Adefovir-d4 is the deuterium labeled Adefovir. Adefovir (GS-0393) is an adenosine monophosphate analog antiviral agent that after intracellular conversion to Adefovir diphosphate inhibits HBV DNA polymerase. Adefovir has an IC50 of 0.7 µM against HBV in the HepG2.2.15 cell line. Adefovir has good antiviral activity against several viruses, including HBV and herpesviruses[1][2][3].