Merck & Co. said Friday it will pay $4.85 billion to end thousands of state and federal lawsuits over its painkiller Vioxx in one of the largest drug settlements ever. Company officials estimated the deal, if accepted, would end 45,000 to 50,000 personal injury lawsuits involving U.S. Vioxx users who suffered a heart attack or ischemic stroke, the type in which blood flow to the brain is blocked.

"Without this settlement, the litigation might very well stretch on for years," Merck executive vice president Kenneth Frazier said during a conference call. He called the agreement "responsible and reasonable" and allows Merck to better quantify its liability, once estimated as high as $50 billion.

Negotiating teams met more than 50 times in eight states and spoke hundreds of times by telephone over many months to hammer out the deal, according to attorneys. Merck pulled Vioxx from the market Sept. 30, 2004 after its researchers determined the blockbuster arthritis treatment, then pulling in about $2.5 billion a year, doubled risk of heart attacks and strokes.

Learn more about Vioxx injuries and the lawsuits that led to the Vioxx settlement.