In Vitro: Cidofovir diphosphate tri triethylamine (0-1000 μM) inhibits HCMV, HSV-1, HSV-2, human α, human β and human γ DNA polymerase with Ki values of 6.6, 0.86, 1.4, 51, 520 and 300 μM, respectively.Cidofovir diphosphate tri triethylamine (0.3-30 μM) inhibits vaccinia virus DNA polymerase with a Km value of 23 μM.