Acyclovir IV Dosing for Herpes Zoster Ophthalmicus (Shingles of the Eye)
For herpes zoster ophthalmicus requiring intravenous therapy, administer acyclovir 10 mg/kg IV every 8 hours for 7-14 days in patients with normal renal function. 1
When to Use IV Acyclovir
IV acyclovir is reserved for severe cases requiring hospitalization, including:
- Disseminated herpes zoster infection 1
- Immunocompromised patients with severe disease 1
- Patients with complications such as encephalitis, pneumonitis, or hepatitis 1
- Proven or suspected acyclovir-resistant strains (though these cases may require foscarnet instead) 1
Standard Dosing Protocol
The recommended IV dose is 10 mg/kg body weight every 8 hours (administered over 1 hour as an infusion) for 5-7 days or until clinical resolution is attained. 1, 2 This dosing applies to patients with normal renal function and must be adjusted for renal impairment. 1
Treatment Duration
- Minimum duration: 5-7 days for severe disease 1
- Treatment should continue until clinical resolution is achieved 1
- For immunocompromised patients, longer courses may be necessary 1
Transition to Oral Therapy
Once the patient stabilizes and can tolerate oral medications:
- Transition to oral acyclovir 800 mg five times daily to complete a 7-day total course 3
- A 7-day course is sufficient for herpes zoster ophthalmicus; extending to 14 days provides no additional benefit 3
- Oral therapy reduces late ocular inflammatory complications to 29% (compared to 50-71% in untreated patients) and postherpetic neuralgia to 13% 3
Alternative Oral Regimens (When IV Not Required)
For less severe cases that don't require hospitalization:
- Acyclovir: 800 mg orally 5 times daily for 7 days 3
- Valacyclovir: 1000 mg orally every 8 hours for 7 days (offers simpler dosing with equivalent efficacy) 4, 5
Critical Considerations
Timing is essential: Treatment must be initiated within 72 hours of rash onset for maximum benefit in preventing ocular complications and postherpetic neuralgia. 3
Renal dosing adjustments are mandatory: Acyclovir is renally cleared, and failure to adjust doses in patients with impaired renal function can lead to neurotoxicity. 1, 4
Immunocompromised patients may require higher doses or longer duration: Clinical experience suggests these patients benefit from more aggressive therapy, though the optimal regimen remains somewhat controversial. 1
Common Pitfalls to Avoid
- Do not use topical acyclovir alone - it is substantially less effective than systemic therapy 1
- Avoid topical corticosteroids in HSV epithelial infections as they potentiate viral replication, though they may be used with concurrent oral antivirals for stromal keratitis 6
- Do not delay treatment waiting for laboratory confirmation - initiate therapy based on clinical presentation within the 72-hour window 3