Fourteen deaths occurred in children and six deaths in adults. These deaths were not associated with overdose, misuse or abuse.

The FDA notes in a statement that although Health Canada decided to suspend sales, it did not revoke approval of the drug as a treatment for attention deficit and hyperactivity disorder (ADHD).

After consulting with the Canadian authorities regarding their analyses of adverse event reports, and based on FDA's own knowledge and assessment of the reports, the U.S. agency says it felt that no immediate changes were warranted in its labeling or approved use of Adderall and Adderall XR.

Patients using the drug (or parents of children taking it) who have questions should consult their physicians before making any alterations to their therapy, FDA advises.

14 Deaths, 2 Strokes in Children

Health Canada says that it instructed Shire BioChem Inc., the manufacturer of Adderall XR, to withdraw the drug from the Canadian market. Health Canada is advising patients who currently are being treated with Adderall XR to consult their physician immediately about use of the drug and selecting treatment alternatives.

Health Canada's decision came after a thorough review of safety information provided by the manufacturer, which indicated there were 20 international reports of sudden death in patients taking either Adderall (sold in the United States, not in Canada) or Adderall XR (sold in Canada).

These deaths were not associated with overdose, misuse or abuse. Fourteen deaths occurred in children and six deaths in adults. There were 12 reports of stroke, two of which occurred in children. None of the reported deaths or strokes occurred in Canada.

Thorough Review of Drug Class Requested

A preliminary review of safety data for the other related stimulants authorized for use in the treatment of ADHD in Canada has been conducted. In that review, the incidence of serious adverse reactions leading to death was higher in Adderall and Adderall XR combined than in the other drugs of this class.

Health Canada has asked manufacturers of other related stimulants approved for the treatment of ADHD to provide a thorough review of their worldwide safety data. Information updates will be provided by Health Canada as they become available.

Patients taking drugs of the same class for the management of ADHD should NOT discontinue their medication, and should consult with their physician if they have any concerns or questions, Health Canada advises.

Manufacturer 'Strongly Disagrees'

Shire is complying with Health Canada's request but says it strongly disagrees with the conclusions drawn by the Canada authority and is considering appropriate responsive action.

"We are surprised by this action from Health Canada. Shire remains confident in the safety and efficacy of Adderall XR," says Shire CEO Matthew Emmens.

Shire stock fell sharply in heavy trading Thursday following the announcement of the Canadian government's decision.