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Be wary when using newly released drugs

Study finds quarter of medications pulled from market or needed safety warning

Almost a quarter of prescription medications approved for patients in Canada over a 16-year period went on to be pulled from the market or to require a strongly worded safety warning to patients, a new study says.

In a Research Letter published online in the Archives of Internal Medicine, University of Toronto researcher Dr. Joel Lexchin looked at the 434 drug approvals that moved through Health Canada's drug-safety arm from the start of 1995 to the end of 2010. Canada's drug-safety agency operates much like the U.S. Food and Drug Administration, so the study may reflect the state of drug safety in the United States as well.

About a quarter of the drugs approved in that period received a "priority review" - essentially, a fast-track deliberation. But when Canada's drug-safety agency approved a medication after such a review, the likelihood that the agency would have to take later safety action was about 50 per cent higher than when a medication was subject to the customary deliberation period.

And more than seven in 10 of those fast-tracked approvals were for drugs that did not even represent a "major therapeutic advance" over medications already available. When the patient population is sufficiently large or growing, drug-makers sometimes elbow their way into a profitable market by seeking expedited approval for "me-too" drugs; their drug candidates tend to mimic the effects of medications already available, but do so in subtly different ways.

Compared to medications that got full safety reviews, these fast-tracked me-too drugs had a rate of safety problems that was even more elevated.

But some drug candidates get a fast-track review because they meet an unmet need in the treatment of a serious illness.

Lexchin's analysis found that priority review medications used to treat important clinical conditions such as cancer and HIV/AIDs were no more likely to require later safety actions than the fast-tracked me-too drugs.