Tenofovir blocks reverse transcriptase and hepatitis B virus infections.

Tenofovir is an analog of adenosine monophosphate that has antiviral activity.It is converted by cellular enzymes to tenofovir diphosphate, an obligate chain terminator that inhibits the activity of HIV reverse transcriptase and hepatitis B virus polymerase.Tenofovir diphosphate is a weak inhibitor of mammalian DNA polymerases α and β and mitochondrial DNA polymerase γ.For in vivo and cell culture use, tenofovir is supplied as a water soluble prodrug in the form of tenofovir disoproxil fumarate, which increases the intracellular diphosphorylated compound >1,000-fold above the level attained with unmodified tenofovir.