Teva in bid to make generic version of Gilead's AIDS drug Truvada

AIDS drug maker Gilead Sciences Inc has said that Teva Pharmaceutical Industries Ltd intends to make a generic version of its top-selling drug Truvada.

Gilead said it received notice that Teva Pharmaceuticals is challenging two of its patents in its bid to manufacture a generic version of the HIV drug Truvada, even though threat seems to be at some distance.

Foster City, California-based Gilead said it is reviewing the notification letter from Israel-based Teva. Two of the patents associated with the drug are invalid, according to the letter. Gilead has 45 days to launch a patent infringement lawsuit to try and block Teva from manufacturing and selling a copy of Truvada, the statement said.

Teva has applied for permission from the US Food and Drug Administration (USFDA) to make a generic version of Truvada, which was the top- selling AIDS medicine in 2007, notching up $1.6 billion in revenues. Truvada is a combination of Gilead's drugs Viread, generically called tenofovir, and Emtriva or emtricitabine.

Truvada is covered by 10 patents, all of which will have to expire or become invalid for the company to lose its exclusive licence to make the drug, according to company spokesperson Cara Miller. The first patent is due to expire in 2010, while the last would expire around 2021. Reports suggested that a lawsuit would restrict approval of the generic drug for up to 30 months, or until a court ruling in favour of Teva, whichever is earlier.

1.Teva claims that two of the patents associated with emtricitabine, owned by Emory University and licensed to Gilead, are invalid or unenforceable.