Deadly side-effects earn ADHD drugs warning

''The effects are usually mild or moderate, but in some patients, this stimulation may - in rare cases - result in cardiac arrests, strokes or sudden death,'' Health Canada warns.

The agency has strengthened the safety labels and prescribing information for Adderall XR, Concerta, Dexedrine, Ritalin and Ritalin SR and Strattera, as well as Attenade and Biphentin, two drugs that have been approved but are not yet available in Canada.

More than 1.9 million prescriptions for the stimulants were filled by Canadian retail drugstores in the 12 months ending April 30, 2006, according to health research firm IMS Health. An estimated three million U.S. children, and 1.5 million adults, are on psycho-stimulants.

American drug regulators are considering adding a ''black box'' - the most serious warning it can issue - to ADHD drugs, warning of rare heart-related risks. There have been 25 reports in the U.S. of children and adults who died suddenly between 1999 and 2003 after taking one of the drugs, including a 13-year-old boy who died within one hour of receiving his first dose. An autopsy revealed he had a genetic heart disorder.

No deaths have been reported in Canada.

''The warning has gone out because of a theoretical increased risk of these events happening,'' says Dr. Supriya Sharma, associate director-general of Health Canada's therapeutic products directorate. The risks of cardiac arrests, strokes or sudden death occur in less than one in 10,000 patients, she says.

In a "Dear health care professional" letter issued Friday, doctors are being advised to start the drugs at the lowest possible dose and to increase it slowly. ''It's, 'start low, go slow,''' Sharma says.

Before starting the drugs, patients should tell their doctor if they are involved in strenuous exercise or activities, are using other drugs for ADHD or have a family history of sudden cardiac death.

No one should stop taking their medication without first speaking with a doctor, Sharma says.

''These drugs also give benefit to people as well. We don't want people to be going unnecessarily off the medications if there are benefits.

''(These are) still very rare side effects, this is a precautionary measureE.we don't want people to be panicking.''
ADHD is one of the most commonly diagnosed neurological disorders in school-aged children.

Dr. Atilla Turgay, a psychiatrist and chief of medical staff at Ontario's Scarborough Hospital, said the new warnings are appropriate. But he worries they could make parents more hesitant to use the drugs.

''There would be many patients whose education, social life and quality of family life would be so much disturbed if they are not on medication.

''I remember two cases where the parents were about to give the child up to the local Children's Aid Society because of unmanageable behaviour.'' Untreated ADHD can lead to aggressive behaviour and drug abuse later in life.

''We really have to judge very carefully the risk of not treating ADHD," Turgay says.

But Dr. Steven Nissen, of the Cleveland Clinic, says the warnings about serious cardiovascular risks with ADHD drugs ''might slow the exponential growth in the use of amphetamines and similar stimulants," which he says has reached "epidemic proportions."

Writing in this week's New England Journal of Medicine, Nissen says nearly 10 per cent of pre-adolescent boys in the U.S. are taking the drugs.
skirkey@canwest.com
© CanWest News Service 2006

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