Arthritis drug linked to heart attack
Friday, 5 November , 2004
Reporter: David Hardaker MARK COLVIN: Class action lawyers are out in force in the United States over what they’re alleging is a cover-up surrounding a commonly used prescription drug. The drug is called Vioxx and is used to treat the symptoms of osteoarthritis and rheumatoid arthritis. In a report for the British medical journal the Lancet this week, researchers have said there was substantial evidence four years ago to show that Vioxx raised the risk of heart attacks. The US Food and Drug Administration recently published a study estimating that Vioxx may have caused 28,000 heart attacks since it was approved in 1999. The company which makes the drug disputes the findings of the Lancet research and says it has been vigilant in monitoring the drug. Nevertheless, the company withdrew Vioxx from the Australian market just on five weeks ago. David Henry is Professor of Clinical Pharmacology at the University of Newcastle he’s been conducting a study of the risks of Vioxx and other similar drugs. Our reporter David Hardaker asked Professor Henry if there was an increased risk of heart attacks and strokes amongst Australians who’ve used the drug. DAVID HENRY: Well, yes, I think there probably is. I think we’ve come to accept now, and the company has, that it causes increases the risk of strokes and heart attacks. What we don’t although we know that many people have been using the drug in this country, it’s been very popular as has the other similar drug, called Celebrex what we don’t know is to what extent people have been using higher doses of Vioxx in this country does seem to be what has been associated with an increased risk of thrombosis.
DAVID HARDAKER: How can this be, that we discover some years down the track that there may be a risk to a substantial number of Australians who’ve been using Vioxx? DAVID HENRY: Well, this is inherent in the way in which drugs are introduced, in this and other markets. The reason is that prior to marketing, only a relatively small number of people have been exposed to the drug, and there’s the tendency these days to try and get these drugs on the market early. So, much of the information about relatively uncommon adverse events, and this is an uncommon event, might only occur with a frequency of 1 in 1,000 these things escape detection prior to approval of the drug. So, there’s really a lot we don’t know about drugs at the time they come onto the market, and that makes it really important that we do studies after marketing, once drugs are actually used in the community. And unfortunately in Australia, we’re not very good at doing these studies, we don’t have systems to enable us to look quickly at whether the drugs are causing adverse effects. DAVID HARDAKER: Do you believe that the company or the Therapeutic Goods Administration does have questions to answer about the distribution of this drug in Australia?
DAVID HENRY: This question’s always asked whenever an adverse effect of a drug becomes known you know, should we have known earlier? With hindsight I think there were signs there, and as time has gone by, data have accumulated, we have a study ongoing on Australia, studying these effects as well, and it’s easy to be wise with hindsight. However, the study the initial studies weren’t absolutely conclusive, and then it’s a fine question about whether the benefits outweigh harms. Remember, this drug has advantages over some of the older drugs, in relation to its gastric effects. So, it’s quite a fine balancing act on this occasion, but I think the company was right to withdraw it. Once the effects were known, once it was known it caused thrombosis, it was right to pull it. What we don’t know is whether the high doses over 25 milligrams that have been associated with that effect were widely used in Australia. DAVID HARDAKER: And how many people are potentially affected by this? DAVID HENRY: Oh, in terms of using the drug, tens of thousands have been using it, but that doesn’t mean tens of thousands were actually at risk of thrombosis. It would only be a relatively a small proportion of these, but because it was widely used, it still might translate into a large number of individuals. As is say, I would stress we don’t know exactly who’s developed problems, and we don’t know how many were using the higher doses. MARK COLVIN: Professor David Henry of the University of Newcastle, speaking to David Hardaker. And the Therapeutic Goods Administration, which regulates drugs in Australia, says that Vioxx has only ever been approved here at lower doses 25 milligrams a day and that it published an adverse reactions alert about a year ago.