Hay Fever Drug Probed after Link to Birth Defects

By Tom Arnold
Friday April 26, 2002

Claritin, Canada's most popular over-the-counter anti-histamine drug, is under investigation by Health Canada following European report of birth defects in children whose mothers took the drug while pregnant.

The federal department made the announcement late yesterday after the scientific committee of the European Medicines Evaluation Agency announced it was reviewing the safety of Schering-Plough Corp.'s hay fever drug across Europe, at the request of Sweden. The review began after Swedish birth registry records reviewed 15 cases of hypospadia - a malformation of the penis among 2,780 children - half were boys - whose mothers used the drug in early pregnancy.

"We have not heard of this problem before associated with Claritin, but we will investigate this, we are going to look into it," said Ryan Baker, a spokesperson for Health Canada.

Boys with the malformation have the opening of their penis on the underside instead of at the tip.

A spokesperson for the European evaluation agency said the defect could occur naturally but the number of cases reported in Sweden was about three times higher than expected.

However, Dr. Gideon Koren, director of Motherisk, a counseling service for women on the safety of drugs during pregnancy and breastfeeding at they Hospital for Sick Children in Toronto, said hypospadia is a very common malformation.

"It is not the first time hypospadia has been brought up as a culprit. It happened with the oral contraceptive pill for example, later on to be found not to be at risk," Dr. Koren said.

"We are also conducting several studies on drugs and I am not aware of any trend similar to this. I do not believe that this class of drugs will end up being problematic.

"A lot of signals have been coming from Europe which in the end do not end up being the real thing, often times raising a lot of anxiety among women," he added. "No one should interpret this notice as a reason for panic."

In 2001, drug sales for all forms of Claritin totalled $40-million, according to IMS Health, a market research firm that tracks drug sales. It is ranked No.1 among anti-histamines, capturing just over 45% of the market n Canada.

Worldwide sales of the hay fever remedy were worth nearly $3.2-billion in 2001, making it the company's most important product.

The Canadian probe will get underway immediately, said Mr. Baker. "We will look at any adverse drug reaction reports we have received on these drugs and it could involve contacting the European Medicines Evaluation Agency," he said.

The European evaluation agency has been compiling data on adverse events associated with the use of Claritin. Canada keeps tabs through the Canadian Adverse Drug Reaction Monitoring Program, but it was not clear yesterday whether specific data have been compiled on the popular medicine.

Schering Canada Inc. could not be reached for comment late yesterday.

However, in a statement in Europe, Schering-Plough said concerns about the drug were based on a "flawed methodology and analysis" by Sweden's drug regulatory agency and "has the potential to cause undue alarm to women worldwide."

"We have not been able to corroborate this finding in the Swedish birth registry with any other registry worldwide," said Dr. Robert Spiegel, the company's chief medical officer. "We are confident that these cases constitute random events.

"In some reports in the United States, the rate can be as high as 8 per 1,000 births," he added. "So the range of what you expect by chance."

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