TORONTO – When you get a drug prescription from your doctor, do you ask how long the drug has been on the market? What about which kind of review process it went through before approval? New research suggests the answers to these questions can have serious health implications.
Drugs that go through Health Canada’s priority review process are more likely to have serious safety issues compared with drugs that go through the standard review, according to a new study from York University.
The study looked at 434 drugs approved by Health Canada between 1995 and 2010. The drugs are called new active substances (NAS) which refers to drugs that have never before been marketed in any form in Canada. They range from treatments for headaches, heart disease, cancer, and more.
These new drugs go through one of two Health Canada review processes: the 300-day standard review or the 180-day fast-tracked priority review.
“Drugs reviewed under the standard and the expedited processes are reviewed under the same regulatory framework – the level of scrutiny and the rules applied remain identical,” Health Canada wrote in an email to Globalnews.ca on Oct. 9. “Highly qualified scientists conduct the health-risk assessments for drugs prior to authorization and, in all cases, the evidence must clearly show that benefits of the drug outweigh the risks.”
If the new drug offers a significant therapeutic improvement over existing drugs, or treats something for which there’s currently no treatment, prevention or diagnosis, it will go through the faster priority process.
Drug safety: priority versus standard review
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Study author and York University Faculty of Health professor Dr. Joel Lexchin looked at how many of the NAS subsequently received serious safety warnings, or had to be withdrawn from the market because of safety reasons.
A ‘serious safety warning’ could mean the drug has been associated with such side effects as abnormal heartbeats, the development of serious infections, or even the development of certain kinds of cancer, according to Lexchin. If a drug is withdrawn from the market, it means that the safety issues outweigh any benefit the drug might have provided.
The study then compared safety differences between drugs that went through the standard review versus the priority review.
“I found that drugs that went through the standard process had a 1 in 5 chance of either having a serious safety warning issued or being withdrawn from the market for being unsafe,” says Lexchin. “However, if the drug goes through the priority process, it has a greater than 1 in 3 chance of having the same outcome.”
So 19.8 per cent of drugs that went through standard reviews were later deemed unsafe, and that jumped to 34.2 per cent if the drug went through the priority review, a significant difference, says Lexchin, comparing the statistics to that of a baseball star.
“A baseball player who hits 200, which is 1 in 5, isn’t a very good player, and may get traded or sent down to the minors,” said Lexchin. “A player who hits 300 is considered a star on the team.”
Should Health Canada’s review process be changed?
Notably, Lexchin also found that the types of drugs in the priority category and the types of diseases they treated did not account for safety differences. “This indicates that the difference is likely due to the faster review missing serious safety issues,” he said.
One example Lexchin gives is a priority review drug used for treating Crohn’s disease and rheumatoid arthritis, called Remicade. It was approved Sept. 27, 2001 and received a safety warning less than one month later on Oct. 23, 2001, as it caused increased mortality and hospitalization due to worsening of congestive heart failure. He adds that this drug is still on the market.
Another example is priority review drug Exjade, which is used to treat iron overload in those undergoing treatment for thalassemia (a blood disorder). Exjade was approved on Oct. 18, 2006 and on Mar. 9, 2007 a safety warning was issued because of an increase in kidney failure.
Of course, drugs that go through the standard review process are also subject to safety warnings and withdrawal from the market.
One such example that went through the standard review is a drug that treats severe psoriasis, called Cimzia, said Lexchin. It was approved Aug. 12, 2009 and then received a safety warning only eight days later, saying it was associated with increased risk of cancer in children and young adults.
Health Canada says it is “false” that the faster review is rushing through the process at the risk of public safety.
Health Canada reviewed and amended the priority review process in 1999 to “ensure even greater transparency and to strengthen early access to life-saving medications for Canadian patients,” according to an email to Globalnews.ca on Oct. 10.
“Health Canada remains vigilant in ensuring that the balance of safety and access to new and promising therapies is maintained. As a result of priority review, potentially life-saving treatments can be made available sooner to Canadians.”
Note: This article clarifies an earlier version of this story that implied Cimzia went through the priority drug review.
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