Like every living thing, HIV can reproduce itself. It does this inside CD4 cells. This involves many different stages. HIV drugs work by interfering with some of these stages.

The 6 classes of drugs are:

• Entry inhibitors. This includes fusion inhibitors and CCR5 inhibitors
• Nucleoside and nucleotide reverse transcriptase inhibitors (nukes or RTIs)
• Non-nucleoside reverse transcriptase inhibitors (non-nukes or NNRTIs)
• Integrase inhibitors (INIs)
• Protease inhibitors (PIs)
• Budding inhibitors and maturation inhibitors

Different drugs work at different stages of the HIV life cycle

• HIV uses CD4 cells as factories to make hundreds of copies of itself.
• Entry inhibitors work by stopping HIV getting into the CD4 cell.
• Nukes and non-nukes work by stopping one of the main ways HIV reproduces inside the CD4 cell.
• Integrase inhibitors work by stopping HIV from being integrated into the CD4 cell’s DNA (genetic material).
• Protease inhibitors work by stopping any new HIV from being cut into smaller, manageable proteins.
• Budding and maturation inhibitors work by making new HIV that leaves the cell unable to infect new cells.

Further reading

The 2011 i-Base/TAG pipeline report includes a chapter on antiretrovirals that includes a review of new drugs, combinations and drug classes in development.