Teva Invalidates Pfizer’s Viagra Patent in Canadian Supreme Court

The Canadian Supreme Court has accepted Teva’s contention that Pfizer’s patent for Viagra is invalid opening the way for Teva and others to produce and distribute generic versions of the drug. The Canadian ruling may be found here 

The reason that the patent has been invalidated is as follows:

In addition to a patentable invention being useful, new and non-obvious, there are formal requirements for the patent specification, which is required to be enabling. The patent specification is required to provide sufficient details to enable a person in the relevant field of endeavor to provide the invention without undue experimentation. In the US, until recently, there was an additional requirement to teach the best way to achieve the invention known to the inventors.

The problem with the Viagra patent is that the description and the claims as drafted cover astronomical numbers of compounds, of which only one, sildenafil has the effect of causing dilation of blood vessels, which enables its use for treating erectile dysfunction in males. The court therefore ruled the patent specification does enough information to allow another company to produce Viagra.

“Pfizer gained a benefit from the (Patent) Act – exclusive monopoly rights – while withholding disclosure in spite of its disclosure obligations under the act,” wrote Justice Louis LeBel. “As a matter of policy and sound interpretation, patentees cannot be allowed to ‘game’ the system in this way … (the patent) is invalid.”

Teva, Israel’s leading pharmaceutical manufacturer and the world’s leading generic drug manufacturer has been challenging the validity of Pfizer’s patent protecting Viagra for years. In the past, Pfizer has successfully Viagra in patent lawsuits from Teva in the New Zealand.  Norway  Spain, and the United States.

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