old, 2014, but for background
https://www.scientificamerican.com/article/how-much-are-drug-companies-paying-your-doctor/
Those who read the fine-print disclosures accompanying medical journal articles know that doctors often have relationships with several companies that compete in a drug category (such as heart drugs or those for schizophrenia). Our data bear that out.
Some highly sought-after key opinion leaders, as they are known in the industry, work for half a dozen or more companies in a given year.
Dr. Marc Cohen, chief of cardiology at Newark Beth Israel Medical Center, received more than $270,000 last year for speaking or consulting for six companies listed in Dollars for Docs. He is a prolific researcher and author.