Drugs battles prove a headache for patent owners

The world's two biggest-selling drugs are at the centre of patent disputes that demonstrate the increasingly aggressive stance generic companies are taking against blockbuster drugs coming towards the end of their patent life.

Drugs company Pfizer stands to lose more than $10 billion in sales of its drug Lipitor, after the Court of Appeals for the Federal Circuit ruled on August 2 that one of the US patents protecting the blockbuster anti-cholesterol drug is invalid.

Meanwhile, Canadian generic company Apotex has begun to market a generic version of Sanofi's blockbuster anti-blood clotting drug Plavix, gambling that the courts will not enforce the Plavix patent in any future legal action.

In its decision on August 2, the Federal Circuit upheld the main patent covering atorvastatin, the active ingredient in Lipitor, which provides protection until March 2010. But the Court ruled that a second patent covering the calcium salt of atorvastatin, which would have lasted until June 2011, is invalid.

The decision is the latest in a fierce battle between Pfizer and Indian generic company Ranbaxy over patent protection for Lipitor, the world's biggest-selling drug. Sales of Lipitor this year are expected to be $13 billion worldwide, with $8.5 billion of that total coming from the US.

That means the Federal Circuit's decision could cost the New York company more than $10 billion, as Ranbaxy will be able to market its generic equivalent 15 months earlier than expected in the US.

Under US law, Ranbaxy would also have a 180-day head start on other generic producers.

In its opinion, the Federal Circuit said that claim 6 of the '995 patent is invalid, as it does not comply with Section 112 paragraph 4 of the Patent Act. This paragraph states that "a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers".

Specifically, the Court agreed with Ranbaxy that claim 6 of the patent failed to specify a further limitation of the subject matter of claim 2 as it was completely outside the scope of that claim.

Peter Richardson, Pfizer's senior vice president, associate general counsel and IP chief, said the company was disappointed with the decision on the '995 patent: "This decision turned on a technical defect in the patent. There is a process for correcting such defects at the US Patent and Trademark Office, and Pfizer plans to pursue that option."

Jay R Deshmukh, senior vice president, global intellectual property for Ranbaxy, said: "We are pleased by the Court's decision on the '995 patent and are evaluating our options with respect to the '893 patent."

Sanofi's Plavix is the world's second biggest-selling drug, with sales of $5.9 billion last year. It is sold in the US in association with Bristol-Myers Squibb (BMS)

Apotex's decision to bring its generic equivalent to the market in the US five years before the patent expires comes less than six months after it reached a deal with Sanofi and BMS to settle a legal battle being fought between the parties over the patent's enforcement and validity in the New York courts.

That deal was blocked by the US states' attorney generals, along with a modified agreement negotiated in June that would have given Apotex a licence to market its version of clopidogrel months before Sanofi's Plavix patent expires in 2011.

"There should be no mistaking that our decision to launch a generic version of this blockbuster product at risk is a testament to our commitment to patients, consumers and taxpayers," said Apotex's CEO Barry Sherman.

Sanofi and BMS have already filed an application in New York to block shipments of Apotex's version of clopidogrel. Hearings began on August 18. "Sanofi-aventis and Bristol-Myers Squibb continue to believe that the Apotex generic product infringes their IP rights, which are currently the subject of the pending patent litigation. The companies intend to continue to vigorously defend their patent rights against infringement," the companies said in a statement.

"This is a huge gamble on the part of Apotex. But companies are not poker players. They don't take a risk like that if they don't think it's worth it," said Kevin Noonan, a partner of McDonnell Boehnen Hulbert & Berghoff. He warned that Apotex's decision to enter the marketplace was "bold, arrogant and potentially very costly".