Canadians who take the drug Avandia to manage their Type 2 diabetes are being warned to consult their doctors after a disturbing new study finds it may significantly boost the risk of heart-related death.
Published online Monday in the New England Journal of Medicine, the analysis pooled the results of dozens of studies and found the drug increased the risk of heart attacks by 43 per cent and increased the risk of heart death by 64 per cent.
The U.S. Food and Drug Administration did not issue a label warning on the medication in response to the study.
Both the FDA and experts say worried patients should not stop using Avandia on their own.
"We don't want patients stopping their diabetic medications...the ramifications of that are terrible and the drug is not being pulled off the market at this point," Dr. Marla Shapiro, CTV's medical specialist told Canada AM. "There's an alarm that's being put out and a discussion that should be had."
Shapiro said the methodology of the study does not follow patients forward in time, which is one of the reasons why some experts have expressed doubt.
She advised that people using the drug should consult their doctor on an individual basis.
Doctors say that it might be less risky to continue treating the diabetes with the drug than stop because of potential heart risks.
More than six million diabetic patients have used the drug Avandia worldwide for Type 2 diabetes since it was first released on the market eight years ago.
Avandia helps sensitize the body to insulin and was considered a breakthrough medication for blood-sugar control.
The drug, known generically as rosiglitazone, is sold by London-based GlaxoSmithKline PLC.
"Unfortunately, rosiglitazone appears to increase, rather than decrease, the most serious complication of diabetes -- heart disease," Dr. Steven Nissen, chairman of cardiovascular medicine at the Cleveland Clinic, said in a statement.
Nissen and colleagues at the Cleveland Clinic analyzed 42 clinical trials involving close to 28,000 patients.
Avandia is Glaxo's second-biggest product with worldwide sales estimated at $US3.2 billion last year.
The company's stock ended up down almost eight per cent on Monday in the wake of the study's release.
Glaxo protests
Glaxo's chief of diabetes drug development, Dr. Lawson McCartney, said the analysis is not definitive scientific proof.
The company is not seeing "anything like" the risks reported in the medical journal, he said during a conference call on Monday.
"We remain very confident in the safety and of course in the efficacy of Avandia as an important diabetic medicine," McCartney said.
Nissen's study uses information that became public in the wake of another drug safety case, one that led to a US$2.5 million-settlement paid by Glaxo.
Former New York Attorney General Eliot Spitzer filed a lawsuit against the company over the release of data on the safety and effectiveness of its drugs.
Spitzer, now New York governor, accused Glaxo of fraudulently withholding some results of studies that had examined the safety of prescribing the antidepressant Paxil to children.
GlaxoSmithKline argued it didn't attempt to mislead anyone, and said it has always been in favor of widespread disclosure of clinical trial results.
Drug approvals
The new analysis has raised questions about the FDA's drug approval and monitoring system.
The drug "represents a major failure of the drug-use and drug-approval processes in the United States," Drs. Bruce Psaty and Curt Furberg wrote in an accompanying editorial in the New England Journal.
When the drug was approved, evidence of its benefits was mixed, they argued.
Both have been frequent critics of the FDA, especially in the case of the heart drug Vioxx.
"This, the Vioxx story, the hormone replacement story, have all kind of pointed us in the direction that we need a systematic approach to oversight of drugs when they hit the market," said Dr. Sonia Anand of McMaster University.
Shapiro noted that studies initially looked at how well Avandia managed blood sugar levels, "which it does well, but we have to look at all the outcomes, including cardiovascular health ... so yes we need to be looking at our drug approval system and how we garner all this information."
Dr. Robert J. Meyer of the FDA's Center for Drug Evaluation and Research defended his agency, saying, "We've tried to weigh the risks of going forward with an uncertain message ... with the level of uncertainty about the safety signal before us.
With a report from CTV's Scott Laurie and files from The Associated Press
