Zidovudine (AZT, Retrovir)

Zidovudine (AZT, Retrovir) is an anti-HIV drug that reduces the amount of virus in the body. Anti-HIV drugs such as zidovudine slow down or prevent damage to the immune system, and reduce the risk of developing AIDS-related illnesses.

Zidovudine belongs to a class of drugs known as nucleoside reverse transcriptase inhibitors (NRTIs). When HIV infects a cell, the enzyme reverse transcriptase copies the viral single-stranded RNA genome into double-stranded viral DNA. This viral DNA is then integrated into the CD4 chromosomal DNA and can go on to reproduce in the body. Four natural nucleosides complete the DNA synthesis: adenosine, cytidine, quanosine, and thymidine. An NRTI drug substitutes a defective version of one of the nucleosides, causing premature termination of the proviral DNA chain.

The drug is usually referred to by its generic name, zidovudine, which is abbreviated to ZDV. The abbreviation AZT is sometimes used, which stands for azidothymidine. Its chemical name is 3’-azido-3’-deoxythymidine.

Zidovudine is manufactured under the trade name Retrovir by GlaxoSmithKline. Retrovir was the first drug licensed to treat HIV infection, having been approved by the United States Food and Drug Administration (FDA) in 1987. GlaxoSmithKline’s patent on zidovudine expired in September 2005. Consequently, generic versions of the drug can now be sold in the United States and the European Union.

A generic version called Zidovir is manufactured by the Indian manufacturer Cipla. Other generic versions of zidovudine include Viro-Z (Ranbaxy), Aviro-Z (Ranbaxy) and Zido-H (Genixpharma).

Zidovudine is available combined with lamivudine in one pill, known by the trade name Combivir from GlaxoSmithKline. Each Combivir pill contains 300mg zidovudine and 150mg lamivudine. Generic versions of this co-formulation include called Duovir (Cipla), Virocomb (Ranbaxy) and a version made by Aurobindo Pharma.

A pill that combines 300mg zidovudine, 150mg lamivudine and 300mg abacavir, known as Trizivir, is also available from GlaxoSmithKline. It was approved in the United States in November 2000 and in the European Union in March 2001.