Oxycontin is a leading painkiller and 18th most prescribed drug billed to Medicare Part D, according to a Wall Street Journal expose on the rise of opioid prescribing in the U.S. It’s also one of the few opioids whose makers continue to be parties in a federal lawsuit filed last year by the City of Chicago.

Chicago’s massive suit alleges painkiller drug companies have misled prescribers and patients, leaving many woefully addicted and the city with enormous costs for treating them. Chicago states that it paid about 400,000 claims related to opioid prescriptions since 2007, costing almost $9.5 million.

Last week, Judge Jorge Alonso of the U.S. District Court for the Northern District of Illinois dismissed the city’s claims against painkiller makers Johnson & Johnson and Actavis Plc. Without ruling on the merits of the case, however, Alonso did not exclude several other opioid makers, including Purdue Pharma Inc., the maker of OxyContin. The City of Chicago has until June 8 to appeal the exclusion of Johnson & Johnson and Actavis Plc.

Alonso said there were sufficient allegations that Purdue “made misstatements about opioids” on its websites and sought to mislead doctors and consumers, according to Bloomberg News. As recently as 2008, misuse of painkilling drugs killed more people than heroin and cocaine combined, according to the U.S. Centers for Disease Control and Prevention.

While OxyContin is a leading opioid billed to Medicare Part D, it was not the most popular in 2013. That distinction goes to the generic painkiller hydrocodone acetaminophen, which was the drug most widely prescribed to Medicare beneficiaries, according to the Wall Street Journal. Over 8 million Medicare beneficiaries were prescribed it in 2013.