More recently, AZT has been replaced by other antiretrovirals such as tenofovir to provide PEP.AZT is now a principal part of the clinical pathway for both pre-exposure prophylaxis and post-exposure treatment of mother-to-child transmission of HIV during pregnancy, labor, and delivery and has been proven to be integral to uninfected siblings perinatal and neonatal development. Without AZT, 10 to 15% of fetuses with HIV-infected mothers will themselves become infected. AZT has been shown to reduce this risk to 8% when given in a three-part regimen post-conception, delivery, and six weeks post-delivery. Consistent and proactive precautionary measures, such as the rigorous use of antiretroviral medications, cesarean section, face masks, heavy-duty rubber gloves, clinically segregated disposable diapers, and avoidance of mouth contact will further reduce child-attendant transmission of HIV to as little as 1–2%.During 1994 to 1999, AZT was the primary form of prevention of mother-to-child HIV transmission. AZT prophylaxis prevented more than 1000 parental and infant deaths from AIDS in the United States. In the U.S. at that time, the accepted standard of care for HIV-positive mothers was known as the 076 regimen and involved five daily doses of AZT from the second trimester onwards, as well as AZT intravenously administered during labour. As this treatment was lengthy and expensive, it was deemed unfeasible in the Global South, where mother-to-child transmission was a significant problem. A number of studies were initiated in the late 1990s that sought to test the efficacy of a shorter, simpler regimen for use in resource-poor countries.
The FDA approved the drug (via the then-new FDA accelerated approval system) for use against HIV, AIDS, and AIDS Related Complex (ARC, a now-obsolete medical term for pre-AIDS illness) on March 20, 1987. The time between the first demonstration that AZT was active against HIV in the laboratory and its approval was 25 months, the shortest period of drug development in recent history.AZT was subsequently approved unanimously for infants and children in 1990. AZT was initially administered in significantly higher dosages than today, typically 400 mg every four hours, day and night, compared to modern dosage of 300 mg twice daily. The paucity of alternatives for treating HIV/AIDS at that time unambiguously affirmed the health risk/benefit ratio, with inevitable slow, disfiguring, and painful death from HIV outweighing the drugs side-effect of transient anemia and malaise. Society and culture
In 1991, the advocacy group Public Citizen filed a lawsuit claiming that the patents were invalid. Subsequently, Barr Laboratories and Novopharm Ltd. also challenged the patent, in part based on the assertion that NCI scientists Samuel Broder, Hiroaki Mitsuya, and Robert Yarchoan should have been named as inventors, and those two companies applied to the FDA to sell AZT as a generic drug. In response, Burroughs Wellcome Co. filed a lawsuit against the two companies. The United States Court of Appeals for the Federal Circuit ruled in 1992 in favor of Burroughs Wellcome, ruling that even though they had never tested it against HIV, they had conceived of it working before they sent it to the NCI scientists.