Attorneys General from 42 U.S. states and territories are urging the U.S. Food and Drug Administration (FDA) to require drug companies to ensure generic prescription opioids have abuse-deterrent features.

Some brand-name painkillers, such as OxyContin, already have abuse-deterrent features, the Lexington Herald-Leader reports. The attorneys general said they are concerned that as generic versions of opioids become available, the drugs’ manufacturers will not incorporate abuse-deterrent features. Some drug companies have resisted adding the features because of the cost, the article notes.

In a letter to FDA Commissioner Margaret Hamburg, the attorneys general wrote that they “respectfully request that the FDA provide clear and fair regulatory standards for the incorporation of abuse-deterrent technologies into generic opioids.”

“Requiring abuse-deterrent formulations for generic opioids is a common sense improvement that provides us another important tool to help fight this epidemic,” Kentucky Attorney General Jack Conway said in a news release.

Last week, the attorneys general from 28 states asked the FDA to reassess its decision to approve Zohydro ER (extended release), a pure form of the painkiller hydrocodone. In a letter to Commissioner Hamburg, the attorneys general said they believe the approval of Zohydro ER “has the potential to exacerbate our nation’s prescription drug abuse epidemic because this drug will be the first hydrocodone-only opioid narcotic that is reportedly five to ten times more potent than traditional hydrocodone products, and it has no abuse-deterrent properties.”