NASHVILLE, Tenn. (WKRN) — Two designer drugs associated with illicit opioid use are spreading in Tennessee, according to a study by the Nashville-based forensic toxicology and healthcare laboratory, Aegis Sciences Corporations.

The study examined positive fentanyl tests from 30 different states, including Tennessee, and found nearly 70% of the positive fentanyl samples also tested positive for at least one other novel psychoactive substance, which are unregulated, mind-altering drugs with no legitimate medical use designed to mimic the effects of controlled substances.

“This is important because in some cases these analogs are more potent than fentanyl,” said Dr. Andrew Holt, Aegis Sciences Corporation’s clinical pharmacist.

The most commonly detected substance combined with fentanyl in the study were designer opioids, including nitazine, which is creeping into Tennessee’s illicit drug supply, according to Holt.

“There have been both federal and international efforts to schedule and control fentanyl analogs, so we’re beginning to see a trend toward these nitazine analogs being incorporated into the illicit drug supply to take the place of the fentanyl analogs that are being pressured out of the illicit drug supply,” Holt said.

Nitazine is up to 40 times stronger than fentanyl. First developed in the 1950s, the drug has never been approved for use in the U.S.

However, it’s frequently popping up in positive fentanyl samples, along with other new psychoactive substances including designer benzodiazepines and synthetic cathinones, according to Holt.

“Designer opioids, xylazine, designer benzodiazepines, they can all lead to central nervous system depression which increases an individual’s risk of an overdose,” Holt said.

Xylazine, which is a large animal tranquilizer, was detected in more than 40% of the positive fentanyl samples, the study found.

That is especially concerning to medical professionals because Xylazine, often referred to as tranq, does not respond to the overdose-reversing drug, Naloxone, increasing the risk of death.

“It’s being increasingly identified as a high-risk drug for overdoses,” Holt said.

Xylazine can also cause users’ flesh to rot. News 2 previously spoke to a woman in recovery who said she didn’t realize she was using the drug until she began noticing black, necrotic skin on her arms.

“One day one of the black, necrotic skin pieces started coming off, so I kind of cut it off, so from then on I started cutting the black, necrotic skin off myself,” Tracey McCann said. “I didn’t know amputation could be a possibility. I just knew I had to take care of my arms.”

Holt told News 2, the study’s findings will help both patients and medical providers address illicit drug use.

“The biggest takeaway from this is the more providers are aware of what’s present and what their individual patients are exposed to, they can have better conversations; have better clinical decision making,” Holt said. “From a public health perspective, these can better inform harm reduction plans, especially for drugs like xylazine where it’s not going to respond to some of the mainstays of harm reduction, which of course is naloxone.”