They have.[1][2] This has substantially contributed to increased demand for imported heroin and synthetic opiods which are substitutable for perscription pain killers to prevent withdrawal.[3]

[1] Former Health Minister of Guyana, Dr. Noel Blackman, Sentenced for Running “Pill Mill” in Long Island, https://www.dea.gov/divisions/nyc/2017/nyc051217.shtml

[2] Manhattan U.S. Attorney Announces Charges against Owner of Bronx Clinic and 23 Other Individuals Involved in Illegal Distribution of More Than Five Million Oxycodone Pills, https://www.dea.gov/divisions/nyc/2014/nyc020514b.shtml

[3] Unintended consequences: Why painkiller addicts turn to heroin, http://www.cnn.com/2014/08/29/health/gupta-unintended-conseq...