First-line antiviral therapies for chronic hepatitis B. For all adults, adolescents and children (two years or older) for whom antiviral therapy is indicated, the nucleos(t)ide analogues that have a high genetic barrier to drug resistance – tenofovir disoproxil fumarate (TDF) or entecavir (ETV) are recommended as preferred regimens. TDF + lamivudine (3TC) or TDF + emtricitabine (FTC) are recommended as alternative regimens (where TDF monotherapy is not available).