Acyclovir Dosing for HSV Meningitis
For adults with HSV meningitis, the recommended dosing regimen is intravenous acyclovir 10 mg/kg every 8 hours for 14-21 days with normal renal function. 1
Adult Dosing
- Intravenous acyclovir 10 mg/kg every 8 hours for 14-21 days is the standard treatment for HSV meningitis in adults with normal renal function 2, 1
- Treatment should be initiated as soon as possible, as early therapy (within 4 days of symptom onset) reduces mortality to approximately 8% 2, 1
- Dose adjustments are necessary for patients with renal impairment 2, 1
Pediatric Dosing
- For children 3 months to 12 years: 500 mg/m² intravenously every 8 hours 2
- For children >12 years: 10 mg/kg intravenously every 8 hours (same as adult dosing) 2
- In neonates, higher-dose acyclovir (20 mg/kg intravenously every 8 hours for 21 days) has shown improved outcomes with decreased mortality to 5% 2, 1
Treatment Considerations
- Intravenous therapy is mandatory for HSV meningitis requiring hospitalization rather than oral alternatives 1
- Treatment should be initiated within 6 hours of admission if CSF and/or imaging findings suggest viral encephalitis 2
- Even if initial CSF microscopy or imaging is normal but clinical suspicion remains high, acyclovir should still be started within 6 hours of admission 2
Monitoring Treatment Response
- Consider obtaining a repeat CSF specimen for PCR at the end of therapy in patients who have not had appropriate clinical response 2, 1
- If PCR remains positive for HSV at the end of treatment, antiviral therapy should be continued 2, 1
- Monitor renal function throughout treatment due to risk of nephrotoxicity from acyclovir 1
Special Populations
- Immunocompromised patients may have worse outcomes without antiviral therapy and benefit significantly from treatment 3
- 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 disease despite therapy), consider alternative treatments such as foscarnet (40 mg/kg IV every 8 hours) 1, 4
Potential Complications
- Relapse of HSV infection has been reported after completion of acyclovir therapy, with rates as high as 5% 2, 1
- Renal impairment can occur secondary to crystalluria and obstructive nephropathy, requiring careful monitoring 2
- The duration of treatment (14-21 days) is important to ensure adequate viral suppression and prevent relapse 1
While most immunocompetent patients with HSV meningitis recover without neurological sequelae 3, 5, prompt initiation of appropriate acyclovir dosing is essential to optimize outcomes, particularly in immunocompromised individuals and those with more severe disease.