Nucleoside reverse transcriptase inhibitors (NRTIs) 

Nucleoside reverse transcriptase inhibitors (NRTIs) are active inhibitors of reverse transcriptase found in retroviruses such as the human immunodeficiency virus (HIV). The different nucleoside reverse transcriptase inhibitors may be activated differently but they have the same mechanism of action. NRTIs are activated generally by phosphorylation to the triphosphate form by cellular enzymes. It then competes with cellular triphosphates, which are substrates for proviral DNA by viral reverse transcriptase. NRTIs are used in the treatment of human immunodeficiency virus (HIV infection) and acquired immune deficiency syndrome (AIDS).

Nucleoside reverse transcriptase inhibitors (NRTIs) block reverse transcriptase (an HIV enzyme). HIV uses reverse transcriptase to convert its RNA into DNA (reverse transcription). Blocking reverse transcriptase and reverse transcription prevents HIV from replicating.

NRTIs are one of the types of antiretroviral drugs that treat HIV. They work by preventing the virus from multiplying in the body. For HIV especially, NRTIs work by blocking reverse transcriptase, the enzyme that HIV needs to replicate itself.

Nucleoside Reverse Transcriptase Inhibitors (NRTIs) inhibit reverse transcription by causing chain termination after they have been incorporated into viral DNA. For these drugs to be active they need to be phosphorylated intracellularly.