"At this point in time," he said, "scientists should have started a public discussion about this potential trade-off, and designed studies that would more carefully evaluate the risk-benefit ratio of the drug."
"It appears from the internal Merck e-mails provided to me," he advised, "that in early 1997, Merck scientists were exploring study designs that would exclude people who may have a weak heart so that the heart attack problem would not be evident."
"Clinical trials should be designed to test a drug under "real world" circumstances - on patients who are most likely to use the drug," Dr Singh told the panel.
"Certainly," he continued, "clinical trials should not be designed to put marketing needs in front of patient safety - we need to know how a drug behaves in people who are going to take it, even if it "kills the drug".
Referring to documents provided to him by the Committee, Dr Singh said, "there were many other internal discussions within Merck on these concerns of heart attack-stomach bleed trade-offs, although the practicing physician did not learn of any of this till many years later," he added.
For instance, one document in 1998 authored by Merck scientist, Dr Doug Watson, presented an analysis of serious heart problems with Vioxx compared to patients enrolled in studies of other Merck drugs and concluded that in women, the risk of heart problems was more than double compared to people not taking any drug in other studies.
"To the best of my knowledge," Dr Singh said, "these data were never made public."
"This is when a public scientific discussion of the pros and cons of the medication should have started," he told the committee.
By 1999, he said, more serious problems were emerging. "By the time Merck had filed for the approval of Vioxx," he informed the panel, "there were several small studies evaluating the efficacy and safety of Vioxx in patients with pain and arthritis."
"None of these studies were large enough to study the risk-benefit trade offs of stomach bleeds versus heart attacks," he explained.
But in a careful review of Merck's FDA drug application for Vioxx, he told the panel, "Dr. Villalba noticed that "thomboembolic events are more frequent in patients receiving VIOXX than placebo"".
The review showed that among 412 patients taking a placebo, only one had a cardiovascular event; but among the 1631 patients receiving 12.5 mg or more of Vioxx, 12 had a cardiovascular event.
This meant that not only did Vioxx not inhibit the platelets, Dr Singh said, but for some reason, it was likely to promote heart attacks. "Many scientists would consider this three-fold difference as an early warning sign," he explained.
"It is my opinion," he told the panel, "that at this point in time, larger and more definitive studies should have been done before the drug was approved."
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