A judge in Arkansas, US, has ordered Johnson & Johnson (J&J) to pay a $1.1bn fine after a jury determined that the company misled and hid risks of its antipsychotic drug Risperdal (risperidone).
J&J and its subsidiary Janssen Pharmaceuticals had been fighting a case with the state of Arkansas over marketing practices for the drug since 2007.
The judge, Tim Fox, fined J&J $5,000 each for almost 240,000 separate violations of the state's Medicaid fraud law, with J&J to pay the amount back to Arkansas state.
Medicaid is a government-funded US public health programme for US citizens on low incomes.
The attorney general for Arkansas, Dustin McDaniel, described the judge's decision as a “big win” for the state.
He said: “These two companies put profits before people, and they are rightfully being held responsible for their actions.”
Major side effects that Risperdal has been linked to included weight gain, diabetes and an increased risk of stroke.
In a statement, Janssen said: "We are disappointed with the judge's decision on penalties. If our motion for a new trial is denied, we will appeal."
It continued: “The state did not show any Arkansas patient was ever harmed by using Risperdal.”
The Arkansas ruling is the second major payout for J&J this year after a lawsuit in Texas also accused the healthcare giant of misleading in its marketing of Risperdal, leading to a $158m settlement.
In 2012, J&J was ordered to pay civil penalties of $327m to the state of South Carolina, although this case is now under appeal.
Other states that have brought action against the company over Risperdal marketing pratices include West Virginia, Massachusetts, Montana, New Mexico, Pennsylvania and Louisiana, although suits in Pennsylvania and West Virginia have found in favour of the company.