A recent Food and Drug Administration report says there is no conclusive evidence that someone taking Vioxx is at greater risk of a heart attack than someone taking other painkillers, a doctor testified Tuesday during the first federal lawsuit involving the drug.

Dr. David Silver, a Los Angeles rheumatologist who has received research grants from Vioxx manufacturer Merck & Co. (MRK), said because of that FDA document and several clinical studies, he does not believe Vioxx causes heart attacks.

"The FDA says it does not increase the risk at all ... and the overall benefits of Vioxx do outweigh the risks," said Silver, adding that Vioxx doesn't cause bleeding ulcers and other stomach problems the way earlier painkillers do.

The widow of Richard "Dicky" Irvin, 53, who died of a heart attack in 2001 after taking Vioxx for back pain for a month, is suing Merck. Evelyn Irvin Plunkett says Merck failed to issue warnings after studies showed the blockbuster painkiller could trigger cardiovascular problems. The plaintiffs' side rested its case Monday.

Merck, which began its defense late Monday, argues that problems with Vioxx surface after 18 months of use, not one month, and that Irvin's heart attack was caused not by the drug but by plaque that ruptured in his artery.

The April document from an FDA advisory committee says "data ... do not clearly demonstrate" that Vioxx increases heart attack risks. It says a small number of drug trials show Cox-2 inhibitors, including Vioxx, are associated with an increased risk of heart attacks than older painkillers, but "these observations raise serious questions."

Silver, the first defense witness, testified that he was not concerned with one 2000 study showing Vioxx users suffered five times as many heart attacks as users of the older painkiller naproxen. He said one explanation is that naproxen protects against heart attacks, not that Vioxx causes them.

Under cross-examination, Silver said he was a paid speaker for Merck and other pharmaceutical companies but insisted he was not biased.

Whitehouse Station, N.J.-based Merck pulled 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 taken Vioxx.

This is the first federal trial over Vioxx; Merck has lost one state trial over the drug and won another, but it still faces about 7,000 lawsuits. The Irvin case was moved to Houston from its original venue of New Orleans because of destructive Hurricane Katrina.