Patients taking the popular arthritis drug Vioxx have three times the risk of heart attack as people not taking the medication, new research suggests.
The study, funded by the US Food and Drug Administration, analysed the medical records of patients insured by one the largest health maintenance organisations in the US, California-based Kaiser Permanente. Among its members, 26,748 had taken Vioxx and 40,405 had used the rival drug Celebrex.
The study found Vioxx users had a 50 per cent greater chance of having a heart attack or sudden cardiac death than patients taking Celebrex.
The study found 8,199 heart attacks and cases of sudden cardiac death among the Kaiser members between 1999 and 2001.
The patients using Vioxx were taking 50mg a day, whereas in Australia the maximum dosage prescribed is 25mg.
The study’s authors said: “This and other studies cast serious doubt on the safety of high doses of Vioxx.”
Asked whether the FDA would consider banning the use of high-dose Vioxx, given the findings, the lead investigator for the trial, Dr David Graham, told CNN: “The FDA has to decide whether they think a three-fold increase of heart attacks outweighs the benefits of the drug.”
Linda Swan, medical director of Merck Sharpe and Dohme, which makes Vioxx, disputes the findings.
“Merck disagrees with the conclusions of this observational study,” Dr Swan said. “The results need to be put in context with the data that we’ve got from randomised controlled clinical trials.
“We’ve studied more than 24,000 patients and, based on that data, we stand behind the efficacy and overall safety profile of Vioxx.”
Ric Day, professor of pharmacology at the University of NSW and St Vincent’s Hospital in Sydney, said the study raised questions about how the medication was being used. “The advice locally about how to treat musculoskeletal problems is that you wouldn’t leap straight into using Vioxx.”
However, Vioxx was the sixth most commonly prescribed drug in Australia last year and between March 2003 and March 2004 there were 1.9 million prescriptions in the 25mg tablet form.
“There’s certainly too many prescriptions for this drug,” Professor Day said. “The Health Insurance Commission is currently running an education program for prescribers to remind them about what the restrictions for the prescription of these drugs are.”
Vioxx and Celebrex are both known as “Cox-2 inhibitors”, a type of drug that causes fewer gastrointestinal problems than older pain killers.
However, studies as far back as 2001 seem to suggest a link between the medication and heart problems. An article in the August 21 issue of the prestigious British medical journal The Lancet claims Vioxx, or rofecoxib, should carry greater product warnings. “The continued commercial availability of rofecoxib, without a black-box warning for cardiovascular patients, is indeed troubling.”
In 2003 Australia’s Adverse Drug Reaction Advisory Committee warned that there may be an increased risk of cardiovascular disease associated with this class of drug but said the evidence was inconclusive.