Animation: NRTIs mechanism of action

Animation: NRTIs mechanism of action

NRTIs mechanism

Nucleoside analog reverse transcriptase inhibitors (NRTIs) are nucleoside analogues that act as competitive inhibitors of HIV-1 reverse transcriptase. As shown in the animation, these drugs compete with nucleoside triphosphates for access to reverse transcriptase.

All NRTIs lack a 3-hydroxyl group; thus, their incorporation into a growing DNA chain results in its termination. They require intracytoplasmic activation via phosphorylation by cellular enzymes to the triphosphate form. Most have activity against HIV-2 as well as HIV-1.

NRTIs mechanism of action

List of NRTIs

  • Zidovudine or azidothymidine (AZT) (also called ZDV): first approved drug in its class.
  • Didanosine (ddI): second FDA-approved drug for the treatment of HIV infection.
  • Tenofovir (TDF): first nucleotide analog. It has significant drug interactions.
  • Lamivudine (3TC): also used in the treatment of HBV infection.
  • Emtricitabine (FTC): acts as an inhibitor of HBV and HIV transcriptase.
  • Abacavir (ABC): a guanosine analog.

Animations depicting mechanisms of other antiretrovirals


Katzung, B. “Basic & Clinical Pharmacology”, 11th Edition. Mc Graw Hill Medical: 2009

Recommended reading

About the animation author

.Dr. Gary Kaiser is a Professor of Microbiology at The Community College of Baltimore County, Catonsville Campus located in Baltimore, Maryland. Make sure you visit his excellent microbiology website: The Grapes of Staph.


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