The US Food and Drug Administration should delay changing the warning label on products used to treat attention deficit hyperactivity disorder based on the stimulant drug methylphenidate to highlight possible psychiatric and cardiovascular side effects until there is a good sense of class effect, an advisory panel yesterday concluded.

Earlier this week, the agency said it was considering changing the label on the products, which include Johnson & Johnson’s Concerta, after post-marketing surveillance data suggested the possible side effects [[30/06/05a]]. The FDA received 36 reports of psychiatric events in children taking Concerta over a one-year period, and 16 reports for other methylphenidate products.

However, the advisory panel said that the side effects were not new or significant, and committee members were hesitant to recommend a labeling change without an analysis of other ADHD therapies, such as amphetamine products and Eli Lilly’s non-stimulant offering, Strattera (atomoxetine). They cautioned that such warnings could be “interpreted as causality,” potentially driving patients to other ADHD drugs with potentially worse psychiatric effects.

Albeit the committee members felt that the FDA should communicate something to the public about the potential for emergence of psychiatric side effects, such as suicidality and hallucinations. “The train is out of the station,” committee member Judith O’Fallon of the Mayo Clinic said, noting the media exposure the matter has received in recent days.

The FDA is now considering several trials to assess the CV risk associated with ADHD drugs, which was thrown into the spotlight earlier this year with the Canadian market suspension of Shire Pharmaceuticals’ Adderall XR (extended-release amphetamine) [[10/02/05a]].