By Brian Bujdos

There are some rumblings and grumblings in the legal world about generic Viagra. It seems that five drug companies are ganging up on Pfizer, the manufacturer of Viagra, in order to bring their generic versions of Viagra to market before Pfizer’s Viagra patents expire. One expires on March 27, 2012, and another expires on Oct. 22, 2019.

In fact, Pfizer filed a complaint for patent infringement against four of the companies in a New York court on Oct. 29, 2010. The involved parties are Activis (based in India) and Apodex (based in Canada), as well as U.S.-based Mylan and Amneal.

All four of the above companies filed Abbreviated New Drug Applications (ANDAs) with the FDA earlier this year. The first company to do so, however, was Teva (the world’s largest manufacturer of generic drugs, based in Israel), which also met similar resistance from Pfizer.

Pfizer’s complaint seeks to protect itself from patent infringement, and ultimately the release of generic Viagra into the U.S. market before October 22, 2019. Pfizer claimed on page six of the 16-page complaint that the Orange Book (the official FDA publication that provides approved therapeutic drugs and their patent expiries) lists the ‘012’s patent expiration date as October 22, 2019.

This language in interesting, and could be a point of contention, however. This is because the 2012 patent is for the chemical entity of the drug (sildenafil citrate, which can easily be reverse engineered by drug companies). The patent that the drug companies are challenging is the 2019 patent, which deals with the method of use of Viagra/sildenafil citrate.

According to one law student at the American University Washington College of Law, method-of-use patents are generally considered to be weaker than composition patents. In his intellectual property brief at IPBrief.net, he stated that an analysis of the relative strength of Pfizer’s method-of-use patent is not yet available. However, the strength of that patent in the court system appears to be what all of this legal wresting will boil down to.

There’s a lot at stake as Pfizer sold $1.89 billion worth of Viagra in 2009. The company would obviously like to maintain its spot atop the erectile dysfunction (ED) pill market for as long as possible. Currently, Viagra controls a little less than 50 percent of the market, Cialis controls more than 40 percent ($1.56 billion in 2009) and Levitra controls about 10 percent. These are the only three FDA-approved medications for ED.

However, once generics are introduced to the U.S. market, the prices for ED drugs are expected to drop. Pfizer and the other brand-name ED pills will then lose much of their market share to the cheaper sildenafil citrate pills. Read more about what will happen when the Viagra patents expire.

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