Virginia ? The maker of the powerful painkiller OxyContin and three of its current and former executives pleaded guilty Thursday to misleading the public about the drug’s risk of addiction, a federal prosecutor and the company said.

Purdue Pharma L.P., its president, top lawyer and former chief medical officer will pay $634.5 million in fines for claiming the drug was less addictive and less subject to abuse than other pain medications, U.S. Attorney John Brownlee said.

The plea agreement settled a national case and came two days after the Stamford, Conn.-based company agreed to pay $19.5 million to 26 states and the District of Columbia to settle complaints that it encouraged physicians to overprescribe OxyContin.

Privately held Purdue learned from focus groups with physicians in 1995 that doctors were worried about the abuse potential of OxyContin. The company then gave false information to its sales representatives that the drug had less potential for addiction and abuse than other painkillers, the U.S. attorney said.