WASHINGTON -- GlaxoSmithKline PLC and Shire PLC said they strengthened warnings that their attention-deficit drugs may cause psychological side effects and misuse may lead to sudden death from heart attacks and strokes.
Glaxo, the world's second-largest drug maker, said yesterday that it added the warnings to prescribing information on its Dexedrine treatment last month. Shire said it also added the warnings for its Adderall XR, the top-selling treatment for attention deficit hyperactivity disorder.
The Food and Drug Administration in May asked makers of similar drugs, called central nervous system stimulants, to add the warnings based on recommendations from two advisory committees, said Glaxo spokeswoman Holly Russell. Other products covered by the warnings would include those containing methylphenidate, used for more than 50 years, such as Novartis AG's Ritalin and generic copies.
``It's a very strong warning," said Steven Nissen, the president of the American College of Cardiology and chairman of cardiology at the Cleveland Clinic, who served on a February advisory committee that recommended the warning, in a telephone interview. ``It's appropriately worded. It basically lets physicians and patients know that these drugs do have serious cardiovascular side effects."
The warnings list side effects including suppression of growth, psychosis, bipolar illness, aggression and ``serious" cardiovascular side effects. The FDA posted a Glaxo letter to doctors and the revised prescribing information on its website yesterday. The letter doesn't name other firms.
The February advisory panel urged the FDA to require its strictest form of warning, highlighted in boldface type and outlined with a black box, to all ADHD drugs because of the risk of heart attack, stroke, and sudden death. In March a separate committee recommended additional warnings of the psychological side effects.
Basingstoke, U.K.-based Shire changed its labeling after the FDA approved the warnings July 31, spokesman Matthew Cabrey in Wayne, Pa., said in an interview.
Doctors wrote 195,000 prescriptions last year for London-based Glaxo's Dexedrine, accounting for less than 1 percent of all prescriptions for ADHD, spokeswoman Russell said in a telephone interview. Dexedrine has been available since before 1950 and generic versions became available in 2002, Russell said.
Novartis spokeswoman Gina Moran in East Hanover, N.J., wasn't immediately available to comment.