Viramune is the brand name for nevirapine, an antiretroviral medication. It is used to treat and prevent HIV/AIDS. The drug belongs to the class of non-nucleoside reverse transcriptase inhibitors (NNRTIs), which act by inhibiting a key enzyme the virus uses to replicate. When taken as part of a combination antiretroviral therapy, Viramune can reduce the viral load in patients and increase CD4 cell counts, improving the immune system's function.