Key events involving the safety of Vioxx and other painkillers:

—May 1999: Food and Drug Administration approves Merck & Co.'s (MRK) Vioxx, a Cox-2 inhibitor, for treatment of arthritis and acute pain in adults.

—June 2000: Merck gives FDA results of VIGOR study, which shows Vioxx users suffered five times as many heart attacks as users of the older painkiller naproxen, sold under the brand name Aleve. Merck attributes the disparity to naproxen's heart-protecting qualities rather than a defect in Vioxx, but was rebuked by the FDA for making that assertion without scientific proof.

—September 2001: Merck receives a warning letter from the FDA about the company's post-VIGOR Vioxx promotional campaign "that minimizes the potentially serious cardiovascular findings" and "misrepresents the safety profile of Vioxx."

—April 2002: FDA changes Vioxx package insert to reflect VIGOR study results showing increased risk of heart attacks and strokes.

—May 2002: Carol Ernst sues Merck, alleging Vioxx triggered the May 2001 death of her husband, Robert Ernst, a 59-year-old Wal-Mart manager and marathon runner.

—Sept. 30, 2004: Merck voluntarily withdraws Vioxx from the market after halting a long-term study that it said showed Vioxx could double risk of heart attack or stroke if taken for 18 months or longer. The study, called APPROVe, had focused on whether Vioxx could prevent reoccurrence of colon polyps.

—February 2005: FDA panel concludes Vioxx and other similar drugs all pose heart risks, but the others should be available to consumers.

—Aug. 19, 2005: Texas jury finds Merck liable for the death of Robert Ernst, awarding his widow $253.4 million in damages. That will be reduced to about $26 million under Texas caps on punitive damages; Merck plans to appeal.

—Nov. 3, 2005: A jury in Atlantic City, N.J., rules Merck was not responsible for a heart attack suffered by Boise, Idaho, postal worker Federick "Mike" Humeston, who had taken Vioxx for about two months.

—Nov. 28, 2005: Squeezed by Vioxx lawsuits, tumbling revenues and other troubles, Merck announces it will eliminate 7,000 jobs and five production plants and revamp manufacturing in the first phase of a global reorganization.

—Feb. 17, 2006: In the first federal Vioxx case to go to trial, jurors in New Orleans cleared Merck in the death of Richard "Dicky" Irvin, who died after taking Vioxx for about a month. The verdict came on retrial after a federal judge in Houston three months earlier declared a mistrial when a jury failed to reach a verdict in the case.

—April 11, 2006: A jury in Atlantic City, N.J., split in a two-plaintiff trial, awarding damages to 77-year-old John McDarby, who suffered a heart attack after taking Vioxx, but absolved Merck in the case of 60-year-old Thomas Cona.

—April 21, 2006: A jury in Rio Grande City, Texas finds Merck liable in the death of Leonel Garza, a 71-year-old who had suffered from heart disease for 23 years and died after taking Vioxx for less than a month. The jury orders Merck to pay $32 million.

—May 11, 2006: Merck announces that follow up data from the APPROVe study show Vioxx users weren't at increased risk of heart attack or stroke in the year after stopping the drug, but prominent doctors says the data show risk was elevated for at least a year.

—June 26, 2006: The prestigious New England Journal of Medicine publishes a correction to the APPROVe Vioxx study indicating the risk of heart problems was elevated soon after people began taking the drug — not only after 18 months of use as Merck still contends.

—June 27, 2006: A Los Angeles Superior Court jury begins hearing the case of Stewart Grossberg, a 71-year-old Vioxx patient who had a heart attack in 2001 after taking Vioxx for 26 months.

—July 13, 2006: A jury in Atlantic City, N.J., rules Merck was not responsible for a heart attack suffered by Elaine Doherty, a 68-year-old diabetic homemaker who had been obese but lost nearly 100 pounds and improved her health years before the heart attack. The case was the seventh of at least 16,000 lawsuits to reach a verdict. It brings Merck's scorecard in the trials to four wins, three losses.