VALTEN 300 mg Tablets VALTEN contains Tenofovir Disoproxil Fumarate (TDF), an acyclic nucleoside phosphonate diester prodrug of tenofovir. Upon oral administration, TDF undergoes rapid intracellular hydrolysis to tenofovir, which is phosphorylated to its active form, tenofovir diphosphate. Tenofovir diphosphate competes with natural deoxyadenosine 5'-triphosphate for incorporation into viral DNA via HIV-1 reverse transcriptase or Hepatitis B Virus (HBV) polymerase, terminating DNA chain elongation due to the lack of a 3'-OH group. It is indicated in combination with other antiretroviral agents for HIV-1 treatment and as monotherapy for chronic hepatitis B.