Durogesic is sold as a skin patch to control ongoing moderate to severe pain and is often prescribed in cancer cases. It contains fentanyl, an opioid which, if misused, can lead to death by overdose.

The French Autorite de la Concurrence said J&J’s Janssen had “repeatedly intervened” to block the approval processes in France of Durogesic’s generic copies and disparaged them when in contact with doctors and other healthcare professionals.

The company disputed the finding.

“We firmly object to the statements contained in the competition authority’s release and to its assessments,” a spokeswoman for J&J said in an emailed statement, adding that the company was studying its options.

The case was brought to the watchdog by German firm Ratiopharm, later acquired by Israel’s Teva pharmaceuticals, after Durogesic lost its patent in 2005.

In 2013, France’s Sanofi was ordered to pay 40.6 million euros for disparaging generic competition to its Plavix blood thinner.