Which medication is classified as an antiviral for HSV or HZV?

Acyclovir is classified as an antiviral specifically targeting herpes simplex virus (HSV) and varicella-zoster virus (VZV), which is responsible for both chickenpox and shingles. It functions by inhibiting viral DNA polymerase, effectively stopping viral replication. This mechanism is particularly effective in reducing the severity and duration of herpes virus infections.

Acyclovir is commonly used for the treatment of conditions such as herpes labialis (cold sores), genital herpes, and shingles (herpes zoster). The drug is activated by being phosphorylated within infected cells, which enhances its selectivity for viral infections, minimizing toxicity to uninfected host cells.

The other medications listed serve different antiviral purposes. Trifluridine is an antiviral primarily utilized for ocular infections caused by HSV. Ribavirin is primarily used against respiratory syncytial virus and hepatitis C virus, not HSV or VZV. Amantadine is antiviral against influenza viruses and is not effective against herpes viruses. Therefore, Acyclovir is clearly the appropriate choice when specifically addressing infections from HSV or VZV.