May 12 (Bloomberg) -- A U.S. judge has ruled that a “critical” expert witness in at least 20 pending lawsuits brought by plaintiffs who claim they were injured by taking Eli Lilly & Co.’s Zyprexa should be disqualified from testifying.

U.S. District Court Judge Jack B. Weinstein in Brooklyn, New York, said he will exclude the expert testimony of Dr. Stephen Hamburger. The doctor has offered testimony in some 20 individual Zyprexa cases, seven of which now have pending summary judgment motions before Weinstein, the judge said in a decision issued today.

Hamburger’s was “shockingly careless about the facts in the cases he proposes to opine about,” Weinstein said. The doctor gave conflicting answers to questions about the “claimed causal link between Zyprexa intake and medical injury,” he said.

“Faced under oath with consistent extensive factual discrepancies in his analysis, he merely shrugged them off or flippantly shifted to new theories,” Weinstein said. “He repeatedly and impermissibly stretched the truth to support findings of causality.”

The Indianapolis-based drugmaker had moved to prevent Hamburger from testifying as an expert witness in the cases. Zyprexa is approved to treat schizophrenia and bipolar disorder. The plaintiffs claim Lilly urged doctors to prescribe Zyprexa for uses not approved by the U.S. Food and Drug Administration.

$1.2 Billion

“We’re pleased with Judge Weinstein’s ruling,” Marni Lemons, a Lilly spokeswoman, said in a telephone interview.

In an April 30 filing, Lilly said it had settled suits involving about 32,670 claimants, with about 140 claims remaining. Most of these, about 100 plaintiffs, are combined, multi-district cases filed in New York and are pending before Judge Weinstein. Lilly has paid about $1.2 billion for the individual settlements, the company said in January.

“The record demonstrates that Dr. Hamburger’s opinions rely on a subjective methodology, a fast and loose application of his scientific theories to the facts,” Weinstein said in his ruling. “He cannot be allowed to testify because his opinions are neither ‘based on sufficient facts or data’ nor are they ‘the product of reliable principles and methods.’”

‘Disregard’ for Facts

Weinstein said Hamburger exhibited a “pattern of disregard” about the facts and theory don’t belong in a case involving claims of injury brought by multiple plaintiffs, such as those involving litigation claiming injury from asbestos exposure or breast implants.

“The court cannot permit a major pharmaceutical litigation to become the subject of the kind of ‘rubber-stamp’ expert opinions that have so marred mass litigations such as those involving asbestos and breast implants,” he wrote. To permit such testimony, Weinstein said, would negate “the utilization of science by the law.”

A lawyer for the plaintiffs, Don Ledgard, said, “We’re obviously disappointed and are considering our options for an appeal.”

Ledgard, of Capretz & Associates, said his firm represents 14 to 17 Zyprexa cases currently pending before Judge Weinstein. Ledgard said his clients’ claims of injury included weight gain and diabetes that stemmed from their use of the drug.

The case is In re. Zyprexa Products Liability Litigation, 04-MD-1596, U.S. District Court, Eastern District of New York (Brooklyn).

To contact the reporters on this story: Patricia Hurtado in New York at pathurtado@bloomberg.net; Margaret Cronin Fisk in Southfield, Michigan, at mcfisk@bloomberg.net.

Last Updated: May 12, 2009 20:00 EDT