There were lawsuits until "Drug industry hired dozens of officials from the DEA as the agency tried to curb opioid abuse"

 "In 2005, the DEA began to crack down on companies that were distributing inordinate numbers of pills such as oxycodone to pain-management clinics and pharmacies around the country. 

Since then, the pharmaceutical companies have hired at least 42 officials from the DEA...

also see:
"Ex-DEA official says Congress is protecting drug makers"

A former top Drug Enforcement Administration (DEA) official has accused Congress of putting pharmaceutical company profits ahead of public health in the battle to combat the US’s prescription opioid epidemic.

Joseph Rannazzisi, head of the DEA office responsible for preventing prescription medicine abuse until last year, said drug companies and their lobbyists have a “stranglehold” on Congress to protect a $9bn a year trade in opioid painkillers claiming the lives of nearly 19,000 people a year.