A new research project in British Columbia aims to develop a tool to allow drug doses for children to be tailored to their individual genetic makeup in order to help prevent potentially life-threatening drug reactions.

According to Health Canada, more than half of newly approved therapeutic health products prompt serious reactions that are discovered only after the product reaches the market. Three-quarters of medications have never been tested in children.

Dana Tent recalled how her son's hearing was damaged after he reacted to the cancer medication cisplatin.

"We were warned that this could happen," Tent said.

"We kept doing audio tests after each round of chemo, but we had no choice but to go on if we wanted to beat the cancer. When it was finally confirmed that his hearing had been permanently damaged, I almost couldn't bear it. It was just so unfair."

The $3.9 million project announced in Vancouver on Friday will focus on three drugs that can cause serious reactions in children:

• Cisplatin: The drug of choice for solid tumours in children and ovarian cancer in women. It causes hearing impairment in the vast majority of children who receive it — a million new patients per year in North America and Europe.
• Anthracycline: A very effective leukemia drug. It causes heart damage in 18 per cent of children who receive it. Nearly a million patients in North America receive this drug annually.
• Codeine: A mother's use of the drug during pregnancy can cause infant mortality. Up to 2,000 Canadian babies per year are at risk based on their genetic profiles.

Like buying shoes

Dr. Bruce Carleton, a clinical pharmacologist and director of pharmaceutical outcomes program at Children and Women's Health Centre of B.C. and Dr. Michael Hayden, a geneticist and director of the UBC Centre for Molecular Medicine and Therapeutics, will lead the project.

The project will use thousands of patient samples from pediatric teaching hospitals across the country.

The researchers hope their work will lead to diagnostic tests that doctors could use to safely select medications and drug doses tailored to a patient's genetic makeup.

Hayden likened the research to buying shoes.

"We measure the foot first and take into account that everyone has a different shoe size," said Hayden. "The same goes for drugs."

The study is funded by Genome BC and other funding partners.

Last week, Health Minister Leona Aglukkaq announced more funding to monitor the safety of drugs already on the market.