?

N-Acetylcysteine Prescribing Orders: Essential Components

When prescribing N-acetylcysteine, orders must specify the route of administration (oral vs. intravenous), precise dosing based on indication, infusion duration for IV formulations, dilution requirements, and total treatment duration. 1, 2, 3

Route-Specific Dosing Requirements

For Acetaminophen Overdose - Oral Route

• Loading dose: 140 mg/kg administered orally or via nasogastric tube, diluted to 5% solution 1, 2
• Maintenance doses: 70 mg/kg every 4 hours for 17 additional doses 1, 2
• Total duration: 72 hours (18 total doses) 2, 4
• Timing note: If presenting within 4 hours of ingestion, activated charcoal (1 g/kg) should be given just prior to starting NAC 1, 4

For Acetaminophen Overdose - Intravenous Route

The FDA-approved regimen requires three distinct phases with different concentrations and infusion rates 1, 3:

• Loading dose: 150 mg/kg in 5% dextrose over 15 minutes 1, 2, 3
• Second dose: 50 mg/kg over 4 hours 1, 2, 3
• Third dose: 100 mg/kg over 16 hours 1, 2, 3
• Total duration: 20 hours for standard protocol 2, 3

Critical dilution requirement: The product is supplied as 200 mg/mL (6 g/30 mL vials) and MUST BE FURTHER DILUTED prior to intravenous use 3

For COPD Exacerbation Prevention

• Standard dose: 600 mg orally twice daily 2
• Alternative dose: 600 mg once daily 2
• Target population: Patients with moderate to severe COPD and ≥2 exacerbations in the previous 2 years 2

For Contrast-Induced Nephropathy Prevention

• Dose: 1,200 mg orally twice daily for 2 days surrounding the contrast procedure 1, 4
• Critical caveat: Must be given together with intravenous isotonic crystalloid, never as a substitute for IV hydration 4

Essential Order Components by Indication

Acetaminophen Overdose Orders Must Include:

1. Route specification (oral vs. IV) with rationale—oral may be precluded by active GI bleeding or worsening mental status 1
2. Weight-based dosing calculations using actual body weight 1, 2
3. Dilution instructions for oral (5% solution) or IV (in 5% dextrose) 1, 3
4. Infusion rates and durations for each phase if using IV route 1, 2, 3
5. Monitoring parameters: Hemoglobin, hematocrit, and platelet count at least every 2-3 days for first 14 days 1
6. Baseline laboratory testing: CBC, renal and hepatic function panel, aPTT, and PT/INR 1

Common Pitfalls to Avoid

• Do not use previously opened vials for intravenous administration 3
• Do not delay treatment waiting for acetaminophen levels if overdose is suspected—initiate NAC immediately if ≤24 hours since ingestion 2
• Do not assume charcoal administration precludes NAC—up to 96% of NAC may be adsorbed by charcoal, but treatment should still proceed 5
• Do not discontinue early in established hepatic failure—NAC reduces mortality from 80% to 52% regardless of time since ingestion 2

Special Populations Requiring Modified Orders

• Extended-release acetaminophen formulations: Use standard dosing protocol but extend monitoring duration due to prolonged absorption 2
• Repeated supratherapeutic ingestions (>4g per 24 hours): Apply the standard 72-hour oral protocol 2
• High-risk patients (chronic alcohol users, fasting patients, baseline hepatic dysfunction): Initiate NAC even at lower acetaminophen levels 2
• Unknown time of ingestion: Administer NAC and assume potentially toxic overdose 2

Hypersensitivity Reaction Management Orders

Orders should include standing protocols for managing allergic reactions 1, 2:

• Discontinuation of infusion if severe reaction occurs 1
• Antihistamines for urticaria 1
• Epinephrine for bronchospasm 1, 2
• Note: Hypersensitivity reactions may occur during and after treatment, including hypotension, wheezing, shortness of breath, and bronchospasm 3

Storage and Preparation Notes for Orders

• Store unopened vials at controlled room temperature 20-25°C (68-77°F) 3
• Color change from colorless to slight pink or purple after stopper puncture does not affect product quality 3
• Maintain sterile technique throughout preparation to prevent contamination 6