<s>[INST] context: Nonselective antiviral drugs: Ribavirin, Lamivudine, Adefovir dipivoxil, Interferon alpha Lamivudine (3TC): This deoxycytidine analogue is phosphorylated intracellularly and inhibits HIV reverse transcriptase as well as hepatitis B virus (HBV) DNA polymerase. Its incorporation into DNA results in chain termination. Most human DNA polymerases are not affected and systemic toxicity of 3TC is low. Point mutation in HIV reverse transcriptase and HBV-DNA polymerase gives rise to rapid lamivudine resistance. Ceain larnivudine-resistant mutants become slow growing. Some cross-resistance with ddl has been noted among HIV. Lamivudine is used in combination with other anti-HIV drugs, and appears to be as effective as AZT. It is also frequently used for chronic hepatitis B. HBV -DNA titre is markedly reduced and biochemical as well as histological indices of liver function improve. However, viral titres rise again after discontinuation. Even with continued medication HBV viraemia tends to return after 1 year due to emergence of resistant mutants. Dose: For chronic hepatitis B-100 mg OD For HIV infection- 150 mg BD ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:771,772 [/INST] question: Drug of choice for chronic hepatitis -B is | options: A: Lamivudine B: IFN-alpha C: Ribavirin D: Zidovudine | answer: A </s>