Generic AZT Hits the United States

The expiration of GlaxoSmithKline’s patent on AZT last month may be a watershed moment in the history of HIV therapy. Certainly not as great as the development of the first retroviral drug effective at controlling the virus, but maybe an important sign of things to come, both in treatment and research.

    On Sept. 19, FDA approved four different generic versions of Retrovir (zidovudine), known as AZT, manufactured by three different companies, for use in the United States.

    Although Retrovir was a comparatively low seller in 2004-thirteenth in the retroviral class, according to IMS Health-its patent expiration may create ripples in the market as well as incentives for research.

    Peter Young, president Young & Partners a specialized investment-banking firm, believes that HIV drugs losing their patents could drive innovation by creating financial incentives to develop cutting-edge therapies that dramatically improve treatment in order to get ahead of the generic alternatives.

    “It might end up being a very good thing because there is room for improvement to the extent that if people have patented new drugs that are very effective, they will be able to make money,” he said.

    In fact, most retroviral cocktails are re-combinations of familiar compounds, including AZT. When enough of these cocktails come off patent, they may create a useful lineup of generic drugs for patients who seek an alternative to high-priced branded therapies.

    “There is room for improvement in HIV/AIDS drugs,” Young said.

    The loss of revenues from Retrovir will not hurt GSK very much, however. Their AZT-containing cocktail Combivir was the top selling drug in market in 2004. It generated $3.1 billion dollars last year, in comparison to $36 million by Retrovir, according to IMS Health. GSK also has the fifth most profitable retroviral, Trizivir, which made $400 million. Trizivir also contains AZT.

    “The affect on GSK is going to be very modest,” Young said.

    He indicated that the vast number of HIV drugs available mean that one drug going off patent is not going to cause large drops in price throughout the market.

    “It’s not like other categories, like cholesterol, where three or four dominate,” he said.

    Generic AZT availability will help low-income people who must obtain the drugs through discount programs, usually sponsored by the government. Some advocacy groups, such as the AIDS Healthcare Foundation, have criticized GSK for extending AZT’s patent life through fixed-dose cocktail drugs Combivir and Trizivir.

    Manufactured by two Indian companies-Ranbaxy Laboratories Limited and Aurobindo Pharma LTD-and a subsidiary of Boehringer Ingelheim, Roxane Laboratories, the newly approved generics were already tentatively approved for use in developing countries under the President’s Emergency Plan for AIDS Relief.

    FDA claims these approvals indicate that drugs purchased under PEPFAR will be available to Americans when the patents on the brand versions expire.

    Right now there are eight tentatively approved PEPFAR products, according to FDA spokeswoman Karen Mahoney.