Health Canada probes asthma drug's possible link to suicide after FDA advisory

Health Canada said Thursday it is following the FDA's lead in investigating the asthma drug Singulair's possible link to suicide, following reports of adverse reactions.

"Suspected adverse reactions have been reported," Paul Duchesne, a spokesman for Health Canada, told CBC News. "Health Canada is investigating."

He said results of the review would be released as "soon as possible."

Singulair is used to treat asthma and allergy symptoms. According to Mike Evans, a Toronto-based family physician, millions of Canadians currently take the drug.

"Singulair has made itself quite a little niche — a lot of people use it," he told CBC News Friday.

Evans said that in clinical trials of the drug involving 11,000 people, there was no evidence of suicide. However, he acknowledges that data could have been missed.

"In asthma trials, suicide rates and depression aren't something you would necessarily follow. I'm not sure we can trust the data," said Evans.

The U.S. Food and Drug Administration announced Thursday it is investigating a possible link between Merck's drug Singulair and suicide.

The FDA says it is reviewing reports of mood changes, suicidal behaviour and suicide in patients who have taken the drug, which was Merck's bestselling product last year. It anticipates the review may take up to nine months to complete.

The FDA issued an advisory that said: "Patients should not stop taking Singulair before talking to their doctor if they have questions about the new information. Health-care professionals and caregivers should monitor patients taking Singulair for suicidality (suicidal thinking and behaviour) and changes in behaviour and mood."

Evans said that if a person has had depression or suicidal thoughts and is taking the drug, they should contact their physician immediately to look for alternatives.

In the past year, Merck has updated the drug's labelling four times to include information on tremors, anxiousness, depression and suicidal behaviour reported in some patients.

Singulair had sales of $4.3 billion US last year.