The company also admitted that, from 2001 through 2006, it marketed the drug to treat schizophrenia. Though the company paid for two studies of the use of Depakote to treat schizophrenia, neither met the goals established for the study, it said.

"When the second study failed to show a statistically significant treatment difference between antipsychotic drugs used in combination with Depakote and antipsychotic drugs alone, Abbott waited nearly two years to notify its own sales force about the study results and another two years to publish those results," it said. During that time, the company continued to promote the drug for the treatment of schizophrenia.

Despite this incident, Abbott will continue to be able to sell its drugs through government programs, a Justice Department spokeswoman said.

Such off-label marketing is not unusual among drug companies, said David Antonuccio, an emeritus professor of psychiatry and behavioral sciences at the University of Nevada School of Medicine. "To a lot of companies, the risks of punishment for off-label marketing are part of the cost of doing business," he said. "I think it's an open question about whether that fine will have the deterrent effect that it's hoped to have."

Antonuccio noted that drugs are not approved for certain indications because evidence does not exist to satisfy the FDA that they are safe and effective for those purposes. "For the drug companies to promote these practices means they're promoting practices that don't have scientific support for safety and efficacy. That's a problem. It exposes people to unknown risk."

Abbott plans to separate into two publicly traded companies by the end of the year.