Valganciclovir is an antiviral medication used to treat cytomegalovirus (CMV) retinitis in patients diagnosed with acquired immunodeficiency syndrome (AIDS). Valganciclovir is a prodrug of ganciclovir. After administration, valganciclovir is rapidly converted to ganciclovir in the intestine or liver by intestinal or hepatic esterases.Ganciclovir is transported into the blood and to the infected cells. It is then converted to the active form by a virus-encoded cellular enzyme, thymidine kinase, which catalyzes phosphorylation of ganciclovir to ganciclovir monophosphate. Ganciclovir monophosphate is converted into the diphosphate by cellular guanylate kinase then into the triphosphate by a number of cellular enzymes. Ganciclovir triphosphate inhibits the activity of DNA polymerase by competing with its substrate dGTP. Ganciclovir triphosphate also gets incorporated into viral DNA, but since it lacks the 3'-OH group which is needed to form the 5′ to 3′ phosphodiester linkage essential for DNA chain elongation, this causes DNA chain termination, preventing the growth of viral DNA. Less Viral DNA is transported into the nucleus, therefore, less viral DNA is integrated into the host DNA. Less viral proteins produced, fewer viruses can form.

Valganciclovir Pathway References