Swiss researchers say Merck’s arthritis and painkilling drug, Vioxx – which can lead to heart attacks – should have been pulled off the market four years ago.
A new study shows that the dangers posed by Vioxx were apparent as early as 2000, but the drug was only withdrawn in September.
The results, published on Friday in the prestigious medical journal, the Lancet, are based on 29 separate studies, which highlighted the risks for patients using the blockbuster painkiller.
Altogether, information from 20,000 patients was included in this so-called meta-analysis.
“What we saw was that by the end of 2000, there was enough evidence pointing to a cardiovascular risk,” said Matthias Egger of Bern University. “Studies done after that time did not alter the overall picture.”
Egger believes that Merck should have withdrawn Vioxx from the market four years ago, as the information was readily available to the company and drug-licensing agencies.
“There was no reason they couldn’t have done the same analysis as we did,” he told swissinfo. “An independent commission should find out why this wasn’t done.”
The researchers’ conclusions were based on studies published in scientific journals as well as unpublished data from the United States Food and Drug Administration, which was obtained under the Freedom of Information Act.
The pharmaceutical company pulled the drug off chemists’ shelves only in September after a study revealed that Vioxx doubled the rate of heart attacks and strokes in patients who took it for more than 18 months.
The Bern researchers also criticised Merck’s interpretation of an earlier study, which compared Vioxx to another older painkiller, naproxen.
While heart attacks were at least four times more frequent for Vioxx users, its maker claimed this was due to naproxen having a protective effect on the heart.
But Egger and his co-author Peter Jüni said their work showed that there was no evidence of that naproxen had a protective effect. They added that the results of the 2000 study should have set alarm bells ringing at Merck.
They claim that Vioxx may have been given a more favourable evaluation than was appropriate because testing was carried out under Merck’s guidance.
Egger, who heads the department of social and preventive medicine at Bern University, says his research also showed that the risks of Vioxx were present irrespective of the dosage or period of use.
“Even small doses of Vioxx were associated with a risk of myocardial infarction,” he added.
The results contradict statements from Merck, which claims that the drug was only a danger to patients who took it for more than 18 months.
Egger’s analysis was already underway when Merck announced the withdrawal of the drug in September.
At the time, Egger and Jüni were considering whether to go public about the risks of taking the painkiller, but Merck’s decision forced them to move up their timetable.
“The editors at Lancet probably [decided] to publish this article on short notice because they felt there were important issues surrounding the withdrawal of Vioxx,” Egger told swissinfo.
“Possibly it will help clarify when Merck could have known about the risks related to this drug and also help us find out what happened.”
Merck is under heavy pressure from patients, the US Congress and the stock market following the withdrawal of Vioxx.
Hundreds of lawsuits have been filed against the company, which could stand to lose billions of dollars according to some financial analysts.
The Wall Street Journal also revealed earlier this week that internal e-mails and marketing material allegedly showed that the company knew about the risks associated with Vioxx back in 2000.
Merck said in a statement on Friday that it “was vigilant in monitoring and disclosing the cardiovascular safety of Vioxx, and the company absolutely disagrees with any implication to the contrary”.
The company said it also contested the conclusion that the drug should have been withdrawn several years ago.
swissinfo, Scott Capper
The Swiss study was funded by the National Science Foundation.
It is part of the “Chronic pain”programme, and was launched in April this year.
The so-called meta-analysis shows that Vioxx can cause heart problems no matter how small the dose taken or the duration of the treatment.
The results are published online Friday by the British medical journal, The Lancet.
In compliance with the JTI standards