Pharmacology is a crucial part of medicine wherein various drugs are used to advance the well-being of an individual. Some drugs cure the infection or a disease; few prevent the occurrence of a symptom or a disease, and few are used in long-term treatment of the disease. Drugs are obtained from the plants as well as they can be synthesized organically. The drugs are used in various combinations or a single drug by the pharmaceutical industry during its preparation. The half-life of each drug is different, and the dosage of the drug depends on the half-life of the drug. The below information gives the detailed description of Emtri JUNIOR drug. Lamivudine (Emtri JUNIOR) (2′,3′-dideoxy-3′-thiacytidine, commonly called 3TC) is a potent nucleoside analog reverse transcriptase inhibitor (nRTI). It is marketed by GlaxoSmithKline with the brand names Zeffix, Heptovir, Epivir, and Epivir-HBV. Lamivudine (Emtri JUNIOR) has been used for treatment of chronic hepatitis B at a lower dose than for treatment of HIV. It improves the seroconversion of e-antigen positive hepatitis B and also improves histology staging of the liver. Long term use of Lamivudine (Emtri JUNIOR) unfortunately leads to emergence of a resistant hepatitis B virus (YMDD) mutant. Despite this, Lamivudine (Emtri JUNIOR) is still used widely as it is well tolerated.