Updated

Federal regulators said Thursday that they would likely hold off on issuing new safety warnings for Concerta, a drug used to treat attention deficit hyperactivity disorder. Officials said moving too quickly could unnecessarily alarm the public about potential side effects.

FDA officials are considering altering the drug's label to more clearly alert doctors as well as parents of children with ADHD about potential medication-related side effects including visual hallucinations, psychotic episodes, and aggressive or violent behavior.

The agency has also said it intends to add new warnings that the drug may be related to the emergence of suicidal thoughts in children and adolescents who take it.

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Making Parents Aware

But officials said Thursday that they are unlikely to move ahead with the label changes until the agency collects information on similar side effects in the wider class of stimulant drugs used to treat ADHD. The review is likely to be completed in early 2006, officials said.

At the same time, regulators -- who have pledged new openness about drug safety concerns -- say they want parents of millions of children who take the popular medications to be aware of potential side effects.

"We want to try to make it clearer what the situation is with the potential adverse events," says Dianne Murphy, MD, director of the FDA's office of pediatric therapeutics.

About 1 million American children between 6 and 17 take Concerta, sold by McNeil Consumer & Specialty Pharmaceuticals. Millions more take similar stimulant drugs including Ritalin and Adderall. McNeil and Ritalin's manufacturer Novartis are WebMD sponsors.

Strattera, another ADHD drug, is not a stimulant. Strattera's maker, Eli Lilly, is also a WebMD sponsor.

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Side Effect Reports

The agency received 135 reports of side effects in children taking Concerta between late 2003 and early 2005. Thirty-six of the reports detailed psychiatric disturbances including psychosis, hallucinations, and anxiety. Eleven of the reports involved suicidal thoughts or a suicide attempt in patients taking the drug.

Researchers are not yet sure whether Concerta was the cause of the 36 reports, even though many of them occurred in close connection with the drug. Many patients who have ADHD also have other -- sometimes silent -- illnesses that can cause anxiety or psychotic episodes.

Several members of an FDA advisory committee on Thursday urged the agency to avoid label changes until the completion of a legally mandated review of the entire class of ADHD stimulants used by pediatric patients.

Experts Question Link

"It seems, at least at this point, to be quite premature because a link has not been established," says Benedetto Vitiello, MD, chief of child and adolescent treatment at the National Institute of Mental Health and a member of the FDA's Pediatric Advisory Committee.

"Nothing I've heard today about these medications makes me particularly concerned," says Thomas B. Newman, MD, a panel member and professor of biostatistics at the University of California, San Francisco.

Concerta's label already warns that the drug can cause aggression, anxiety, and agitation. The drug should not be used in patients with anxiety, and the label also warns that it may worsen psychotic symptoms in patients with psychotic disorders, such as schizophrenia.

The label does not warn about the potential for suicidal thoughts or attempts.

Clearer Labels

But officials say they're also concerned that labels for Concerta and other drugs may not be clear enough for parents and general physicians to fully understand. The labels now contain several "terms of art" used by psychiatrists that might not catch the attention of parents and primary care physicians, says Paul Andreason, MD, chief of the FDA's division of neuropharmacologic drug products.

"We're not seeing anything that we consider particularly new, but we want to be able to communicate [side effects] better," he says.

The agency is also considering 20 reports of serious heart side effects, some of which are not discussed in the labeling of Concerta and other drugs. Four cases of breathing difficulty, two cases of abnormal heart rhythms, and a case of abnormal heart enlargement were all reported to the agency but are not reflected in the drug's warnings, the agency said.

Patrick Ciccone, McNeil's vice president for medical affairs, told panelists that Concerta has helped "millions of children" and that the company is committed to providing patients and prescribing physicians with comprehensive information about our products."

Drug Safety in the Twilight Zone

The FDA's deliberations over ADHD drugs come during a time of increased public scrutiny of how it monitors drug safety and shares the information with the public. The agency was stung last year after reports that it prevented employees from sharing findings including suicidal side effects of antidepressant medications and potential heart risks with Cox-2 painkillers like Vioxx.

The episodes lead to ongoing calls on Capitol Hill for FDA reform as well as pledges for more transparency from within the agency.

Officials acknowledged Thursday that new policies urging much more rapid sharing of data with the public had left them conflicted on how to proceed regarding potential safety concerns with Concerta and other drugs. In the past, such concerns were usually negotiated in private with drug companies.

"I think the agency is struggling with how to deal with this twilight zone, where we have this concern but we may not be able to articulate it," says Anne E. Trontell, MD, deputy director of the FDA office of drug safety.

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By Todd Zwillich, reviewed by Michael W. Smith, MD

SOURCES: Dianne Murphy, MD, director, FDA's office of pediatric therapeutics. Benedetto Vitiello, MD, chief of child and adolescent treatment, National Institute of Mental Health. Thomas B. Newman, MD, professor of biostatistics, University of California, San Francisco. Paul Andreason, MD director, FDA division of neuropharmacologic drug products. Patrick Ciccone, vice president for medical affairs, McNeil Consumer & Specialty Pharmaceuticals. Anne E. Trontell, MD, deputy director, FDA office of drug safety.