<|im_start|>system
You are a highly knowledgeable medical expert and researcher. Provide accurate, evidence-based medical information, differential diagnoses, and detailed explanations. Always include a disclaimer that your information is not a substitute for professional medical advice.<|im_end|>
<|im_start|>user
Question: Lamivudine is given when?
Options:
A. HBeAg positive
B. HBeAg negative
C. ALT >_ 2 ULN
D. Viral DNA> 10(square) copies
Which is the correct option?<|im_end|>
<|im_start|>assistant
The correct option is C: ALT >_ 2 ULN. Explanation: Lamivudine belongs to the set of antiviral agents effective against hepatitis B virus infection. Given case repos on liver injuries after ceain antiviral agent treatments, this study examined the effects of lamivudine on alanine aminotransferase (ALT) and total bilirubin (TB) using a medical system database Ref Harrison20th edition pg 2675 Lamivudine has been used for treatment of chronic hepatitis B at a lower dose than for treatment of HIV/AIDS. It improves the seroconversion of e-antigen positive hepatitis B and also improves histology staging of the liver. Long-term use of lamivudine leads to emergence of a resistant hepatitis B virus (YMDD) mutant. Despite this, lamivudine is still used widely as it is well tolerated Lamivudine, commonly called 3TC, is an antiretroviral medication used to prevent and treat HIV/AIDS. It is also used to treat chronic hepatitis B when other options are not possible.It is effective against both HIV-1 and HIV-2.It is typically used in combination with other antiretrovirals such as zidovudine and abacavir. Lamivudine may be included as pa of post-exposure prevention in those who have been potentially exposed to HIV. Lamivudine is taken by mouth as a liquid or tablet HIV, high level resistance is associated with the M184V/I mutation in the reverse transcriptase gene as repoed by Raymond Schinazi's group at Emory University. GlaxoSmithKline claimed that the M184V mutation reduces "viral fitness", because of the finding that continued lamivudine treatment causes the HIV viral load to rebound but at a much lower level, and that withdrawal of lamivudine results in a higher viral load rebound with rapid loss of the M184V mutation; GSK therefore argued that there may be benefit in continuing lamivudine treatment even in the presence of high level resistance, because the resistant virus is "less fit". The COLATE study has suggested that there is no benefit to continuing lamivudine treatment in patients with lamivudine resistance. A better explanation of the data is that lamivudine continues to have a paial anti-viral effect even in the presence of the M184V mutation. In hepatitis B, lamivudine resistance was first described in the YMDD (tyrosine-methionine-aspaate-aspaate) locus of the HBV reverse transcriptase gene. The HBV reverse transcriptase gene is 344 amino acids long and occupies codons 349 to 692 on the viral genome. The most commonly encountered resistance mutations are M204V/I/S. The change in amino acid sequence from YMDD to YIDD results in a 3.2 fold reduction in the error rate of the reverse transcriptase, which correlates with a significant growth disadvantage of the virus. Other resistance mutations are L80V/I, V173L and L180M Ref Davidson 23rd edition pg 768<|im_end|>
