A federal health official said Thursday that there was a strong possibility that popular drugs like Ritalin used to treat attention deficit hyperactivity disorder may be linked to the deaths of 25 people.
"There's smoke. Does that represent a fire?" asked Dr. David Graham of the Food and Drug Administration.
To find out, an FDA advisory committee considered how best to study whether the popular drugs increased the risk of death and serious injury.
"We wouldn't be going through this exercise if we didn't think there was a real possibility of increased risk," Graham told reporters.
Further studies would examine the incidence of sudden death and serious health problems, including stroke and heart attack, among some of the millions of children and adults treated each year with the drugs. That could lead to new warning labels.
The deaths occurred between 1999 and 2003, according to an FDA report. Nineteen of them involved children. The report also detailed 54 cases of serious cardiovascular problems, including heart attack, stroke, hypertension, palpitations and arrhythmia, in adults and children being treated with ADHD drugs.
Some of these ADHD drug-treated patients had pre-existing heart conditions or hypertension.
The drugs include amphetamines, such as Adderall, and methylphenidates, sold as Ritalin, Concerta, Methylin and Metadate.
The FDA said it has tallied an additional 26 deaths between 1969 and 2003 in ADHD patients involving death by suicide, intentional overdose, drowning, heat stroke and from underlying disease.
The FDA's Drug Safety and Risk Management advisory committee is reviewing different ways to study whether the deaths are linked to use of the drugs. The few studies that have looked at longer-term use of ADHD drugs provide little information on those risks, the FDA said.
Analysis of the reports of death and injury suggests a possible link between the drugs and cardiovascular problems, the FDA's Dr. Kate Gelperin told the panel. But the link is not conclusive, nor is it clear whether there is an increased incidence of death or serious injury among people treated with the drugs, she added.
That, Gelperin said, "is really a question we'd like to have answered."
An FDA review found fewer than one case of death or serious injury per 1 million ADHD drug prescriptions filled, with one exception: 1.79 cases per million of nonfatal cardiovascular or cerebrovascular problems in adults treated with amphetamines.
Currently, about two million children and one million adults are prescribed ADHD drugs each month, the FDA's Dr. Andrew Mosholder said. Adult use alone grew 90 percent between March 2002 and June 2005, he said.
Sales of ADHD drugs increased to $3.1 billion in 2004, from $759 million in 2000, according to IMS Health, a pharmaceutical information and consulting firm.
That stepped up use could spell increased risk.
"Because adults have a higher risk of heart disease and stroke to begin with, any increase in risk caused by these drugs could affect a large number of people," Graham said.
The FDA's Canadian equivalent, Health Canada, briefly pulled the ADHD drug Adderall XR from the market last year. A Canadian panel eventually concluded there was inadequate evidence of increased harm from the drug. The FDA reached a similar conclusion at the time.
Adderall is made by Shire Pharmaceuticals and Ritalin is made by Novartis Pharmaceuticals Corp. Various other companies make generic versions of Ritalin as well.
Sen. Chuck Grassley, R-Iowa, criticized the FDA's pace in studying the issue earlier this week.