The invention of fentanyl as a drug comes from the Belgian doctor Paul Janssen, the founder of Janssen Pharmaceuticals, widely regarded as one of the most invented drugs in the world.

He has more than 100 drug patents in his life and has published more than 850 papers. He has made significant contributions to medical fields such as psychiatric treatment, analgesia, anesthesia and infectious disease treatment.

Four of the drugs he invented with the team were included in the current list of essential medicines of the World Health Organization, including fentanyl.