In a report for British medical journal The Lancet, researchers at the University of Berne said there was substantial evidence of the dangerous side effects of the drug by the end of 2000, but the mounting data was not analyzed properly.

The stunning verdict was certain to be greatly reduced under Texas law, but Merck's stock fell sharply as investors feared it could set a precedent for more than 4,200 lawsuits charging that the company hid the drug's health risks.

Merck pulled Vioxx off the market in September 2004, saying its long-term usage could double users' risks of heart attack or stroke.

Merck shares fell $2.35, or 7.73 percent, to $28.06 and put a damper on the Dow, which ended up just 4.3 points to 10559.23.

The case filed by widow Carol Ernst charged that Vioxx had caused her husband, Robert Ernst, a 59-year-old marathoner who took the drug for eight months, to die of a heart attack in 2001.

Merck disputed the accusation, saying an irregular heartbeat and clogged arteries killed Ernst, not Vioxx.

But the 12-member jury in Texas state court voted 10-2 that Merck should pay $24 million to Carol Ernst for mental anguish and loss of companionship and $229 million in punitive damages.

Merck attorney Jonathan Skidmore said the company would appeal the decision, but estimated that even if it is upheld the punitive damages would be trimmed to less than $2 million.

Texas law limits punitive awards to two times economic damage -- in this case $450,000 -- plus up to another $750,000. There is no financial limit for loss of companionship and mental anguish.

At the reading of the verdict in the six-week-long trial, the courtroom erupted in an uproar and Ernst broke into tears. Her lawyer, Mark Lanier, leaped up and shouted "Amen."

"They knew and could see what the truth was," she told reporters. "He (Robert Ernst) wouldn't have taken that pill everyday if he knew the risks."

Lanier urged Merck to settle the pending Vioxx lawsuits, not fight them. He vowed to file more lawsuits against Merck and "pound them again."

"Merck, you need to address this, you need to be responsible, you need to be accountable. You can't just use your money and your resources and run. At some point, the running stops," he said.

Merck general counsel Kenneth Frazier said the company would fight on, not settle.

"There are other Vioxx cases coming to trial, and we will vigorously defend them one by one over the coming years," he said.

Skidmore said Merck's appeal would be based on, among other things, scientific arguments.

"There is no reliable scientific evidence that shows Vioxx causes cardiac arrhythmia," he said.

Juror Derick Chizer, 43, said the jury, which deliberated almost two days, knew their award probably would be cut, but felt Merck needed a jolt to change its ways.

"That was a message to them," he said.

Another juror, Stacy Smith, 21, said she was shocked at evidence that showed the company knew the dangers of Vioxx long before they took it off the market.

"That was the main thing that stuck out to me - they knew and they still put it out anyway," she said.

The arthritis drug had been taken by about 20 million people at the time of its recall and contributed more than $2.5 billion in sales for Merck in 2003, about 10 percent of the company's total revenue.

Vioxx is the trade name for rofecoxib, part of a class of drugs called

NSAIDs. A type of painkiller known as a COX-2 inhibitor, it was touted as a pain and inflammation reliever that did not cause ulcers or gastrointestinal bleeding, a side effect of many NSAIDs.

Due to the pending lawsuits, Merck said at the end of last year it had set aside $675 million to help cover legal costs.

Another Vioxx trial is set to begin September 12 in New Jersey, where Merck is based.

Wall Street analysts, who have been closely watching the case in Angleton, a small town about 40 miles south of Houston, say Merck's legal woes will last for years and liability in all the cases could run into billions of dollars.

"It will cost them at least $1 billion a year for the next 10 years," said John LeCroy, an analyst at Natexis Bleichroeder.

Lawyer Jerry Reisman, a class action attorney in Garden City, New York, said the case also may prompt many more lawsuits.

"If the Ernst family is successful in this suit, Merck will find others piling on and joining class action suits," he said.

"This case can send shock waves through the pharmaceutical industry."

Defined

NSAIDs - Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used as painkillers and to treat arthritis. Many are available without prescription, for example, ibuprofen and aspirin. NSAIDs are useful and popular painkillers, but if they are used a lot or for a long time they can cause problems like stomach ulcers, and may damage the kidney. Please talk to your doctor if you are concerned about the effects of any of the medications you are taking, including those you buy yourself.

Vioxx - Rofecoxib is a nonsteroidal anti-inflammatory drug (NSAID) that was used in the treatment of osteoarthritis, acute pain conditions, and dysmenorrhoea. Formerly marketed by Merck & Co. under the trade names Vioxx, Ceoxx and Ceeoxx, it was voluntarily withdrawn from the market in 2004 because of concerns about increased risk of heart attack and stroke.