A lawyer representing the widow of man who claims that Merck & Co.'s (MRK) Vioxx caused her husband's death argued on Tuesday that taking the pain reliever for one month was enough to cause the 53-year-old man's heart attack.

But Merck countered in opening statements at the first federal Vioxx trial that its extensive studies of the painkiller before introducing it in 1999 showed no evidence it caused heart attacks with short-term use, and that heart disease, not Vioxx, led to Richard "Dicky" Irvin's death.

Unlike the two previous state-level cases where Merck emerged with a loss and then a win after several weeks, the federal case before U.S. District Judge Eldon Fallon of New Orleans appeared to rush along at a headlong pace.

It took less than two hours to pick a jury of five men and four women, three of whom are alternates. Opening statements for the plaintiff — Irvin's widow, Evelyn Irvin Plunkett — took less than an hour and Merck's opening didn't take much longer. Testimony was expected to begin as well.

The case is in Houston rather than its original venue of New Orleans because of damage wrought by Hurricane Katrina.

Jurors will be asked to decide whether Vioxx contributed to the fatal heart attack Irvin suffered in May 2001. The 53-year-old manager of a wholesale seafood distributor in St. Augustine, Fla. had been taking the drug for about a month to alleviate back pain when his co-workers found him dead at his desk.

"There was nothing that would have triggered a fatal heart attack except for Vioxx," Plunkett's attorney Andy Birchfield told jurors.

This is the third trial Merck is facing over Vioxx's safety. It lost the first state trial in Texas last August, but scored a victory in its home state of New Jersey earlier this month.

Whitehouse Station, N.J.-based Merck withdrew Vioxx from the market in September 2004 after a long-term study showed the drug doubled risk of heart attack or stroke if taken for 18 months or longer. By then, more than 20 million Americans had used Vioxx.

Birchfield told jurors that Merck likes to cherry pick the 18-month hallmark to demonstrate that the drug could not have caused problems in patients who took it for a shorter time. But he told jurors a study showed Vioxx can cause problems after just seven days.

He said that Merck knew about Vioxx's safety problems before it was launched. Birchfield quoted from internal e-mails, including some from Merck scientists who raised warning flags about its cardiovascular risks, to support his assertions.

Merck made a "premeditated, financial decision" not to warn patients about the drug's risks because it wanted the revenue the former $2.5 billion seller would generate, and longed to beat Pfizer Inc.'s competing drug Celebrex in the marketplace, Birchfield said.

Merck's lawyer, Phil Beck, told jurors that Vioxx didn't trigger Irvin's heart attack and that the company acted responsibly at all times in its development and marketing of the drug.

"There is no evidence of short term use (of Vioxx) causing heart attacks," Beck said.

He spent the better part of his allotted hour for opening statements explaining to jurors how pain relievers work, and how Vioxx was a major advance because it was gentler on the stomach that other treatments such as aspirin.

"Mr. Irvin's problem was not that he took Vioxx, it was that he had coronary heart disease," Beck said.

Beck said coronary heart disease is common in men like Irvin — in their 50s and slightly overweight. He told the jury that in the sixty minutes he would talk, 60 people would die from clogged arteries. Beck added that Irvin had a particular type of plaque that was prone to rupture and to cause blood clots.

Birchfield had said during his opening that Irvin had 60 percent blockage in an artery, but that wouldn't have been enough to cause a heart attack.

Irvin's health status is expected to be a crucial factor in the trial.

In court filings, his widow says he was in "very good health" when he began taking Vioxx. Merck has noted that he received a Vioxx prescription from his son-in-law — an emergency room physician — without a checkup.

Also, Irvin's autopsy said he had moderate to severe clogged arteries, and a blood clot in a major coronary artery caused an irregular heartbeat and death.

Merck claims the clot formed when some of that plaque ruptured with no help from Vioxx. Plunkett alleges Vioxx — which inhibits an enzyme that promotes inflammation and thins the blood — led to the clot formation.

The company faces about 7,000 state and federal lawsuits and analysts have estimated its liability could reach $50 billion.