Acyclovir Dosing for HSV Meningitis
The recommended dose of acyclovir for the treatment of herpes simplex virus (HSV) meningitis is 10 mg/kg intravenously every 8 hours for 14-21 days. 1
Dosing Recommendations
- For adults with HSV meningitis, acyclovir should be administered at 10 mg/kg intravenously every 8 hours with normal renal function 1
- Treatment duration should be 14-21 days to ensure adequate viral suppression and prevent relapse 1
- Therapy should be initiated as soon as possible after symptom onset, as mortality decreases to 8% if treatment begins within 4 days of symptom onset 1
- Dose adjustments are necessary for patients with impaired renal function 1
Clinical Considerations
- Distinguishing between HSV meningitis and encephalitis is crucial, as encephalitis represents a more severe condition requiring aggressive treatment 2
- HSV encephalitis has high mortality rates (up to 70%) without appropriate therapy, making prompt diagnosis and treatment essential 3
- In neonates, higher-dose acyclovir (20 mg/kg intravenously every 8 hours for 21 days) has shown improved outcomes with decreased mortality to 5% 1, 4
- For severe cases requiring hospitalization, intravenous therapy is mandatory rather than oral alternatives 1
Treatment Response Monitoring
- Consider obtaining a repeat CSF specimen for PCR at the end of therapy in patients who have not had appropriate clinical response 1
- If PCR remains positive for HSV at the end of treatment, antiviral therapy should be continued 1
- Relapse of HSV infection has been reported after completion of acyclovir therapy, with rates as high as 5% 1
Special Populations
Immunocompromised Patients
- Immunocompromised patients may require higher doses of antiviral medications 1
- For HIV-infected patients with severe HSV disease, acyclovir 5 mg/kg IV every 8 hours is recommended 1
- If acyclovir resistance is suspected (persistent lesions despite therapy), alternative treatments such as foscarnet (40 mg/kg IV every 8 hours) should be considered 1, 5
Recurrent HSV Meningitis
- For recurrent HSV-2 meningitis (Mollaret's syndrome), valacyclovir 500 mg twice daily has not been shown to prevent recurrent episodes 6, 7
- Treatment of acute episodes should follow the same guidelines as initial episodes 7
Potential Complications and Monitoring
- Monitor renal function throughout treatment, as acyclovir can cause nephrotoxicity 1
- Monitor complete blood count, as neutropenia can occur with high-dose acyclovir therapy 4
- Approximately 21% of patients receiving high-dose acyclovir may experience neutropenia, which typically resolves during or after completion of therapy 4
Alternative Administration Methods
- Continuous infusion of acyclovir has been explored as an alternative to thrice-daily dosing, particularly for outpatient therapy, though this is not standard practice 8
The evidence strongly supports intravenous acyclovir at 10 mg/kg every 8 hours for 14-21 days as the standard of care for HSV meningitis, with treatment initiated as early as possible to improve outcomes 1.