Valaciclovir or valacyclovir is an antiviral drug used in the management of herpes simplex and herpes zoster . It is a prodrug, being converted in vivo to aciclovir. It is marketed by GlaxoSmithKline under the trade name Valtrex or Zelitrex. Valaciclovir is a prodrug, an esterified version of aciclovir that has greater oral bioavailability than aciclovir . It is converted by esterases to the active drug aciclovir via hepatic first-pass...