The eleventh case to go to trial alleging Merck & Co covered up the dangers of its painkiller Vioxx has ended with a victory for the drugmaker.

The jury in the case, heard in New Orleans, concluded that Vioxx (rofecoxib) was not responsible for a heart attach suffered by 64-year-old Utah man Charles Laron Mason in July 2003, a little over a year before Merck pulled the painkiller off the market. The company was also found to have acted responsibly in reporting the risk with Vioxx once its link to heart attacks and stroke had been identified.

This is a good victory for Merck, as Mason had been on Vioxx for more than 10 months when he suffered his heart attack. The drugmaker has always maintained that exposure to Vioxx of 18 months or more is necessary to see an elevation in cardiovascular risk.

The company has been successful in defending itself in cases where short-term Vioxx use was involved, but has been tested when longer-term use of the drug is involved.

Merck said the verdict – its third of four victories in federal cases that have come to trial – is a further endorsement of its strategy to fight each case on its merits. And this view was supported by the judge in the case, Eldon Fallon, who said: “"plaintiffs have the burden of proving their claims and that is why we are addressing these cases on an individual basis.”

Mason’s case was undermined by the admission that he stopped taking Vioxx a few days before the heart attack, and also video evidence taken during an angioplasty procedure which showed that the affected artery was severely narrowed, with no evidence of a large thrombus, said Merck.

The plaintiff’s counsel countered that Vioxx’ labelling cites a risk of heart attack even during the two weeks after the drug is discontinued, but this failed to sway the jury.

Merck has now won six cases and lost four, with another victory overturned and five cases dismissed. It has set aside a $1.6 billion warchest for Vioxx’ defence, and as of October was facing nearly 24,000 lawsuits in the USA, as well as 275 class-action suits and an unspecified number of actions overseas.