d4T (stavudine, Zerit)

d4T (stavudine, Zerit) is an anti-HIV drug that reduces the amount of virus in the body. Anti-HIV drugs such as d4T slow down or prevent damage to the immune system, and reduce the risk of developing AIDS-related illnesses.

Stavudine 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.

In May 1996, d4T was approved in Europe as a treatment for HIV in patients who had experienced failure of AZT (zidovudine, Retrovir) treatment or intolerance to AZT. It was approved in the United States in 1994. In August 1997, it received full approval as an initial therapy for the treatment of HIV-infected adults and children over three months of age with progressive or advanced immunodeficiency, when used in combination with other anti-HIV drugs. However, d4T has fallen out of favour as a drug for use in first-line therapy due to the increased risk of body fat side-effects. In June 2003, the British HIV Association recommended against the use of d4T in an initial anti-HIV drug regimen. In 2009, the World Health Organization recommended against the use of d4T because of its long-term, irreversible side-effects. 

d4T is manufactured by Bristol-Myers Squibb. It is also known as stavudine or by its trade name Zerit. Its chemical name is 2’,3’-didehydro-3’-deoxythymidine.