This medication is an antiviral agent of nucleosides group. Valacyclovir (valaciclovir) is the L-valine ester of acyclovir being thus a prodrug. After absorption into the blood valacyclovir almost completely converted to acyclovir under the influence of hepatic enzyme valacyclovir-hydrolase. In turn Acyclovir formed from valacyclovir affected by the virus penetrates cells where under the influence of the viral enzyme thymidine kinase converted into a monophosphate, then under the influence of cellular kinases - in the active diphosphate and triphosphate..Ref:   Lab. GlaxoSmithKline. Pain killer. Skin infections. Neuralgy. Genital herpes. Citomegalovirus. Zovirac