At least 300 British patients who claim to have suffered heart attacks and strokes as a result of Vioxx, as well as the relatives of others who died, are to sue the makers, Merck, for millions of pounds in the US courts. More than 4,000 sufferers from around the world have also lodged negligence claims against Merck, with experts warning that the company faces a " potentially unlimited" flood of cases that could cost it more than $50bn (£28bn).
Merck is accused of deliberately withholding information about the potentially fatal side-effects of Vioxx from regulators on both sides of the Atlantic and misleading doctors about the risks of the drug in its desire to rush its product on to the market. Evidence given to congressional hearings in the US has also revealed how sales representatives employed by Merck were told to dodge questions about the side-effects.
The case highlights the way pharmaceutical companies can distort scientific data on a product to exaggerate its benefits.
More than 20 million people, including 400,000 in the UK, took Vioxx before Merck withdrew it last September following a study suggesting that taking the drug for more than 18 months could double the risk of heart attacks in some people. Merck claims that the drug was thoroughly tested and has strenuously denied any wrongdoing.
The hopes of those suing have been buoyed by a ruling by a court in Texas last week that the drugs giant was responsible for the death of an American man who died in 2001 after taking Vioxx. Merck was ordered to pay his widow $253m 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.
British solicitors dealing with the class action said they were deluged with calls from more alleged victims over the weekend after details of the Texas case emerged. Russell Spargo, of MSB solicitors in Liverpool, which is dealing with 150 claimants, said: "This is a ticking bomb for Merck. The Texan case was seen as one of the weakest claims and Merck were convinced that they would win it. This could run into millions of pounds for the British victims alone."
Mr Spargo said American research estimated that more than 60,000 people may have died as a result of taking Vioxx a death toll greater than American fatalities in the Vietnam war. "This is a drug that should never have been marketed in the way it was."
The scale of the Vioxx case outstrips the Thalidomide scandal that led to the 1968 Medicines Act governing the way in which drugs are regulated. The Medicines and Healthcare Products Regulatory Agency (MHRA) which approves drugs in the UK, has launched an investigation into whether Merck deliberately withheld information on Vioxx when it applied for a British licence in 1999.
Documents in the Texas case alleged that officials at Merck knew as early as 1998 that the drug was linked to an increased risk of cardiovascular problems, but that the data was suppressed.
Vioxx was one of a new class of anti-inflammatory drugs called COX-2 inhibitors that were believed to be more effective than old-style painkillers, and with a reduced risk of ulcers and gastric problems.
Merck was competing with other drugs giants, including Pfizer, to bring the first COX-2 drug on to the market for treating arthritis and other conditions. The profits would have potentially run into billions of pounds, and the rival companies were spending millions on making and marketing their drugs.
Among allegations being investigated is the possibility that in the rush to beat Pfizer, Merck did not tell the US Food and Drugs Administration or the MHRA about the known risks of Vioxx. Nancy Santanello, a chief researcher for Merck, told the Texas trial the company's research unit had raised concerns as early as 1998 over the increased risk of heart attacks and strokes.
The punitive damages was equivalent to a 2001 estimate by Merck of the extra profit it would make if it could delay an FDA warning on the heart risks of its drug.Reuse content