Emtricitabine belongs to class of medication called antiretroviral medicines. It works by inhibiting the enzyme needed for DNA synthesis (nucleoside reverse transcriptase) thereby lowering the growth and decrease the amount of HIV in body.

Tenofovir is an antiviral drug belonging to class nucleoside reverse transcriptase inhibitors (NRTIs). Its structure closely resembles the natural structure of viral DNA, that helps it to incorporateitself into the viral DNA. By doing so, it blocks the activity of an important viral enzyme reverse transcriptase which is involved in the replication of viral DNA, a process essential for survival of the virus.

Efavirenz belongs to a class of antiretroviral medications called non-nucleoside reverse transcriptase inhibitors (NNRTIs). It inhibits the replication of HIV, thereby reducing the amount of the virus in the blood.