WASHINGTON — The maker of epilepsy treatment Keppra agreed Thursday to pay more than $34 million for marketing the medication to treat migraine headaches in violation of U.S. drug laws.

The Smyrna-based U.S. subsidiary of Belgian manufacturer UCB pleaded guilty in federal court in Washington to a misdemeanor in connection with the misbranding.

The government had approved Keppra to treat seizures in adults and children with epilepsy. A manufacturer may not market or promote a drug for any use not specified in its approved product label. But prosecutors said UCB claimed studies showed Keppra was safe and effective for treating migraines, without disclosing that UCB sponsored the studies or that the company’s own clinical trial failed to demonstrate such effectiveness.

UCB will pay a $7.55 million criminal fine, forfeit $1 million in assets and pay $25.7 million to resolve civil claims that it promoted off-label uses including migraine, pain, bipolar, mood disorders and anxiety.

The federal government will get $15.8 million of the civil settlement and nearly $10 million will go to state Medicaid programs. The settlement resolves two lawsuits brought by whistleblowers, who will together receive payments of more than $2.8 million from the federal share.

The plea is part of an ongoing Obama administration initiative against health care fraud, including the promotion of drugs for uses the Food and Drug Administration has not approved as safe and effective. The Justice Department said it has recovered more than $5.7 billion in Medicare and Medicaid fraud cases since January 2009.

“UCB put its pursuit of profits ahead of its obligations to patients,” said Ronald C. Machen Jr., U.S. attorney for the District of Columbia. “Today’s guilty plea and UCB’s $34 million payout should remind drug companies that try to cleverly design off-label marketing schemes that we will not allow them to compromise patient safety.”