Canadian regulators ordered a drug for attention deficit hyperactivity disorder (search) pulled off the market because of reports that it has been linked to 20 sudden deaths and a dozen strokes, including some among children.

Health Canada (search) said late Wednesday that it is asking makers of related stimulants used to treat the commonly diagnosed condition to provide a thorough review of their worldwide safety data.

None of the deaths or strokes associated with Adderall XR (search), made by Basingstoke, England-based Shire Pharmaceuticals Group PLC (SHPGY), were reported in Canada, department spokesman Ryan Baker said.

"However, Health Canada has received eight reports of adverse reactions ranging in severity from convulsions to minor skin rash," Baker said. "It's not been determined yet whether these reactions were a result of Adderall XR use."

Of the 20 cases of sudden death linked to the drug, 14 were in children. Two of the 12 strokes were suffered by children taking the drug.

The adverse reactions were not associated with overdose, misuse or abuse of the drug, the department said.

Shire shares fell 10.5 percent to 574.5 pence in trading on the London Stock Exchange.

The drug is sold in Canada and the United States. A related immediate-release form of the drug, sold simply as Adderall (search), is sold in the United States but has not been approved for sale in Canada, where 11,000 patients are prescribed Adderall XR. Canadian officials approved that drug in January 2004.

Shire's chief executive, Matthew Emmens, said in a statement late Wednesday that the company "remains confident in the safety and efficacy" of the drug.

The U.S. Food and Drug Administration said it had evaluated the same reports as Canadian regulators and doesn't believe the data warranted such action in the United States.

Emmens said the FDA reviewed the same data as Health Canada last year and sought an additional warning in September that the drug should not be prescribed for people with "structural cardiovascular abnormalities."

About 700,000 people take Adderall XR in the United States, with about 300,000 more using Adderall, Shire spokesman Matthew Cabrey said. Shire reported $140 million in U.S. sales of the drugs in the third quarter of 2004.

In a statement posted on its Web site late Wednesday, the FDA said it "does not feel that any immediate changes are warranted in the FDA labeling or approved use of this drug based upon its preliminary understanding of Health Canada's analyses of adverse event reports and FDA's own knowledge and assessment of the reports received by the agency."