Which antiviral medication is often used as a first-line treatment for herpes simplex virus infections?

Acyclovir is recognized as a first-line treatment for herpes simplex virus (HSV) infections because it specifically targets the viral replication process. As a nucleoside analog, Acyclovir is phosphorylated by the herpes virus-specific enzyme thymidine kinase, becoming a competitive inhibitor of viral DNA polymerase. This inhibition halts the replication of viral DNA, effectively controlling the infection.

The effectiveness of Acyclovir has been well-documented in clinical settings, where it not only reduces the duration and severity of herpes outbreaks but also decreases the frequency of recurrences. It is particularly beneficial in treating both initial and recurrent episodes of genital herpes, and it can also be used in various forms such as intravenous or topical preparations, depending on the clinical situation.

Other options are not appropriate first-line treatments for herpes simplex virus. For instance, Ribavirin is primarily used for treating hepatitis C and some viral hemorrhagic fevers, while Tenofovir is an antiviral used to treat HIV and hepatitis B rather than HSV. Darunavir is a protease inhibitor utilized in HIV therapy and lacks efficacy against herpes viruses. Thus, Acyclovir remains the primary choice due to its targeted action against HSV.