What is the recommended dose of acyclovir (antiviral medication) for a 60kg male with viral meningitis?

Acyclovir Dosing for Viral Meningitis in a 60kg Male

For viral meningitis in a 60kg male, the recommended dose of acyclovir is 10mg/kg intravenously every 8 hours, which equals 600mg IV every 8 hours for 10-14 days. 1

Dosing Rationale and Considerations

Viral Meningitis Type Considerations

• HSV meningitis: 10mg/kg IV every 8 hours (600mg for a 60kg patient) for 10-14 days 1
• VZV meningitis: 10-15mg/kg IV every 8 hours (600-900mg for a 60kg patient) for 10-14 days 1

Weight-Based Dosing

• The dose should be calculated based on ideal body weight rather than actual weight, especially in overweight patients, to avoid toxicity 2
• For a 60kg male (assuming this is not significantly overweight), 10mg/kg equals 600mg per dose

Administration Schedule

• Administer intravenously every 8 hours
• Infuse over 1 hour to minimize risk of crystalluria and nephrotoxicity 3

Monitoring and Precautions

Renal Function Monitoring

• Monitor renal function regularly during treatment
• Acyclovir can cause nephrotoxicity through crystalluria and obstructive nephropathy 2
• If renal impairment develops, dose adjustment is required according to creatinine clearance:
  • CrCl 50-80 mL/min: No change
  • CrCl 25-50 mL/min: 10mg/kg every 12 hours
  • CrCl 10-25 mL/min: 10mg/kg every 24 hours
  • CrCl <10 mL/min: 5mg/kg every 24 hours 3

Neurological Monitoring

• Monitor for signs of neurotoxicity, which can manifest as confusion, hallucinations, seizures, or altered mental status 2
• Ensure adequate hydration to prevent crystalluria and subsequent nephrotoxicity 3

Treatment Duration

• For HSV meningitis: 10-14 days 1
• For VZV meningitis: 10-14 days 1
• Consider obtaining a repeat CSF PCR at the end of therapy if clinical response is inadequate 1
• If PCR remains positive, continue treatment until negative 1

Common Pitfalls to Avoid

1. Incorrect weight-based calculation: Using actual weight instead of ideal body weight in overweight patients can lead to overdosing and increased risk of toxicity 2

2. Inadequate hydration: Failing to maintain adequate hydration increases the risk of crystalluria and nephrotoxicity 3

3. Missed dose adjustments: Not adjusting the dose in patients with renal impairment can lead to drug accumulation and toxicity 3

4. Premature discontinuation: Stopping treatment before completing the full course can lead to treatment failure or relapse 1

5. Bolus administration: Administering acyclovir as a rapid bolus rather than as a 1-hour infusion increases the risk of crystalluria 4

By following these guidelines, the treatment of viral meningitis with acyclovir can be optimized to improve outcomes while minimizing the risk of adverse effects.