Canadian regulators say they lack the power to force drug companies to research specific safety concerns once a medication is on the market, despite the suspicion of heart-attack risk that swirled around Vioxx and other painkillers for years.
Mark Bethiaume, director of Health Canada's marketed pharmaceuticals division, said those who feel the department failed to protect the public from the dangers of Vioxx and other cox-2 drugs misunderstand Health Canada's abilities.
He said Health Canada cannot compel a company to investigate a specific safety question after its drug has been approved for sale -- and the department lacks the resources to conduct its own trials.
"The way the Food and Drugs Act is written . . . we can ask for all the data [companies] have before a drug is approved," he said.
"Once the drug is approved . . . we can ask them to provide us further information about safety concerns, and if they don't comply with that, basically our only alternative is to withdraw the product from the market."
Health Canada cannot mandate a company to conduct a clinical safety trial, Dr. Bethiaume said, yet it has to have significant evidence to take a drug off the market.
Health Canada declined to say what action, if any, it tried to take in respect to Vioxx, citing lawsuits that have been filed in connection with the department's handling of the case. Merck Frosst Canada, the Canadian branch of the painkiller's manufacturer, Merck & Co., has said too that it would not answer questions related to its actions surrounding Vioxx because of legal concerns.
A Globe and Mail investigation published this weekend raised serious questions about whether drug regulators lacked the will or the regulatory tools to have Merck & Co. explicitly investigate the cardiovascular risks linked to its blockbuster drug Vioxx, which the company pulled from world markets last year after finding it doubled the risk of heart attack and stroke.
John Hoey, editor of the Canadian Medical Association Journal, who wrote last month that Health Canada and the U.S. Food and Drug Administration "failed miserably" in sounding the alarm about the serious side-effects of Vioxx, said he was surprised to learn that Health Canada lacks the necessary regulatory powers.
"There is clearly something wrong here," Dr. Hoey said yesterday. "It's curious that they have no authority to enforce post-market studies from these companies. . . . They should have it."
Without such power, Dr. Hoey pointed out, drug companies have little incentive to evaluate safety questions that come to light only when a drug reaches the real world of the market where it's taken by millions of people, many of whom are "older, sicker, and take multiple drugs," compared to those involved in early tests.
In Canada, pharmacies dispensed more than 15 million Vioxx prescriptions in the five years it was sold here.
The Globe report showed the FDA called repeatedly for a pure heart-safety study after learning of a cardiovascular risk connected to Vioxx in 2000. But the FDA, which has said it also lacks regulatory powers, did not force Merck to conduct one.
Many say an explicit cardiovascular investigation of Vioxx could have exposed the drug's safety risks sooner, allowing patients to judge for themselves, and with their doctors, whether they wanted to continue to take it.
In last week's New England Journal of Medicine, editor-in-chief Jeffrey Drazen wrote: "Had trials designed to test the question of cardiovascular toxicity directly been launched in 1999 and executed with urgency, substantial morbidity and perhaps a substantial number of deaths could have been prevented."
Dr. Bethiaume said in a recent interview that the Vioxx experience has prompted discussions within Health Canada on how to improve regulatory procedures. Federal Health Minister Ujjal Dosanjh, who has recently called for greater "transparency" at Health Canada and reforms to the drug-approval system, was unavailable for an interview yesterday.
Dr. Bethiaume agreed that if Health Canada could ask companies to conduct certain trials "it would carry some advantages."
Dr. Bethiaume also noted that drug companies do not necessarily make regulators aware of all the studies they might be conducting on a particular drug, or what safety information might have flowed from such trials.
"There is some discussion taking place [within Health Canada] about how can you make sure the drug company is sharing all the information it has on trials," he said, referring to efforts under way to register all clinical trials.
In recent weeks, for example, it has become clear other cox-2 drug makers knew more about the heart risks of their drugs than they revealed.
After the market withdrawal of Vioxx last fall, Pfizer Inc., for example, had said it had no evidence that its cox-2 painkillers Celebrex and Bextra increased heart problems.
But at last week's FDA hearing into the safety of cox-2 drugs, Pfizer was criticized by FDA panel members for not revealing that it indeed had studies that suggested its drugs were linked to heart problems.
A special FDA panel voted last week that all cox-2 drugs should carry a warning about their link to cardiovascular risks. The panel also voted for the possible return of Vioxx so long as doctors prescribed it at a low dose as a drug of last resort to patients who are warned of risks.