Pfizer just might postpone Viagra's patent cliff

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Could Pfizer get a reprieve on Viagra? It all depends on what happens in a federal trial beginning this week. As the Wall Street Journal reports, the company is trying to extend its exclusivity on the impotence drug by invoking a patent that doesn't expire till 2019. If affirmed, that patent would give up to seven years of extra oomph to Viagra sales.

Pfizer has been pursuing a variety of strategies to keep its Viagra franchise going. It has rolled out a new, chewable version in Mexico, for instance, and it's working on an over-the-counter version. But if it can win extended patent protection, that would be a major coup. Leerink Swann's Seamus Fernandez, who figures there's "a very good chance" Pfizer will get its extension, also figures that a longer Viagra monopoly would deliver "several hundred million dollars of sales and profits."

But before Pfizer can count those millions, it will have to fight off Teva Pharmaceutical Industries, which plans to launch its version of the drug after the basic patent expires next year. Teva has challenged the later patent, which covers the use of Viagra's active ingredient sildenafil as a treatment for erectile dysfunction. Originally under development as a heart drug, sildenafil is also sold under the Revatio brand name to treat pulmonary hypertension.

Pfizer says many of Teva's arguments against its 2019 patent have already been rejected by the U.S. Patent and Trademark Office, the WSJ reports. The PTO has examined and re-examined that patent already, the company says.

But Teva claims that using sildenafil for erectile dysfunction is obvious, and so the patent is invalid. Teva also claims that Pfizer engaged in "inequitable conduct" by withholding info from the patent office. As the WSJ notes, however, proving inequitable conduct just got more difficult after an appeals court ruling in a patent case involving Abbott Laboratories and Becton Dickinson. We can't pretend to be patent lawyers or psychics, so we'll have to wait till the court rules. The trial is expected to wrap next month, but a decision could be pending till early 2012.

- read the WSJ coverage

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