RICOVIR 300 Tablets RICOVIR contains Tenofovir Disoproxil Fumarate (TDF), an acyclic nucleoside phosphonate diester prodrug of tenofovir. Following oral absorption, TDF undergoes diester hydrolysis to tenofovir, which is subsequently phosphorylated by cellular enzymes into its active metabolite, tenofovir diphosphate. Tenofovir diphosphate competes with natural substrate deoxyadenosine 5'-triphosphate for incorporation into viral DNA by HIV-1 reverse transcriptase or Hepatitis B Virus (HBV) polymerase, causing DNA chain termination due to the lack of a 3'-OH group. It is indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection and as monotherapy for the treatment of chronic hepatitis B in adult and pediatric patients.