Retraining a Dyslexic Brain.

Shire Pharmaceuticals' best-selling drug for hyperactivity disorder has been pulled from the market in Canada after being linked to the deaths of 14 children and six adults.

Health Canada, the national regulator, said the decision was a result of a "thorough review" of safety data which revealed 20 cases of sudden death and 12 reports of stroke in patients taking Adderall.

The news prompted a 10% fall in Shire Pharmaceuticals' share price.

The drug contributes about half of the firm's $1.3bn (£695m) annual sales total.

Adderall is a combination of amphetamine salts used to treat people with attention deficit hyperactivity disorder.

It is sold in the United States by generic manufacturers but Shire manufactures a slow-release version named Adderall XR on which it still retains the patent.

The drug has been sold in the US for about 10 years but only for a year in Canada. In Britain, it does not have formal marketing authorisation although it is available through wholesaler BR Pharma if doctors request it.

Health Canada said the deaths were not associated with drug overdose or abuse, and that the incidents leading to death were higher in patients taking Adderall than those taking other treatments for the disease, leading it to ask Shire to withdraw the drug from sale.

The company's share price recovered some of its initial 16% fall when the news first emerged and ended down 64.5p at 577.5p.

City analysts had digested the information and reassured investors that the American regulator, the Food and Drug Administration, had seen the same information and the drug was still on sale in the US, its largest market.

The FDA said that after looking at the data and at Health Canada's analyses, it "does not feel that any immediate changes are warranted in the FDA labelling or approved use of this drug".

The American regulator had studied 12 cases of sudden death in people under 18 who were taking Adderall between 1999 and 2003.

They were all male and had an average age of 12. Last autumn it had warned doctors not to prescribe the drug to children with structural cardiac abnormalities, as five of the 12 children who died had heart abnormalities.

The FDA said some of the other cases had been complicated by other illnesses and very rigorous exercise.

It also found that the number of deaths was similar to the rate found in the population at large.

The regulator said it is conducting further analysis of the information.

Shire Pharmaceuticals said yesterday that it is confident that the drug is safe and effective and is disappointed the Canadian regulator has suspended its sale.

"Although Shire is complying with this request, the company strongly disagrees with the conclusions drawn by Health Canada and is considering appropriate responsive action," said a statement.

A spokesman said that 37 million prescriptions had been written and more than one million patients had taken the drug. Analysts at Deutsche Bank said that the Adderall drugs make up 55% of Shire Pharmaceuticals' sales and about 60% to 65% of its profits.

"We believe the immediate impact will be to remove some $10m of Canadian sales, but US growth will undoubtedly be adversely affected," the bank said in a note to clients.

Credit Suisse First Boston decreased its valuation of the company by $1bn to cover the risk of a withdrawal in the American market and the potential for litigation.

Original article February 2005.

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