The Health Council of Canada is calling for better monitoring of prescription drugs after they are on the market. (iStock)

The Health Council of Canada is calling for changes in how prescription drugs are monitored for safety and effectiveness.

In a discussion paper released Wednesday, the council says the number of people exposed to unsafe drugs has increased over the past 25 years.

Two drugs that were heavily promoted and widely prescribed in Canada in 2000 — Baycol and Vioxx — were withdrawn because of safety issues, the council indicates. Between 1999 and 2004, when Vioxx was removed from the market, about 16 million prescriptions for the drug had been written.

The council, which is funded by Health Canada, argues that Canadians aren't aware of the safety concerns of drugs now on the market.

"People often think that since a drug has been approved by Health Canada, it is safe," said John G. Abbott, the Health Council of Canada CEO.

"What Canadians don't know about are the limitations in our current pre-market testing and the lack of surveillance once a drug has entered the market."

Limited scope

Pre-market testing is completed by pharmaceutical companies in a short period of time with a relatively small number of patients, the paper says. Although mandatory, pre-market testing is limited in scope.

The paper goes on to argue the current random nature of post-market surveillance is because of the lack of regulatory requirements that compel drug companies to conduct additional research on product safety and effectiveness once their drug has entered the market.

Joel Lexchin, a professor at York University's school of health policy and management and one of the lead authors of the paper, said Health Canada has "limited authority" to deal with safety issues of drugs on the market.

"Health Canada cannot require companies to conduct post-market studies or change drug labels after the product has been approved unless significant new safety issues have been identified," Lexchin said.

"And although it has the authority to order drugs to be withdrawn from the market, they rarely exercise this power."

The council recommends, among other things, that:

• Post-market research required by Health Canada be registered, unbiased, transparent, free from conflicts of interest and follow guidelines.
• Legislative authority be given to Health Canada to impose penalties for failure to complete post-market safety studies.
• All required post-market studies be made public.
• All researchers and committee members submit conflict-of-interest disclosures