Hello, Zeffix otherwise known as Lamivudine is used in chronic hepatitis b infection and is also a nucleoside analogue. It is an antiviral medicine and used to treat Hepatitis B, which infects the liver and leads to liver damage. Once it is inside the liver it multiplies and involves DNA as well. This is achieved by VIRA DNA polymerase, which is an enzyme. Lamivudine (Zeffix) works by blocking the action of this enzyme and this stops the virus from multiplying. It lowers the amount of Hepatitis B virus in the body. This leads to a reduction in liver damage and an improvement in liver function. This medicine helps to control your Hepatitis B infection, but it is not known if it will cure it. That means you could be still at risk of transmitting the virus to other people through sexual contact or blood contamination. Your liver function should be monitored every three months, and the amount of Hepatitis B virus in your body should be monitored every six months. You should not stop taking this drug unless instructed by your doctor; otherwise your Hepatitis might get worse. If your doctor tells you to stop treatment, your liver function will need to be monitored for at least a further four months to check for any problems. So don't stop the medicine until your physician says so, even the laboratory reports (HBVPCR quantitative show results < 20 IU per ml). Hope this helps. Thank you