PharMerica has been charged in a False Claims Act lawsuit by the federal government.

The suit stems from a 2009 whistleblower complaint filed by Jennifer Denk, a former PharMerica employee. The company routinely filled nursing homes’ orders for oxycodone and other Schedule II narcotics, even if there was not a proper prescription written by a doctor, Denk alleged. PharMerica also billed Medicare for these drugs, according to the suit.

“The complaint that we are filing today reflects the abiding commitment of the Justice Department to the qui tam process, encouraging people with information about alleged fraud and abuse to report it in a timely and effective manner,” said James L. Santelle, U.S. Attorney for the Eastern District of Wisconsin on Friday.

PharMerica “disputes the premises of the lawsuit” and will “vigorously defend itself,” the company stated Monday.