The maker of drugs that treat opioid addiction posted an adjusted operating profit of $24 million (18.49 million pounds) for the second quarter ended June 30, compared with $89 million a year earlier.

Last week, Indivior said it agreed to pay $600 million and have a subsidiary plead guilty to a felony charge to resolve U.S. allegations that it engaged in an illegal scheme to boost prescriptions of its opioid addiction treatment Suboxone.

The company's Suboxone had been among the main treatments for addiction through a growing epidemic of opioid abuse in the United States.

But revenue from the United States, which constitutes about 80% of its sales, was affected by the rise in generic competition for Suboxone Film and lower new patient enrolments for its opioid treatment Sublocade and schizophrenia drug Perseris following the stay-at home orders.

The U.S. net revenue during the quarter fell 34% to $107 million.

(Reporting by Aakash Jagadeesh Babu in Bengaluru; editing by Uttaresh.V)