The US Justice Department charged GlaxoSmithKline for promoting its antidepressant drugs Paxil and Wellbutrin as treatments for conditions for which they had not been approved by regulators, such as depression in adolescents, according to Agence France-Presse.
The company also held back data and made unsubstantiated claims about its diabetes drug Avandia, CNN Money reported.
"Today's multi-billion dollar settlement is unprecedented in both size and scope," James M. Cole, a deputy attorney general, said in a statement cited by CBS News.
"It underscores the Administration's firm commitment to protecting the American people and holding accountable those who commit health care fraud."
Reuters said GlaxoSmithKline, one of the biggest health care and pharmaceutical companies in the world, will pay $1 billion in criminal fines and $2 billion in civil fines.
GlaxoSmithKline chief executive Andrew Witty expressed “regret” for the misdemeanors and said the company had “learnt from the mistakes that were made.”
“We have fundamentally changed our procedures for compliance, marketing and selling,” Witty said in a statement.
“When necessary, we have removed employees who have engaged in misconduct. In the last two years, we have reformed the basis on which we pay our sales representatives and we have enhanced our ability to ‘claw back’ remuneration of our senior management.”