(Recasts, adds company comment, updates shares)
By Susan Heavey
WASHINGTON, July 7 (Reuters) - U.S. Food and Drug Administration officials are pushing for a "black box" warning about the risk of suicidal thoughts and behavior with epilepsy drugs, just days ahead of a public meeting on the issue.
"We are going to ask for a boxed warning on these drugs," FDA spokeswoman Sandy Walsh said on Monday. The warning would apply to all epilepsy drugs, even those that showed no risk signal, according to an agency memo that was also released.
The FDA will ask an advisory panel on Thursday to weigh the proposed boxed warning -- the strongest type the agency can seek. The panel of outside experts is set to discuss risks with drugs to treat the disease, which is marked by seizures that can cause involuntary movement or behavior.
GlaxoSmithKline Plc's Lamictal (GSK.L) (GSK.N) and Pfizer Inc's (PFE.N) Lyrica are among the top-selling epilepsy drugs. Others include Johnson & Johnson's (JNJ.N) Topamax and Abbott Laboratories Inc's (ABT.N) Depakote.
Shares of GlaxoSmithKline closed down 2 percent to $45.83 and Pfizer shares closed also fell 2 percent to $17.39, both on the New York Stock Exchange. Their losses exceeded a 1.4 percent decline in the Amex pharmaceutical index .DRG.
Some epilepsy drugs, which are given to prevent seizures, bring in billions of dollars a year. In 2007, Lamictal sales were $2.2 billion and Lyrica sales were $1.8 billion.
Roughly 2.7 million Americans have epilepsy, according to government estimates.
Last month, an FDA analysis concluded the medicines are associated with a higher risk of suicidal thoughts and behavior. That echoed findings from other data released by the agency earlier this year.
FDA's Walsh said the agency is proposing the black-box warning based on that data, but will seek the panel's input.
According to the FDA, three of the 11 drugs studied showed no clear signal of suicidal problems.
But other factors made it hard to exclude them from the warning, said Dr. Russell Katz, head of the FDA's division of neurology products. Statistical chance, sample size and the specific way each particular drug works could all be in play, he said in the memo.
"There seems to be no compelling reason to: 1) ignore what appears to be a very clear empirical finding of an increase in suicidality, despite no obvious explanation for this finding, or 2) not generalize the conclusion to other (anti-epilepsy drugs)," Katz wrote.
FDA's Katz said the agency planned to seek its panel's advice on whether to extend the warning to all drugs or just to some of them. The agency usually follows its panels' recommendations.
Pfizer maintains its drug is safe and effective as currently labeled.
Glaxo spokeswoman Sarah Alspach said the results of the FDA's analysis should be included on drug labels for epilepsy drugs and that further research was needed.
FDA's Katz said that at least one company has conducted another analysis for its own drugs "and has come to a different conclusion than the Agency." He did not name the drugmaker but said the company may present its findings Thursday.
Alspach said Glaxo plans to present information to the FDA panel Thursday. It was not immediately clear if other companies, including Pfizer, would also offer data.