Types of antiretroviral drugs

There are five main types of antiretroviral drugs: 

• Nucleoside analogue reverse transcriptase inhibitors (NRTIs), which target an HIV protein called reverse transcriptase. Nucleotide analogue reverse transcriptase inhibitors (NtRTIs) work in a very similar way to NRTIs. 
• Non‑nucleoside reverse transcriptase inhibitors (NNRTIs), which also target reverse transcriptase, but in a different way to NRTIs and NtRTIs. 
• Protease inhibitors (PIs), which target an HIV protein called protease. 
• Fusion and entry inhibitors, these target the point where HIV binds onto cells of the immune system, or bind to the surface of HIV, and prevent the virus from attaching to human cells. 
• Integrase inhibitors, these target a protein in HIV called integrase, and stop the virus from integrating into human cells. 

Each class of drug attacks HIV in a different way. Generally drugs from two (or sometimes three) classes are combined to ensure a powerful attack on HIV.