LOS ANGELES — A California jury on Wednesday cleared pharmaceutical company Merck & Co. of liability in the case of an elderly man who claimed his heart ailments were caused by the drug maker's once-popular painkiller Vioxx.

After deliberating for about five hours in California's first trial over the drug, the 12-person jury determined that Merck was not negligent, did not conceal information and that Vioxx did not cause Stewart Grossberg's health problems.

"We didn't feel that a case was ever made that there is a connection between Vioxx and heart attacks," said jury foreman Charles Sullenger, 59. "In the end it simply boiled down to the burden of proof was not met in our opinion."

Jurors, however, agreed that there were potential risks for users taking Vioxx based on scientific studies.

Grossberg, 71, had sought compensatory and punitive damages, and more than $214,000 US for medical bills.

The two recent Merck victories bode well for the company at future trials because it shows that jurors are looking closely at the drug's effects on users, legal observers said.

"One of the messages that these two consecutive victories send is that juries are very receptive to the Merck argument that the drug isn't the problem with these older patients, it's their own illnesses," said Benjamin Zipursky, a professor at Fordham Law School in New York. "That strategy is obviously working fairly well in these cases."

The drug maker faces more than 16,000 lawsuits involving Vioxx, which was pulled from the market in September 2004 after a study found that it more than doubled the risk of heart attacks after 18 months use. In June, the New England Journal of Medicine published a correction to the study indicating the risk of heart problems was elevated before that 18-month period.

Merck has now won five Vioxx cases, including one last month in New Jersey, and has lost three. Another trial began this week in federal court in New Orleans.

In his lawsuit against Merck, Grossberg, who began taking Vioxx in 1999 to manage joint pain in his knees, hands and elsewhere caused by osteoarthritis, blamed the drug for his 2001 heart attack and a 2004 onset of angina, or chest pains.

Grossberg, a construction supervisor who lives in Northridge, Calif., sought damages on grounds that the drug caused his heart problems and accused the company of being negligent and of failing to warn users of the drug's dangers.

Grossberg's lawyer Jim O'Callahan said outside of court that he believed the jury form should have included whether Vioxx consumers - not just Grossberg's physician - were aware of its potential risks.

"We think there are issues there," O'Callahan said of the form. "We'll need to address them at future trials."

Merck, headquartered in Whitehouse Station, N.J., argued Vioxx had no role in Grossberg's heart problems.

"Merck is pleased with the jury verdict," Kenneth Frazier, the company's general counsel, said in a statement. "Today's outcome demonstrates, again, why we will defend these cases on a case-by-case basis."

Jurors heard from about 20 witnesses over four weeks. Many were medical experts who provided complicated testimony about pharmacology and medical statistics.

Grossberg testified last month that he used Vioxx for a number of years but took the painkiller "as needed" and not daily.

He said he took the drug during a pain flare-up and suffered a heart attack a few weeks later, which caused him to miss time from his job as a construction site supervisor.

Doctors placed a stent in one of his arteries and he was eventually released from the hospital and put on medication to reduce his lipid levels.

Grossberg resumed taking Vioxx two years later, but in late August 2004 decided to stop after hearing about problems with the painkiller. Three months later, he experienced chest pains and had a second stent placement.

Grossberg's right coronary artery had a 95 per cent high-grade lesion, according to his doctors. Plaque buildup also was present in other blood vessels - areas that had been normal in 2001.

Wednesday's decision comes three weeks after a New Jersey jury decided that Vioxx did not cause 68-year-old Elaine Doherty's heart attack. That case was the first in which jurors considered whether Merck failed to warn patients about the drug's cardiac risks.

More than 2,000 Vioxx lawsuits filed in California have been consolidated in Los Angeles by Superior Court Judge Victoria Chaney.