For simple HSV keratitis, what is the typical oral antiviral regimen for 7 days?

• A. Acyclovir 800 mg five times daily for 7 days
• B. Valacyclovir 1 g twice daily for 7 days
• C. Acyclovir 400 mg five times daily for 7 days
• D. Famciclovir 500 mg three times daily for 7 days

Answer: (C)

For simple epithelial HSV keratitis, the goal is to suppress viral replication quickly and support healing with a regimen that achieves therapeutic drug levels in the cornea. Acyclovir, when given orally at 400 mg five times daily, provides reliable antiviral activity with a dosing schedule that maintains effective concentrations throughout the day. The drug is activated by viral thymidine kinase and then inhibits viral DNA polymerase, selectively targeting infected cells and reducing viral replication in the corneal epithelium. Seven days of this regimen aligns with the typical healing window for epithelial disease and offers a proven balance of efficacy and tolerability.

Other options use different antiviral agents or higher dosing frequencies, which are not the standard first-line regimen for simple epithelial HSV keratitis in this context, even though they may be appropriate in other settings.