This study backs up ongoing concerns voiced regarding the practice of pharmaceutical reps providing gifts to physicians.  http://www.medscape.com/viewarticle/863304?nlid=105107_2981&src=wnl_dne_160517_mscpedit&uac=249582HK&impID=1099469&faf=1 

Another very in-depth article on this http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2811591/

How does this relate to the Opioid Epidemic?  Take a look at this article that details Purdue Pharma and their role in marketing Valium and Oxyconting: http://theweek.com/articles/541564/how-american-opiate-epidemic-started-by-pharmaceutical-company