Valaciclovir (or valaciclovir) is an antiviral drug.
More precisely, valaciclovir is a prodrug, which means that - before carrying out its antiviral action - valaciclovir must be converted through hepatic metabolism into its active metabolite: aciclovir.
Valaciclovir - Chemical Structure
Valaciclovir is more absorbed from the gastrointestinal tract than its active metabolite aciclovir. Thus, oral administration of valaciclovir allows for higher plasma concentrations of aciclovir than would be achieved by administering aciclovir as such.