Merck suffered a double whammy of setbacks in its ongoing legal defence of Vioxx yesterday, after a New Orleans court awarded $51 million in compensatory and punitive damages to a man who claimed the drug caused his heart attack, and a judge in New Jersey ordered a re-trial in a case the drugmaker had already won.

Merck pulled Vioxx off the market in September 2004 after results from the VIGOR study showed the COX-2 inhibitor doubled the risk of heart attacks and strokes when taken for 18 months or more.

In the New Orleans case, the jury awarded the damages to 62-year-old Gerald Barnett, who claimed that Vioxx was directly responsible for a heart attack he suffered in 2002. Merck was found negligent in the case, which is the first federal trial that has not gone in the company’s favour.

Meanwhile, a New Jersey state judge vacated a verdict last year which cleared Merck of any wrongdoing in a case involving Frederick Humeston, who says he suffered a heart attack whilst taking Vioxx in 2001.

The judge presiding in the NJ case, Carol Higbee, has set a new trial date for January 16 on the grounds that an article published in the New England Journal of Medicine last December expressing concerns about the reporting of heart attacks in the VIGOR study. This constitutes new evidence which justifies a re-trial, she said.

Merck said it would appeal the verdict in the Barnett case, claiming the finding and the amount of damages awarded were “totally uncalled for.”

“We disagree with the jury's verdict. The plaintiff was at increased risk for a heart attack regardless of whether he was taking Vioxx," said Phil Beck of Bartlit Beck, Merck's lead trial lawyer in the case.

Merck said it is exploring several grounds for appeal, including insufficient evidence and the application of incorrect legal standards.

Shares in Merck were hit hard by the legal setbacks, closing down 6% at $38.83, largely because a series of wins supported Merck’s stated aim of fighting each case individually in order to minimise its liability. Each loss raises speculation that the company could be drawn into a broad – and expensive – settlement arrangement with the thousands of claimants seeking damages from Vioxx.

Analyst have suggested that Merck’s liability could be in the region of $50 billion.