HIV nucleoside reverse transcriptase inhibitors, commonly called NRTIs, are an important class of antiretroviral medicines used in combination HIV treatment. These medicines interfere with reverse transcriptase, an HIV enzyme needed to convert viral RNA into DNA. Common NRTI medicines include lamivudine, emtricitabine, abacavir, and zidovudine, while tenofovir is commonly classified separately as a nucleotide reverse transcriptase inhibitor.
HIV NRTIs are antiretroviral medicines that target reverse transcriptase, an enzyme HIV uses during its replication process. By interfering with the production of viral DNA, these medicines help prevent HIV from making new copies of itself. NRTIs are not usually used as a complete treatment by themselves. Instead, they form part of combination antiretroviral therapy, with the exact regimen selected according to current clinical guidance and individual circumstances.
NRTIs resemble the natural building blocks used to create DNA. After entering cells, they are converted into active forms that can interfere with HIV reverse transcriptase. When an active NRTI is incorporated into the growing viral DNA chain, further DNA extension can be stopped. This is often described as chain termination.
Important characteristics of NRTIs include:
Because HIV can develop resistance when antiretroviral treatment is ineffective or used improperly, treatment regimens are selected carefully. Combination therapy uses medicines with different mechanisms to suppress HIV replication more effectively.
Several medicines are associated with the NRTI class. Common examples include lamivudine and emtricitabine, while abacavir and zidovudine are other members of the class. Tenofovir disoproxil fumarate and tenofovir alafenamide are nucleotide reverse transcriptase inhibitors, but they are commonly discussed alongside NRTIs because they target the same general stage of HIV replication. NIH treatment tables distinguish these medicines according to their drug characteristics and classifications.
Examples include:
NRTIs commonly provide the backbone of combination antiretroviral therapy. For example, fixed dose combinations containing two NRTI or related agents can be combined with another antiretroviral class. NIH guidance lists combinations such as abacavir with lamivudine, tenofovir alafenamide with emtricitabine, and tenofovir disoproxil fumarate with emtricitabine or lamivudine. These products are not necessarily complete HIV treatment regimens and may need to be combined with another appropriate antiretroviral medicine.
Their treatment role can include:
Current HIV treatment guidance has increasingly emphasized integrase strand transfer inhibitor based regimens, while NRTIs or related nucleotide inhibitors may continue to provide an important component of combination therapy. WHO guidance also describes optimized NRTI backbones in specific treatment settings.
The choice of an NRTI containing regimen should therefore be individualized by a qualified healthcare professional. Factors such as previous antiretroviral exposure, resistance testing, kidney or liver function, pregnancy considerations, other medicines, and potential adverse effects may influence treatment selection. People should take HIV medicines according to their prescribed regimen and discuss any concerns about side effects or missed doses with their healthcare provider.