While health regulators in both Canada and the U.S. wrangle over what to do about the diabetes medication Avandia, some are raising concerns about why clinical studies are still recruiting patients to test the controversial drug.
Avandia, or rosiglitazone as it's known generically, was once heavily promoted for Type 2 diabetes because it helps to lower blood-sugar levels in patients. But it has come under intense scrutiny in recent years.
Avandia's potential to raise the risk of heart attacks in some patients was brought to light in a 2007 New England Medical Journal article that reported a 43 per cent higher risk of heart attacks among Avandia patients when compared with those taking other diabetes drugs, including Actos.
Then last June, scientists working on a large study called RECORD, concluded that Avandia did increase heart failure risk in some patients, but didn't increase the risk of cardiovascular death compared with standard diabetes drugs.
The pendulum swung again last August when a Canadian study published in the British Medical Journal concluded that Avandia carried a higher risk of heart failure and death than Actos.
The Institute for Clinical Evaluative Sciences (ICES) researchers in that study concluded switching 1 million patients from Avandia to Actos would prevent 3,700 deaths and 8,300 people from going to hospital around the world.
Last month, the U.S. Food and Drug Administration issued a notice to say it was still reviewing all the studies on Avandia and was not yet ready to offer recommendations about the use of the drug. It's planning to offer its assessment of the drug's risks and benefits at a meeting in July, 2010.
But what troubles some is that patients in Canada and around the world are still being recruited for long-term studies of the risks and benefits of Avandia.
A huge study called TIDE is still recruiting patients in Canada. Dr. Hertzel Gerstein, of McMaster University in Hamilton, who is the lead Canadian investigator on thate trial, says the study is necessary research.
"The question we are asking on the trial is overall, are the benefits such that they outweigh the risks of the drug?" he explained to 麻豆影视.
"Clearly, we would not be doing studies if we knew drugs had benefits or harms. We are doing studies because we don't know the answer."
Health Canada says it continues to review all available safety information for Avandia and will take appropriate action and communicate new safety information to Canadians and healthcare professionals as necessary.
"At this time, the benefits of rosiglitazone are still considered to outweigh the risks when used as directed in the Canadian Product Monographs and following the advice contained in the public and healthcare professional communication issued on Nov. 6, 2007," the agency said in an email to 麻豆影视.
But others say there have been too many red flags raised about Avandia already to continue such studies.
"Exposing thousands of people to this drug for many years, just to see if existing studies are right, doesn't make a lot of sense," says Dr. David Juurlink, the scientist who was the lead investigator in the ICES study that compared Avandia and Actos.
"The idea that you would enroll tens of thousands of patients into a study and give them this drug for years just to see if it is really more dangerous, that to me that is something you might do to guinea pigs, not to patients," he says.
Prof. Jonathan Kimmelman, of the Biomedical Ethics Unit at McGill University in Montreal has reviewed the research so far and says he too is concerned.
"You are randomizing patients to a drug that has an unfavourable risk-benefit balance. That is not right," he said.
One group of researchers in Denmark has decided not to enroll patients in its arm of the TIDE study until the U.S. FDA drug review meeting in July.
But the studies in Canada and the U.S continue to recruit patients to learn more about the benefits and dangers of this drug.
With a report from CTV's medical specialist Avis Favaro and producer Elizabeth St. Philip
