Ganciclovir is an antiviral medication that primarily inhibits the replication of viruses, particularly cytomegalovirus (CMV). Its mechanisms include:
Phosphorylation to Active Form: Ganciclovir is initially phosphorylated by viral kinases (e.g., CMV UL97) to its monophosphate form and then further converted to its triphosphate form by cellular kinases. The triphosphate form is the active antiviral agent.
Inhibition of Viral DNA Polymerase: The active triphosphate form of Ganciclovir competitively inhibits viral DNA polymerase. By incorporating into viral DNA, it causes chain termination, thereby halting viral DNA synthesis and replication.
Selective Toxicity: Ganciclovir is selectively toxic to virus-infected cells because its initial phosphorylation is efficiently carried out by viral (not host) kinases, thereby reducing its impact on uninfected cells.
