The groups of antiretroviral drugs

There are five groups of antiretroviral drugs. Each of these groups attacks HIV in a different way.

Antiretroviral drug class	Abbreviations	First approved to treat HIV	How they attack HIV
Nucleoside/Nucleotide Reverse Transcriptase Inhibitors	NRTIs, nucleoside analogues, nukes	1987	NRTIs interfere with the action of an HIV protein called reverse transcriptase, which the virus needs to make new copies of itself.
Non-Nucleoside Reverse Transcriptase Inhibitors	NNRTIs, non-nucleosides, non-nukes	1997	NNRTIs also stop HIV from replicating within cells by inhibiting the reverse transcriptase protein.
Protease Inhibitors	PIs	1995	PIs inhibit protease, which is another protein involved in the HIV replication process.
Fusion or Entry Inhibitors		2003	Fusion or entry inhibitors prevent HIV from binding to or entering human immune cells.
Integrase Inhibitors		2007	Integrase inhibitors interfere with the integrase enzyme, which HIV needs to insert its genetic material into human cells.

NRTIs and NNRTIs are available in most countries. Fusion/entry inhibitors and integrase inhibitors are usually only available in resource-rich countries.

Protease inhibitors are generally less suitable for starting treatment in resource-limited settings due to the cost, number of pills which need to be taken, and the particular side effects caused by protease drugs.