Merck & Co. (MRK) didn't do any significant studies on whether Vioxx (search) could cause heart attacks or other serious cardiovascular problems before the popular painkiller went on the market in 1999, the company's top epidemiologist testified Wednesday.

Nancy Santanello (search), head of Merck's epidemiology department and the company's corporate face at the nation's first Vioxx-related lawsuit to go to trial, said nothing in Merck's database before the drug went on the market in 1999 indicated it could cause heart attacks.

"At that time we didn't think there was any risk," she said in her third day of questioning from plaintiff's lawyer Mark Lanier. She had yet to be questioned by the company's lawyers.

The plaintiff, Carol Ernst (search), alleges that her 59-year-old husband, Robert, died in his sleep in 2001 because he had taken Vioxx for eight months to ease pain in his hands. He died of an arrhythmia (search), or irregular heartbeat. Her lawsuit is the first to go before a jury of more than 4,000 pending in federal and state courts.

Merck has vowed to fight all the suits, claiming the company acted responsibly and believed Vioxx was safe until voluntarily pulling it from the market last year when a study showed the drug could double risk of heart attack or stroke. The company also contends no studies link Vioxx to arrhythmia.

Lanier contends Merck knew years earlier that Vioxx could be dangerous but needed the lucrative drug to keep its bottom line growing after patents for other big sellers ran out in 2000 and 2001. Santanello acknowledged under his questioning that Vioxx accounted for a dime of every dollar in Merck's $2.5 billion in sales in 2002.

In 2000 a study showed some Vioxx users could suffer five times as many heart attacks as those using the older painkiller naproxen — sold under the brand name Aleve.

In early 2002 Merck canceled a study intended to focus on Vioxx's effects on the heart.

"The company decided not to do the study?" Lanier asked.

"Yes, and there was a good reason for that," Santanello replied, but she didn't explain further as Lanier continued with other questions.

"There were good scientific and ethical reasons not to go forward with this test because the patients involved would have had to have their needed medications changed in order to produce a valid result," Kent Jarrell, spokesman for Merck's legal team, said outside of court.

Other such studies that began later ended abruptly when Merck took Vioxx off the market last year. One of those, dubbed VICTOR, began in 2003. Its preliminary results, which Lanier presented in an internal e-mail written more than five months after Vioxx was pulled, showed "statistically significant" serious blood-clot related cardiovascular problems, such as heart attacks.

"Don't you wish you started that study before you started selling pills to everybody?" Lanier asked.

"We did look at data," Santanello said. "We continued to investigate safety of product compared to placebo and other [non-steroidal anti-inflammatory drugs]."

Lanier asked if Merck was concerned, "why not wait until a bunch of people have died?"

"I was disagreeing with your assumption that we believed there was a problem," Santanello said.

When the Vioxx/naproxen study results came out in 2000, Merck attributed the disparity to naproxen's heart-friendly qualities rather than a defect in Vioxx. After two years of wrangling with the FDA, Merck added warnings about cardiovascular risks to the label in 2002.