TORONTO — Canada has followed in the footsteps of the United States and Britain, instructing doctors and parents that children under 18 shouldn't take a popular anti-depressant because it appears to trigger suicidal thoughts in some adolescent users.

GlaxoSmithKline, the makers of Paxil, admitted in a statement Tuesday that studies it conducted showed the drug also didn't appear to work in children who were taking it.

"First of all, it didn't show that it was effective for treating the depression in children and adolescents and then secondly there were these adverse events that were detected," said Dr. Anne Phillips, vice-president for research and development and chief medical officer for GlaxoSmithKline.

Those adverse affects ranged from mood fluctuations and increased crying to suicidal thoughts and suicide attempts, Phillips said.

A prominent British psychiatrist who has warned for years that the class of drugs to which Paxil belongs can trigger suicide in some users said the move to block the use of the drug in children should have happened earlier.

"Oh yes, (it's) way overdue," said Dr. David Healy in a telephone interview.

Healy said Health Canada should follow suit with other drugs in the popular class of anti-depressants known as SSRIs - short for selective serotonin reuptake inhibitors.

A spokeswoman for Health Canada could not say if decisions to block use of other SSRIs among children were in the works. Krista Apse said she did not know if the department was reviewing the safety record of all SSRIs in children.

But Phillips said she believes other such reviews will take place.

"It's our understanding that Health Canada will be looking at other products in similar class and classes," she said.

GlaxoSmithKline stressed that children currently taking Paxil must not discontinue its use abruptly. Discontinuing the medication should be done under a doctor's care, the company said, with a gradual reduction of dose recommended to minimize "discontinuation symptoms."

Phillips would only give sketchy information on the trials GlaxoSmithKline had conducted, saying she didn't know exactly how many there were, where they were conducted or why specifically they were undertaken.

"We were studying the use of the product in children and looked at the ongoing trials," she said. "When we put the trials together and looked at the safety data, that's when we noticed that there may be something there.

"Health Canada (then) decided that really this product should not be used in children and adolescents under the age of 18."

Drug regulators in the United States and Britain had already come to the same conclusion, saying last month that Paxil was not safe for those under 18.

The drug, which is marketed as a treatment for depression and anxiety in adults, had not been approved for use in children. But so called "off licence" use of drugs is not uncommon.

Neither Health Canada nor GlaxoSmithKline could estimate how many children in Canada might be taking the drug.
"We don't track that information," Apse said.

Healy estimated thousands of children in Canada may be on Paxil or another SSRI. It's estimated that between 8,000 to 10,000 children in Britain were on the drug, he said, adding use of anti-depressants in children is more common in Canada and the United States than it is in the United Kingdom.

He said GlaxoSmithKline had conducted about nine trials in children, though only one was published. The trials looked at whether the drug was effective and safe in the treatment of several problems: depression, social phobias and obsessive compulsive disorder.

When the data from the trials was submitted to the British regulatory agency, "they concluded that actually there's a real risk of children going on these drugs and becoming suicidal. And it's a real risk for children particularly who are depressed," he said.

According to published reports from the United States, the data - which were later submitted to the U.S. Food and Drug Administration - showed the risk of suicidal thoughts and suicide attempts was three times greater among adolescents taking Paxil than among those receiving placebos.

The company's statement only said that the rate of adverse affects was higher and that there were no suicides in the pediatric trial program, which saw more than 1,000 patients receive the medication.