A lawyer representing a widow who claims that Merck & Co.'s 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, in which 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 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 D. Birchfield Jr. told jurors.

This is the third trial Merck is facing over Vioxx's safety. It lost the first state trial in Texas in August but scored a victory in its home state of New Jersey earlier this month. Altogether, the company faces about 7,000 state and federal lawsuits, and analysts have estimated its liability could reach $50 billion.

Whitehouse Station, N.J.-based Merck withdrew Vioxx from the market in September 2004 after a long-term study showed the drug doubled one's 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 cite the 18-month figure 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 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.

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, Philip 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.

Beck said coronary heart disease is common in men like Irvin who are in their 50s and slightly overweight. He added that Irvin had a particular type of arterial plaque that was prone to rupture and to cause blood clots.

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

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

Evelyn Irvin Plunkett leaves court in Houston. Her lawyers maintain that her husband died of a heart attack because he took Vioxx.