Heart risks from taking Vioxx (rofecoxib) could have been detected more than three years prior to its withdrawal had the data been openly available, US researchers have said.
Further to an analysis of 30 studies on Merck & Co's painkiller there was "a trend toward increased cardiovascular risk" associated with Vioxx as early as December 2000. The study draws on clinical data from 1996 and 2004 involving more than 20,000 patients and compares rofecoxib to a placebo.
Merck voluntarily withdrew Vioxx from the market in September 2004 after a clinical trial found it to increase the risk of heart attacks and strokes in long-term users. In 2007, Merck settled Vioxx lawsuits for nearly $5m.
Dr Harlan Krumholz of Yale University School of Medicine worked on the study published in the Archives of Internal Medicine this week. He gained access to the data through his role as a paid witness for plaintiffs in lawsuits involving heart attacks or strokes that occurred after taking the drug.
Krumholz stated that "most of the information we are using in ths study was never published, or if it was published, they never included the key safety data."
Of the 30 studies, 18 were published before September 2004, when the drug was withdrawn, six were published after and six were never published.
The findings showed that by June 2001, Vioxx was associated with a 35 per cent increased risk of a cardiovascular adverse event or death, compared with a placebo. By April 2002, this had risen to 39 per cent, and by September 2004 – when the drug was withdrawn – by 43 per cent.
Merck spokesman Ron Rogers said: "There is nothing new here. We studied Vioxx before and after it was on the market… using more rigorous methods than these authors used and we didn't see any cardiovascular risk."
Krumholz stated that the study is not intended to 'point a finger' at Merck but to argue for better ways of tracking the safety of drugs once they are approved by the US Food and Drug Administration (FDA).