GlaxoSmithKline has been socked with $US3 billion in fines by US authorities over charges it marketed drugs for unauthorised uses, held back safety data and cheated the government's Medicaid program.
The Justice Department said GSK was fined over misbranding its drugs Paxil and Wellbutrin, and for holding back data while making unbacked claims for its diabetes drug Avandia.
GSK pleaded guilty and agreed to the fines in what the department called the largest health care fraud settlement in US history.
GSK, one of the world's largest health care and pharmaceuticals companies, admitted to charges that it had promoted antidepressants Paxil and Wellbutrin for uses not approved for by US regulators, including treatment of children and adolescents.
The British drugmaker also conceded charges that it held back data and made unsupported safety claims over its diabetes drug Avandia.
Altogether it will pay $US1 billion in criminal fines and forfeitures over charges relating to the three drugs.
In addition, the company will pay $US1.7 billion in civil fines for illegal promotion of those drugs as well as others; paying kickbacks in their marketing; and making unsubstantiated claims about Avandia's safety and efficacy.
And separately, GSK is being fined $US300 million to settle charges it underpaid rebates it owed to the US Medicaid program.
GSK chairman Sir Andrew Witty said in a statement that the problems originated in a "different era" and the company had "fundamentally" changed its procedures for compliance, marketing and selling its products, and has removed employees involved in misconduct.
"On behalf of GSK, I want to express our regret and reiterate that we have learnt from the mistakes that were made."