KNOXVILLE - Last year a new synthetic opioid hit East Tennessee and between late October and through December, it appeared in nine overdose deaths. As of mid-January, the same designer drug was linked to seven more deaths, according to preliminary toxicology tests.

The new drug is called N-Propionitrile Chlorphine, or cychlorphine for short. Not much is known about it at this point, but it is spreading quickly. On Jan. 16, the UK Harm Reduction Hub – a University of Kentucky initiative that studies the state’s street drug supply – found cychlorphine in a syringe from Fayette County, KY, which is less than a three-hour drive from Knoxville. On Tuesday, the Hub announced that “cychlorphine has now been associated with an increase in fatal overdoses.”

“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,” said Chris Thomas, the chief administrative officer and director of the Knox County Regional Forensic Center.

Thomas added that the overdose deaths so far have appeared in combination with other drugs – mostly methamphetamine and fentanyl.

The initial Tennessee cases appeared in Knox County, then spread to Roane, McMinn, Campbell, Union, Anderson, Claiborne and Sevier counties.

“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,” said Dr. Darinka Mileusnic-Polchan, chief medical examiner at Knox County Regional Forensic Center. “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.”

As experts continue to learn more about the drug, it appears to have originated in China in 2024 before moving to Europe, Canada and the U.S. in mid-2025, according to the Center for Forensic Science Research and Education, based in Pennsylvania. The Knox County Forensic Center first discovered the drug in Tennessee in late November 2025 when the substance appeared in a Roane County overdose death. As more information came in, officials were able to date a Knox County case back to October.

N-Propionitrile Chlorphine is a non-fentanyl-related synthetic opioid. Sometimes called NSOs, or new synthetic opioids, they are a diverse group of synthetic, or man-made opioids, that are structurally different than fentanyl and fentanyl analogues.