Cidofovir (GS 0504, HPMPC, (S)-HPMPC) dihydrate is an acyclic monophosphate nucleotide analogue and CMV inhibitor with antiviral activity. Cidofovir dihydrate inhibits cytomegalovirus (CMV) replication by selectively inhibiting viral DNA polymerase. Cidofovir dihydrate induces apoptosis and can be used in studies of AIDS cytomegalovirus retinitis, herpes, and cancer[1][3]. Cidofovir dihydrate also has anti-orthopoxvirus and anti-variola activities[4].