NEW YORK — The attorneys general of 46 states and two territories are calling on the Food and Drug Administration to make prescription painkillers harder to abuse.

In a letter to FDA commissioner Margaret Hamburg, the attorneys general, writing on behalf of the National Association of Attorneys General, wrote that people who abuse opioid painkillers are increasingly using those that lack tamper-resistant features. While Purdue Pharma's OxyContin (oxycodone) has tamper-resistant features, some, such as North Carolina attorney general Roy Cooper, expressed concerns that future generic versions of the drug - which loses patient protection this year - may not have tamper-resistant features unless the FDA requires them.

"As a specific example, we are concerned with the possibility that generic versions of extended-release opioid prescription drugs and other non-tamper-resistant products may reach the market," the attorneys general wrote. "We applaud the FDA for expeditiously proposing guidelines establishing clear standards for manufacturers who develop and market tamper- and abuse-resistant opioid products while considering incentives for undertaking the research and development necessary to bring such products to market."

The attorneys general included those of Puerto Rico, Guam and every state except Indiana, Virginia, Connecticut and Michigan.