WASHINGTON (AP) – Pfizer Inc., the world’s largest drug maker, is trying to persuade government regulators not to add stern warnings about suicide risks to its best-selling epilepsy drug.

The Food and Drug Administration said Monday that all drugs used to treat seizures should be required to carry “black box” warning labels about increased suicidal thoughts and behavior.

The agency will ask a panel of outside experts to weigh-in on that recommendation at a meeting Thursday.

FDA analysis of nearly 200 studies showed that patients taking anti-seizure drugs were twice as likely to have suicidal tendencies as those not taking the drugs.

The FDA based its analysis on 11 widely used anti-seizure medicines but has stated it wants to add warnings to all drugs in the class. Panelists will be asked to comment on that recommendation.

Seizure drugs were the fifth best-selling class of drugs in the U.S. last year, according to health care research firm IMS Health.

GlaxoSmithKline, which makes the drug Lamictal, has said the FDA’s analysis of suicidal risks is similar to its own conclusions and should be added to drugs’ labeling.

Lamictal was the best-selling epilepsy treatment in the United States last year, with sales of $2.1 billion, according to IMS Health.

Pfizer, however, disagrees with the FDA analysis. The New York-based company markets the nation’s third best-selling epilepsy drug Lyrica with sales of $1.1 billion.

In documents posted online Wednesday by the FDA, Pfizer said its own analysis shows Lyrica is not “associated with an increased risk of suicidal behavior or thinking.”

The company argues that Lyrica works differently than other anti-seizure medications and should not be subject to the generalized warning.

safety and efficacy profile of these important medicines as reflected in our current labeling,” the company said in a statement earlier this week.

The FDA panel of neurologists, statisticians and psychiatrists will hear from government scientists as well as researchers from GlaxoSmithKline and Pfizer. The agency is not required to follow the panel’s advice, though it often does.

Doctors who prescribe the medications have been urging the FDA to take a measured approach to any new warnings, arguing they could cause more harm than good if patients stop taking the drugs completely.

Representatives from the American Academy of Neurology are expected to stress Thursday that epilepsy patients are already prone to depression and suicidal behavior, making it difficult to gauge the negative impact of the drugs.