Drugs that are fast-tracked through Health Canada's accelerated approval process may be putting Canadians at risk, new research shows.

Fast-tracked drugs are more likely to have serious safety warnings added later or be pulled from shelves for safety reasons, a York University study has found.

The researchers followed 434 new active substances (NASs) approved by Health Canada between 1995 and 2010.

Those that went through Health Canada's standard 300-day review had a one in five chance of having a warning added after their debut on the market or being recalled, compared to one in three for drugs funnelled through the 180-day priority process.

Pharmaceutical companies have the option to request the priority process for a new drug. Health Canada decides whether to fast-track a drug based on its benefits-to-risks ratio. It tends to grant the priority process to drugs that have major therapeutic advances for serious illnesses like cancer and HIV.

But the type of drug and the seriousness of the illness it treats had no bearing on whether it was later recalled or labelled with a serious safety warning, the York study found.

"Even drugs that provided no major therapeutic advances were still more likely to acquire serious safety issues if they were put through the priority review," lead author Dr. Joel Lexchin said in a press release.

"This indicates that the difference is likely due to the faster review missing serious safety issues."

The study was published in the Archives of Internal Medicine.

QMI Agency has contacted Health Canada for comment.