The federal Drug Enforcement Administration has sued the board that regulates Colorado’s pharmacies, demanding it share information from a database that tracks opioid prescriptions and setting up a clash over patient privacy amid the nation’s overdose epidemic.

The requested information is part of an investigation into whether two unnamed pharmacies broke the law in dispensing opioids and other drugs, according to a DEA agent’s declaration filed in the lawsuit.

“Such violations of law could potentially contribute to significant public harm in Colorado, including the overdose or death of patients,” diversion program manager Kerry Hamilton wrote.

The DEA previously issued administrative subpoenas to the State Board of Pharmacy for the information, which is kept under the state’s Prescription Drug Monitoring Program, or PDMP. The program tracks opioid and other drug prescriptions, including the names of doctors, patients and pharmacies.

State officials refused to provide the information, though, citing patient privacy concerns. That prompted the lawsuit, which seeks a judge’s order enforcing the subpoenas and was filed last week in federal court in Denver. In addition to the Pharmacy Board, the lawsuit also names Patty Salazar, the head of the state Department of Regulatory Agencies, and Appriss, Inc., a Kentucky company the state pays to collect and maintain the PDMP data.

“The Department of Regulatory Agencies is committed to combating the opioid epidemic that remains a devastating issue for many Colorado communities,” DORA spokeswoman Jillian Sarmo wrote in an emailed statement following the lawsuit’s filing. “We continue to work with our partners in other agencies in this fight, but we have an obligation to do so in a targeted and thoughtful manner that ensures the privacy of the hundreds of thousands of individual patients in the state whose personal prescription records have no connection to any criminal activity and whose disclosure has no relevance to any criminal investigation.”

Federal authorities say they need the patient information to link prescribing and dispensing practices to real-world harm. For instance, they argue in the lawsuit that having the name of a patient could tell them whether that patient overdosed after filling a prescription at a shady pharmacy. Or it could show whether a pharmacy should have noticed that a particular patient was filling suspiciously large and potent orders of drugs.

The DEA also says there are legal limits that prevent it from releasing the information, meaning that patient privacy won’t be compromised.

“We recognize that this information is sensitive, but, just as the state does, we respect that sensitivity and will protect the confidentiality of that information from public disclosure,” Colorado U.S. Attorney Jason Dunn, whose office is working with the DEA on the case, said in a statement. “We are disappointed with the refusal to comply with these lawful subpoenas, a refusal that has forced us to seek aid from the court in getting the information we need to carry out important law enforcement investigations aimed at combating the prescription drug abuse epidemic.”

A spokesman for Dunn said no one at the office could comment further.

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The lawsuit and Hamilton’s attached declaration provide little insight into the DEA’s investigation. Hamilton writes that one of the pharmacies ranked among the top pharmacy purchasers over the last two years for three different types of opioids. Both pharmacies — which Hamilton refers to only as Registrant #1 and Registrant #2 — have “been selected by a number of patients of medical practitioners whose own prescribing practices have raised concern with the DEA,” Hamilton wrote.

Hamilton argues in her declaration that Colorado has previously provided federal agents with the types of PDMP data, including patient information, they currently are seeking. She says the state has already handed over some data on one of the two pharmacies now under investigation.

“That information that the DEA obtained from the PDMP has been used to advance its investigation,” Hamilton wrote.

But Sarmo said the state evaluates each subpoena it receives individually.

“The PDMP program’s practices regarding such subpoenas have not changed,” she wrote in an email. “What has changed are the DEA’s subpoenas. The current subpoenas involved in this lawsuit are substantially broader and less targeted than the DEA’s prior subpoenas.”

Sarmo said the state intends to fight the lawsuit. It is uncertain when the case will be resolved.