CVS subsidiary Omnicare Inc. has agreed to pay $15.3 million to settle claims brought by the U.S. Drug Enforcement Administration and federal prosecutors that it illegally dispensed opiate pharmaceuticals to long-term care facilities, such as assisted living and skilled nursing sites.

The settlement is among the most significant to involve a federal investigation into opioid distribution by a pharmacy, although the Department of Justice has charged individual pharmacies across the country.

In a Wednesday announcement, federal authorities said Omnicare agreed to pay the civil penalties to resolve allegations that it dispensed opioids and other controlled substances without valid prescriptions.

"Omnicare dispensed powerful opioids without valid prescriptions and failed to inform federal authorities of significant losses of opioids and other drugs," said U.S. Attorney Nicola Hanna, of the Central District of California, who reached the agreement, along with the DEA and U.S. attorneys in the Eastern District of California, Colorado, Oregon and Utah. "With the opioid crisis still a very real concern, every entity that handles dangerous drugs will be held accountable to ensure powerful narcotics are properly dispensed and not diverted to the black market."

CVS acquired Omnicare in 2015.

"Omnicare has entered into a settlement agreement with the U.S. Drug Enforcement Administration and certain U.S. attorneys' offices to resolve allegations dating back to 2012 concerning the handling and processing of controlled substance prescriptions at some of its long-term care pharmacy locations," said CVS Health spokesman Mike DeAngelis. "The matter was settled to avoid the expense and uncertainty of potential litigation, and there was no admission of wrongdoing. This matter did not involve any of CVS Health's other businesses, including CVS Pharmacy, CVS Caremark or Aetna."

Several pharmacies, including CVS, are set to go to trial on Nov. 9 against two Ohio counties as part of the multidistrict litigation over the opioid crisis. The counties allege the pharmacies created a public nuisance in distributing opiate pharmaceuticals.

Opioid distributors and manufacturers, such as Insys Therapeutics and Reckitt Benckiser Group, have agreed to settle civil and criminal investigations by the DOJ for more than $1 billion.

According to federal authorities, many of Omnicare's opioid distributions came in "emergency kits," over which it failed to maintain control in violation of the federal Controlled Substances Act. Omnicare allowed the facilities to remove opioids and other controlled substances from the emergency kits before obtaining valid prescriptions, according to Wednesday's announcement. Under its agreement, Omnicare must increase its auditing and monitoring of those emergency kits.