Tenofovir disoproxil fumarate

Mechanism of action

Tenofovir disoproxil is a nucleotide analog reverse-transcriptase inhibitor (NtRTI). It selectively inhibits viral reverse transcriptase, a crucial enzyme in retroviruses such as human immunodeficiency virus (HIV), while showing limited inhibition of human enzymes, such as DNA polymerases α, β, and mitochondrial DNA polymerase γ. In vivo tenofovir disoproxil fumarate is converted to tenofovir, an acyclic analog of deoxyadenosine 5'-monophosphate (dAMP). Tenofovir lacks a hydroxyl group in the position corresponding to the 3' carbon of the dAMP, preventing the formation of the 5′ to 3′ phosphodiester linkage essential for DNA chain elongation. Once incorporated into a growing DNA strand, tenofovir causes premature termination of DNA transcription, preventing viral replication.