Valganciclovir hydrochloride (Valganciclovir HCl) is a hydrochloride salt form of valganciclovir, a prodrug form of ganciclovir, a nucleoside analog of 2'-deoxyguanosine, with antiviral activity. After phosphorylation, valganciclovir is incorporated into DNA, resulting in inhibition of viral DNA polymerase, and viral replication.

Valganciclovir is efficiently absorbed through the gastrointestinal tract, with its bioavailability approximately 60% when taken orally after meals. Upon administration, both intestinal and hepatic esterases concurrently hydrolyze the two enantiomers of ganciclovir, inhibiting the replication of human cytomegalovirus.

In cells infected with Cytomegalovirus (CMV), Valganciclovir is initially phosphorylated by viral protein kinase to its monophosphate form, then further phosphorylated by cellular kinases to produce its triphosphate form. This triphosphate is slowly metabolized within the cell. The phosphorylation process is dependent on viral kinase and preferentially occurs in virus-infected cells. Ganciclovir's antiviral activity is due to the triphosphate form of ganciclovir, which inhibits viral DNA synthesis. The ganciclovir triphosphate gets incorporated into the DNA, replacing many adenine bases, and hindering DNA synthesis as diester bonds take longer to form, thus diminishing the chain's stability.