The decision by the Texan courts could prove to be the most expensive legal action ever faced by a drugs company and raises ethical concerns about the marketing tactics used by a multibillion-pound pharmaceutical giant.
The landmark case found Merck responsible for the death of an American man who died in 2001 after taking Vioxx. Merck was ordered to pay his widow $253.4 million (€207.2 million) in damages after the jury heard testimony that Vioxx had been rushed on to the market without proper testing and that doctors had not been told of the potential risks of the drug.
Merck face more misery as they face the prospect of more than 4,000 sufferers from around the world, who have also lodged negligence claims against Merck. Industry analysts have predicted the company is likely to face a flood of cases that could cost the company more than $50bn (€40.9 billion).
Firms in London and Liverpool were understood to be representing at least 150 potential claimants, the BBC reported. In addition, lawsuits have also been filed in Canada, Europe, Brazil, Australia and Israel.
The outcome of this and pending cases could make-or-break the fifth largest drugs company. Whether it will survive as a strong, independent company or will be crippled for years or even decades by this scandal remains to be seen.
Vioxx, an arthritis drug that was prescribed to 400,000 patients in the UK, was taken off the market at the end of last September after a three-year trial linked it to an increased risk of heart disease events.
Merck described the court's decision as "disappointing," and said they would appeal the verdict.
"We believe that the plaintiff did not meet the standard set by Texas law to prove Vioxx caused Mr. Ernst's death," said Jonathan Skidmore of Fulbright & Jaworski, a member of Merck's defence team.
"There is no reliable scientific evidence that shows Vioxx causes cardiac arrhythmias, which an autopsy showed was the cause of Mr Ernst's death, along with coronary atherosclerosis," he added.
The eventual cost to Merck is likely to overshadow the litigation, which has so far cost Wyeth more than $21 billion over the diet drug combo fen-phen, which was linked to heart valve damage.