The uses of Zeffix include: lamivudine, which is a type of medicine called a nucleoside analogue. Lamivudine is an antiviral medicine used to treat hepatitis B. (NB. Lamivudine is also used to treat HIV infection, but when used for this purpose, higher doses than those found in Zeffix are needed. See the Epivir factsheet for more information on this use of lamivudine.)
Hepatitis B is a virus that infects the liver and leads to liver damage. Once the virus is inside the liver cells it multiplies. Part of this process involves the virus making copies of its genetic material (DNA). This is achieved by a compound essential to the virus, called viral DNA polymerase. Viral DNA polymerase is a compound known as an enzyme. Lamivudine works by blocking the action of this enzyme. This stops the virus from multiplying.
Lamivudine lowers the amount of hepatitis B virus in the body. This leads to a reduction in liver damage and an improvement in liver function.