SamHep-TDF 300 mg Tablets SamHep-TDF contains Tenofovir Disoproxil Fumarate, an acyclic nucleoside phosphonate diester analog of adenosine monophosphate. Following absorption, it undergoes bioactivation to tenofovir and intracellular phosphorylation to active tenofovir diphosphate. Tenofovir diphosphate competes with natural substrates for binding to viral enzymes and is incorporated into viral DNA, resulting in DNA chain termination and inhibition of Hepatitis B virus (HBV) polymerase as well as HIV-1 reverse transcriptase. It is indicated for the treatment of chronic Hepatitis B virus infection in adults and pediatric patients, as well as for the management of HIV-1 infection in combination with other antiretroviral therapies.