The judge in the federal drug liability trial involving Merck & Co’s withdrawn painkiller Vioxx (rofecoxib) has declared a mistrial after the jury failed to reach a unanimous verdict on the case.

The news is a blow to Merck, which had been expected to win the case quite easily when the trial got underway. A win would have lent momentum to Merck’s campaign as it moves on to the huge number of outstanding lawsuits – almost 7,000 – that it still has to fight. Analysts have suggested the company could face liabilities of up to $50 billion dollars.

The lawsuit had been brought by Evelyn Irvin Plunkett, the widow of Richard Irvin, a 53-year-old man who died of a heart attack after taking Vioxx for about a month to relieve back pain. Merck argued that its drug was not responsible and that Mr Irvin had numerous underlying risk factors for a heart attack. The company believes that much longer exposure to the drug, in the order of 18 months, is required to raise the risk of a heart attack.

Perhaps sensing that chances of a victory were slim, the plaintiffs in the case asked for a mistrial, shortly after an editorial in the New England Journal of Medicine leveled serious accusations at Merck, including that it deliberately omitted and deleted data – including three heart attack cases - from a paper detailing the results of the VIGOR trial of Vioxx. The NEJM published the paper in 2000, three years before Merck withdrew Vioxx from the market because it was linked to an increased risk of heart attack.

An Associated Press report suggested that eight jurors had come down in favour of Merck, while one would not absolve the company of liability.

The drugmaker said it was happy to take the case back to the courts, saying it has ‘the resources and the resolve to address these cases, one by one’.

Three additional trials are due to begin next year on a monthly basis, starting in February 2006. The next trial, in New Jersey, is expected to be tougher call for Merck because the judge in the case has said it must involve patients with longer-term exposure to Vioxx.