KNOXVILLE, Tenn. — A new synthetic opioid has been linked to at least 16 overdose deaths in East Tennessee over the past five months, according to preliminary toxicology tests.
According to the Knox County Regional Forensic Center, the drug N-propionitrile chlorphine -- also known as cychlorphine -- was detected in nine overdose deaths between October and December 2025, WZTV reported.
By mid-January, the substance had been responsible for seven more deaths, according to the television station.
“It’s showing up at an exponential rate and at this point, we don’t know if it’s a single batch and done with or if it’s the new future,” Chris Thomas, the chief administrative officer and director of the Knox County Regional Forensic Center, said in a statement last month.
Authorities said the drug has been detected in cases involving other drugs, such as methamphetamine and fentanyl, WZTV reported.
The first Tennessee cases appeared in Knox County and then were detected in the East Tennessee counties of Roane, McMinn, Campbell, Union, Anderson, Claiborne and Sevier, the news release stated.
“This isn’t a drug that has been approved for clinical use, and it’s never been clinically approved to be sold on the market,” Darinka Mileusnic-Polchan, chief medical examiner at Knox County Regional Forensic Center, said in a statement. “We do know it’s more powerful than fentanyl and that naloxone, or Narcan, does not completely block the effects of the drug and multiple doses may be needed to prevent an overdose.”
Mileusnic-Polchan said that early findings suggest that cychlorphine may be more potent than fentanyl, WZTV reported. She added that naloxone, which is commonly known as Narcan, may need several doses to offset the effects of cychlorphine, according to the television station.
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