Indian drugmaker Aurobindo won approval on Friday for a capsule formulation of the HIV/AIDS drug zidovudine, as well as a provisional go-ahead for a co-packaged combination therapy for the infection.

Zidovudine started to lose patent protection in the USA last September, initially for the tablet and oral solution formulations of the drug. A number of generic versions of these forms have been approved for marketing. Now, following expiry of a patent on the capsule formulation, Aurobindo can offer all available oral formulations of the widely-used antiretroviral.

The compound was originally developed by GlaxoSmithKline, which sells it as Retrovir, although sales of the brand have plummeted as GSK has put its efforts into promoting combination products such as Trizivir (zidovudine, lamivudine and abacavir) and Combivir (zidovudine and lamivudine). GSK’s sales of Retrovir were just £41 million ($71m) last year, while Combivir made £583 million and Trizivir brought in £303 million.

“This is a significant generic approval,” said Dr Andrew von Eschenbach, acting Commissioner of the FDA. “Approval of this additional dosage form of zidovudine should help reduce the cost of this therapy for American patients.”

Meanwhile, Aurobindo won a tentative approval for a co-package of three antiretroviral drugs – a lamivudine/zidovudine fixed-dose combination and a generic tablet version Bristol-Myers Squibb’s Sustiva (efavirenz).

The approval is provisional, as existing patents prevent full registration of the product, so Aurobindo cannot yet launch it in the USA. However, the co-package could be purchased under the President's Emergency Plan for AIDS Relief (PEPFAR), set up in 2003 and providing $15 billion to fight HIV/AIDS in areas of the world hardest hit by the disease.

The FDA granted tentative approval for Aurobindo’s generic formulation of efavirenz last June, and for the fixed dose combination of lamivudine and zidovudine in July 2005.