Figure 1. Pharmacokinetics of aciclovir and valaciclovir. Valaciclovir (Val-ACV) is a prodrug of the antiviral compound aciclovir (ACV). Oral administration of valaciclovir yields systemic aciclovir through uptake by dipeptide transporters in the gut lumen and hydrolysis by esterases present in the gut lumen, intestinal wall and liver. >95% of administered valaciclovir is converted into aciclovir.