ADHD latest drugs to be hit by safety warnings

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ADHD latest drugs to be hit by safety warnings

Thursday , February 17, 2005

Attention deficit hyperactivity disorder (ADHD) treatments are the latest

class of drugs to be hit by safety warnings, with regulators in the UK,

Canada and US all taking action.

Canada's regulator Health Canada has instructed Shire to withdraw its drug

Adderall XR from the market following reports of sudden deaths,

heart-related deaths, and strokes in children and adults taking the

recommended doses of Adderall and Adderall XR.

The decision was based on data produced by Shire for the regulator's safety

review.

Many ADHD treatments use methylphenidate as their active ingredient but

Adderall differs in using a combination of amphetamines.

The Canadian authorities say the same adverse reactions have not been

detected in other products, but further data has now been requested from the

manufacturers.

Health Canada has only suspended Adderall XR's marketing authorisation, but

the regulator looks unlikely to allow the product to return to the market,

with the data showing the two formulations of the drug were responsible for

more fatal adverse reactions than any other ADHD treatment.

Despite the withdrawal, across the border, the US regulator has not followed

suit. The FDA's earlier interpretation of the data led to a label change

indicating children or adults with structural cardiac abnormalities should

not use the drug.

Emmens, Shire's chief executive officer, said: " We are surprised by

this action from Health Canada. Shire remains confident in the safety and

efficacy of Adderall XR. "

Adderall XR was launched in Canada at the beginning of 2004, and contributed

$10 million to the company's revenues in this time. The company depended on

the drug to generate 43% of its revenue or $535 million in 2003, and a

withdrawal in the US or other global markets would be a massive blow.

Meanwhile, in the UK, another new ADHD product, Lilly's Strattera is also

the subject of serious but rare side-effects.

A total of 67 adverse reaction reports have been made through the UK's

Yellow Card Scheme, including three reports of hepatic disorders, from an

overall number of 10,000 patients who have been prescribed the drug.

The MHRA warned health professionals that new evidence suggests it can cause

hepatic disorders including severe acute hepatitis, but that the incidence

is less than 1 in 50,000 patients.

Prescribers are advised that the reactions have not formed an identifiable

pattern, and has ruled therefore that routine liver function monitoring is

unlikely to help and is not recommended. It advises that the drug should be

discontinued in patients with jaundice or laboratory evidence of hepatic

injury, and should not be restarted.

Prof Gordon Duff, chairman of the Committee on Safety of Medicines said:

" This is an important drug in the treatment of ADHD in children, and it has

been widely and effectively used in the US and increasingly in the UK. It is

therefore important that we take a balanced approach to this new advice.

Parents should not be dissuaded from having their children treated with this

medicine, but it is right that they should be aware of possible, but rare

side-effects. "

An estimated 2.3 million patients have taken Strattera worldwide, with 41

reports of hepatic disorders recorded including two cases of severe acute

hepatitis.

Methylphenidate products are also recognised to cause liver problems in a

few rare cases and already carry the appropriate warnings.

Finally, in the US, the most important market for the drugs, Alliant

Pharmaceuticals was forced to recall a batch of its Methylin chewable

tablets after a manufacturing error resulted in three times the correct dose

going into the medication.

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