27th June 2023

Antiretroviral medications

There are five classes of antiretroviral medications used in HIV, which act on different parts of the HIV life cycle:

• Entry inhibitors (EI) – maraviroc blocks the CCR5 receptor to reduce viral entry to cells.
• Integrase inhibitors (II) – raltegravir, elvitegravir and dolutegravir inhibit the integrase enzyme which prevents the viral DNA from being joined to the host DNA.
• Protease inhibitors (PI) such as atazanavir, darunavir, ritonavir, lopinavir and fosamprenavir block the protease enzyme needed to form mature virions.
• Nucleoside reverse transcriptase inhibitors (NRTI) such as tenofovir, lamivudine, emtricitabine, abacavir and zidovudine act by replacing a nucleoside causing termination of DNA production from RNA by viral reverse transcriptase.
• Non-nucleoside reverse transcriptase inhibitors (NNRTI) such as efavirenz, etravirine, nevirapine and rilpivirine also act to inhibit reverse transcriptase.

The current recommendations for ‘therapy naïve’ adults with newly diagnosed HIV involve:

• NRTI ‘backbone’ with tenofovir and emtricitabine.
• A third agent – atazanavir/darunavir, dolutegravir, elvitegravir, raltegravir or rilpivirine (elvitegravir and rilpivirine are recommended only in circumstances of poor renal function and raised viral load, respectively).
• An alternative to the NRTI ‘backbone’ is abacavir and lamivudine, which are recommended only if there is a sufficient viral load and in HLA-B57:01 negative individuals.
• Patients are recommended to be started on antiretroviral therapy as soon as they are diagnosed with HIV.