Tenofovir alafenamide fumarate (TAF) is a nucleotide reverse transcriptase inhibitor (NRTI) and a novel ester prodrug of the antiretroviral tenofovir. Following oral administration, TAF is converted in vivo to tenofovir, an acyclic nucleoside phosphonate (nucleotide) analog of adenosine 5′-monophosphate. Tenofovir mimics normal DNA building blocks but is lacking a 3'-OH molecule required for phosphodiester bond linkage. By competing with regular nucleotides for incorporation into proviral DNA and prevention of the formation of the 5' to 3' phosphodiester linkage required for DNA elongation, tenofovir causes early chain termination and prevents proviral DNA transcription.

It is used to treat hepatitis B infection.

The recommended dose of TAF is 25mg per day, 1 times a day.