Certain drugs used to treat attention-deficit hyperactivity disorder should carry a black-box warning that they may be linked to a higher risk of sudden death from cardiovascular side effects, a US Food and Drug Administration advisory panel said yesterday.

Following an analysis of side effects and patients deaths related to use of the stimulant class of ADHD drugs, the panel voted 8 to 7, with one abstention, for the strongest warning be added to the labelling of such therapies, which include Shire’s Adderall (mixed amphetamine salts), Novarits’ Ritalin (methylphenidate); and Johnson & Johnson’s Concerta (methylphenidate), among others.

The FDA is not bound by the recommendations of its advisory committee, but usually follows its decision. However, in this case, slapping a black-box warning on these products would mark an unprecedented move as the data is far from conclusive. Although higher rates of serious cardiovascular events and sudden death were found for amphetamine than methylphenidate in both children and adults, many feel that more studies are needed to confirm the extent of this relationship.

At a press conference following the meeting, Office of Medical Policy Director Robert Temple conceded that the FDA does not usually require black-box warnings for side effect data for which there is not established causality. “We don’t usually write a black box for something there isn’t pretty good evidence for,” he noted, but added that the agency would take a close look at the individual committee members’ recommendations in its deliberations.

In response to the panel’s recommendations, UK group Shire said in a statement: “While we fully support full disclosure and adequate warning, Shire believes that the interests of physicians and patients would be better served by further study to determine whether there is, in fact, a relationship between these medicines and cardiovascular events. Obtaining this information is crucial prior to taking what would be an unprecedented action to include something in a black box that is not been supported by sufficient data.”

The company also stressed that the benefits of these treatments should not be overlooked, and that stimulant medicines have been used effectively for over 50 years to treat the ADHD. And reaffirming its confidence in Adderall’s safety and efficacy, Shire pointed out that the extended-release version, Adderall XR, has been prescribed to over 1 million people since its introduction in 2001.