Pfizer Loses Viagra Patent in Canada

On Thursday, the Supreme Court of Canada struck down the patent on Viagra held by Pfizer and opened the floodgates to generic competition in the erectile dysfunction drug. Israel-based Teva Pharmaceutical Industries, which is the world’s largest generic drug manufacturer, had challenged Pfizer’s patent arguing that Pfizer’s filing was too vague. In a unanimous decision, Canada’s Supreme Court held that Pfizer had failed to provide sufficient details in the patent application to identify the actual active ingredient.

Writing on behalf of the 7-0 majority, Justice Louis LeBel observed, “Pfizer gained a benefit from the Act – exclusive monopoly rights – while withholding disclosure in spite of its disclosure obligations.” The court decided, “As a matter of policy and sound interpretation, patentees cannot be allowed to ‘game’ the system in this way … (the patent) is invalid.”

While Pfizer has won similar lawsuits by Teva in US, Spain, Norway, and New Zealand, in Canada at least, Pfizer’s monopoly over Viagra seems destined to end. Pfizer’s Canadian patent, which was scheduled to expire in 2014, included 260 quintillion different chemical compounds, but only one, sildenafil, was shown active, and the court said the patent provided insufficient information to allow another company to reproduce the drug.

The ruling opined, “Pfizer had the information needed to disclose the useful compound and chose not to release it … Even though Pfizer knew that the effective compound was sildenafil at the time it filed the application … it chose a method of drafting that failed clearly to set out what the invention was.”

Viagra sales of Pfizer have already been shrinking under competition from Eli Lilly and Co’s Cialis, which is supposed to have effects that last longer. While the loss of the Canadian patent may not create any immediate dent, it is bound to make a difference, as Viagra has annual sales of $2 billion and is Pfizer’s sixth-biggest medicine.