Trials of the withdrawn arthritis drug Vioxx showed as early as four years ago that the medication could increase the risk of heart attacks and strokes, doctors say.

However, Australian and United States regulatory authorities did nothing to limit its use, instead accepting its American manufacturer Merck Sharp & Dohme's suggestion that the increased risk could be due to something other than Vioxx.

"In retrospect, it would have been better if systems had been put in place to further investigate the increased risk of cardiovascular events with rofecoxib (Vioxx) when these were first evident," doctors Paul Langton, Graeme Hankey and John Eikelboom said.

"Robust and consistent processes to suspect and actively examine such outcomes need to be established and implemented, particularly when life-threatening effects are possible with ... treatments for non-life-threatening conditions."

Vioxx, known generically as rofecoxib, was recalled in Australia and elsewhere on October 1 in the largest prescription drug withdrawal in history.

The withdrawal was prompted after a new study examining Vioxx's impact on bowel cancer found the drug caused an almost twofold increase in heart attacks and strokes.

The link to cardiovascular problems first appeared in a study conducted in 2000, the three Western Australian doctors wrote in an article to appear in next week's Medical Journal of Australia.

"It involved a fivefold increase in myocardial infarction (alone) and a twofold increase in myocardial infarction (heart attack), stroke or cardiovascular death among 8,076 rheumatoid arthritis patients treated for a median of nine months," they said.

Because patients on the trial taking another drug, naproxen, experienced no such increase, regulatory authorities accepted that naproxen was protecting people's hearts instead of questioning whether Vioxx was causing damage.

Further questions about the safety of Vioxx were raised in 2001, prompting the US Federal Drug Administration to require that the label be changed to highlight a potential increase in cardiovascular risk.

The experience showed drug manufacturers and regulatory authorities should ensure all existing and new drugs in the same class as Vioxx - known as coxibs - were safe, the doctors said.

"Pfizer, the manufacturer of (one such drug sold as) Celebrex, has recently announced that it will sponsor a major clinical study to reassess the cardiovascular safety of its product," they said.

Other coxibs include post-operative painkiller Dynastat and osteoarthritis drug Mobic.

The Age October 27, 2004 - 6:39AM

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