UPDATED: Pfizer faces growing legal threat over Lipitor

Sales of Lipitor, the best-selling drug of all time, may be waning, but litigation over the cholesterol fighter is growing--a lot.

A review by Reuters has found that the number of lawsuits by women claiming that Lipitor gave them Type 2 diabetes has grown to about 1,000, from just 56, 5 months ago. The huge run-up comes after a federal court consolidated the lawsuits into one jurisdiction, a move that often focuses the attention on an alleged problem.

Pfizer ($PFE) also appears to be a victim of its own success with Lipitor, which has been prescribed to more than 29 million people in the U.S., meaning there is a huge reservoir of potential plaintiffs for lawyers to draw from. It has also earned more than $130 billion since its approval, giving lawyers a large target to aim at.

This particular litigation harkens back to a label change the FDA ordered in 2012, just months after Pfizer lost the patent for Lipitor in the U.S. Makers of statins were told to add that the drugs could cause memory loss and other side effects, including a "small increased risk" of diabetes. Lawyers for the plaintiffs told Reuters that women face a higher risk than men of developing diabetes from using Lipitor without getting the same level of benefit.

Of course the burden is on the plaintiffs' lawyers to show that any cases of diabetes are linked to the drug and that the risks were greater than the benefit. Given that the FDA said at the time that the heart benefit of statins outweighs the "small increased risk" for diabetes, that could be difficult to prove.

Pfizer has denied that it dropped the ball in warning patients earlier and pledged to fight the lawsuits. In a statement Friday the company said it had always provided doctors with accurate information on both the risks and the benefits of Lipitor. "The safety and efficacy of Lipitor is supported by nearly two decades of research and more than 400 ongoing or completed clinical trials involving over 80,000 patients," Pfizer said.

The first case is set to go to trial next July, one of several bellwether cases that should give lawyers on both sides a feel for how juries see the evidence. That will then provide guidance on possible settlements.

Bayer settled about 3,000 cases for $1 billion in 2005 tied to its statin Baycol, which was linked to rhabdomyolysis, a disease that breaks down muscle tissue, Reuters reports. But there is a big difference. Bayer had pulled Baycol off the market in 2001 because it was tied to 31 deaths.

Lipitor remains on the market and remains a substantial seller for Pfizer, bringing in $2.3 billion last year, despite all of the generic statins that now compete. But it is a shadow of its former self. In 2010, the year before it lost patent protection, it brought in $10.1 billion.

- read the Reuters story

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