Internal e-mails and other documents from Merck & Co. show the company fought for years to keep safety concerns from undermining the drug’s commercial prospects, the Wall Street Journal reported on Monday.

Vioxx, a drug known as a COX-2 inhibitor, was withdrawn from the market after it was shown to double the risk of heart attack and stroke in patients who had been taking it for at least 18 months. Vioxx generated some $2.5 billion in annual sales, and its withdrawal pummeled Merck’s shares.

On Monday, the Journal reported that an e-mail dated March 9, 2000, suggested Merck recognized that something in Vioxx was linked to increased heart risk.

Edward Scolnick, Merck research chief at the time, wrote in the e-mail that cardiovascular events “are clearly there” and called it a “shame.”

Although Scolnick compared Vioxx with other drugs with known side effects and wrote, “there is always a hazard,” the company’s public statements continued to reject the link between Vioxx and increased intrinsic risk.

Ted Mayer, a lawyer representing Merck, told the journal that the e-mails and marketing materials were “taken out of context” and “do not accurately represent the conduct of Merck and its employees.”

But a memorandum dated Nov. 21, 1996, by a Merck official illustrated that the company wrestled with Vioxx’s potential to induce a cardiac event, the report said. Another e-mail highlighted the possibility that patients could suffer blood clots unless they were also given aspirin.

Those documents may be used in ongoing litigation against the company.

On Friday, Merck - citing documents that had been made public - issued a statement saying that it acted “responsibly and appropriately” in developing and marketing Vioxx.

It was not immediately clear if it was referring to those obtained by the Journal, and a company representative was not immediately available to comment early Monday.