Different classes, of antiretroviral drugs target different stages of the HIV life-cycle. Two of the approved types of drugs - NRTIs and NtRTIs (usually considered as a single class) and NNRTIs - interfere with the action of HIV’s reverse transcriptase enzyme. Drugs in the protease inhibitor class block the action of the protease enzyme.

HIV entry inhibitors work in a various ways. There is one approved HIV fusion inhibitor and one approved CCR5 antagonist, but other types of entry inhibitors are under development. The first integrase inhibitor was licensed in 2007 and agents that target other steps of the HIV life-cycle are further back in the drug development pipeline.

For more information about all antiretroviral drugs licensed in the European Union, see NAM's drug chart.