A drug used to treat attention deficit and hyperactivity disorder has been linked to a dozen strokes and 20 deaths and was withdrawn from drugstores in Canada Thursday. U.S. officials notified doctors of Canada's action but did not restrict sales here.
The unexplained deaths linked to the drug, Adderall, occurred in the United States between 1999 and 2003, a spokesman for Shire Pharmaceuticals, the drug's maker, said Thursday.
Fourteen of those who died were children, as were two of those who had strokes, said officials for Health Canada, a Canadian health care agency.
Health Canada Thursday removed Adderall XR, the extended release capsule version of the drug, from drugstore shelves. That is the only form of the drug sold in Canada.
"We have suspended sale because of the albeit rare but catastrophic event that has been reported," Dr. Robert Peterson, director general of Health Canada's Therapeutic Products Directorate, said at an Ottawa news conference.
Health Canada is asking manufacturers of related stimulants to review their safety record. The U.S. Food and Drug Administration's reporting system logged seven sudden deaths of children taking those drugs - Concerta and Ritalin - over the same period.
The FDA issued an alert notifying health care professionals about the Canadian action: "At this time, FDA cannot conclude that recommended doses of Adderall can cause SUD (sudden unexplained death), but it is continuing to carefully evaluate these data."
Last August, Shire, in conjunction with an FDA review, changed its U.S. label for Adderall to include a warning about sudden deaths in children with structural cardiac abnormalities.
Matthew Cabrey, a Shire spokesman, said, "Shire does not agree with the conclusions of Health Canada. Shire maintains our confidence in the safety and efficacy of Adderall XR."
Cabrey said Health Canada learned about the deaths in November, when Shire sought to add a warning label there.
Adderall comes in tablets and extended-release capsules; the deaths occurred in people who took either version. In the United States, 700,000 prescriptions have been written for Adderall XR and 300,000 for Adderall tablets, Cabrey said.
Dr. Robert Temple, associate director for medical policy in the FDA's drug center, said, "We did not reach the conclusion that there was evidence of risk in people without structural cardiac abnormalities."
Temple said some of the cases had complicating factors: For example, one child who died had heat exhaustion and was exercising at a camp in 100-degree heat.
At The Johns Hopkins Hospital in Baltimore, Dr. John Walkup, a child and adolescent psychiatrist, prescribes Adderall and Ritalin.
He urged caution in prescribing Adderall: "If you have a kid who has a structural cardiac problem, the doctor should be very careful."