The drug is suspected in up to 2,000 deaths among millions who took it as an appetite suppressant over three decades, according to a 2010 study.
ADVERTISEMENTA French pharmaceutical company was on Monday found guilty of "aggravated deception" and "manslaughter and involuntary injury" after one of its drugs was prescribed as a diet pill and blamed for the deaths of hundreds of people.
Servier Laboratories was also fined €2.7 million but cleared of its charges for fraud in a case that grew into France's biggest modern health scandals.
The 6,500 plaintiffs had accused the company of putting profits ahead of patients' lives by allowing its diabetes drug, Mediator, to be widely and irresponsibly prescribed as a diet pill.
The drug is suspected of causing up to 2,000 deaths among millions who took it as an appetite suppressant over three decades, according to a 2010 study. Doctors also linked it to heart and lung problems.
The company was tried for charges including manslaughter, involuntary injury, fraud, and influence trading. Investigating magistrates concluded that Servier covered up the drug's effects on patients.
Sylvie Daunis, who presided over the ruling at a Paris court, said the company has "undermined confidence in the health system."
"Despite the knowledge they had of the risks incurred for many years, (...) they never took the necessary measures and thus deceived" consumers of Mediator, she added.
Prosecutors had asked for the company to be fined nearly €15 million and for the only Servier executive accused of involvement still alive today, Dr. Jean-Philippe Seta, to be sentenced to three years in jail and to pay a fine of €278,000.
Seta was sentenced to a four-year suspended prison term and fined €90,600. He will also have to pay millions of euros in damages to the victims.
France's national medicines agency (ANSM) was also slapped with a €303,000 fine for colluding to mask the drug's danger.
Plaintiffs have also asked for damages totalling €1 billion.
Servier had asked for an acquittal, arguing that it wasn't aware of the risks associated with Mediator before 2009 and that it never pretended it was a diet pill.
Euronews has contacted Servier and the ANSM for comment.
One doctor flagged concerns as far back as 1998 and testified that he was bullied into retracting them. Facing questions about the drug’s side effects from medical authorities in Switzerland, Spain and Italy, Servier withdrew it from those markets between 1997 and 2004.
It took an independent investigation by another worried French doctor before the company suspended sales in its main market in France in 2009.