Teva’s Patent for Cenestin Under Threat due to File Wrapper Estoppel

Cenestin is a drug for the treatment of menopause symptoms, such as hot flashes and vaginal dryness. This prescription drug contains a mixture of synthetic estrogen hormones and works by replacing the estrogen that the ovaries no longer produce. It comes in tablet form and is taken once a day. Possible side effects include nausea, breast pain, and irregular vaginal bleeding or spotting.

Teva Women’s Health’s patent (the ’638 patent) is valid until 2015 but has been challenged by Watson Pharmaceuticals and by Paddock.

In an interesting development, Judge Leonard B. Sand of the U.S. District Court of the Southern District of New York granted Paddock summary judgment Tuesday, finding the doctrine of prosecution history estoppel prevented Teva from enforcing its patent.

Teva, as the world’s leading generic manufacturer, is used to going through patents with a fine tooth comb looking for problems.  They are less experienced with patent prosecution and it must be galling to have their patents declared unenforceable.



Categories: drugs, Intellectual Property, Patents, pharmaceuticals, Teva

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