Definition of AZT

AIDS Retrospective Slideshow

AZT: Zidovudine (formerly called azidothymidine [abbreviated AZT]), a drug used against human immunodeficiency virus (HIV), the virus that causes AIDS. The brand name is Retrovir.

The US Food and Drug Administration (FDA) approved AZT for the treatment of HIV infection. Current practice favors the use of AZT in combination with other drugs.

AZT is the pharmacologic mainstay for preventing the transmission of HIV by infected women to their babies during birth. In the U.S. AZT is now recommended for health care workers with needle stick exposures and cautiously suggested in rape cases in which there is a high risk of exposure to HIV. AZT crosses the blood-brain barrier and therefore may be effective against the syndrome of AIDS dementia.

AZT has some toxicity but for the 30-day time period it is used for PEP (post-exposure prophylaxis) there is an extremely low risk of long-term problems. The biggest issues (about AZT) are cost and uncertainty about efficacy, not its toxicity.

AZT acts as a nucleoside (thymidine) analog drug. It is in a class of drugs called reverse transcriptase inhibitors. Zidovudine is converted within the body to its active form (zidovudine triphosphate). This active form is similar to the compound thymidine triphosphate, a chemical needed by the HIV virus to make new DNA. The reverse transcriptase uses zidovudine triphosphate instead of thymidine triphosphate for making DNA, and it is the zidovudine triphosphate that interferes with the reverse transcriptase. Zidovudine does not kill existing HIV virus, and it is not a cure for HIV.