(NewsNation) — A synthetic opioid first developed in the 1950s is falling back into the hands of Americans.

Nitazines, nicknamed Frankenstein opioids, are up to 40 times stronger than fentanyl. Fentanyl is already 50 times more powerful than heroin.

Nitazine comes in powder, pill and liquid form and is often laced into substances, including fentanyl or heroin. It’s potentially lethal or can cause a more severe onset of withdrawal symptoms, according to GoodRx Health.

As the supply of street drugs rises, the rise in nitazine-related deaths is increasing the public health response to the addiction crisis in a growing number of cities across the U.S.

“With the opioid crisis, drug dealers are looking to meet the needs of the market, and because it is getting harder and harder to get their hands on fentanyl and oxycodone, they are looking for substitutes,” said Dr. Joe Schwarcz, a chemistry professor and McGill University office for science and society director.

A Centers for Disease Control and Prevention review of overdose deaths in Tennessee found a four-fold increase in deadly overdoses linked to nitazine in the last two years. The state saw an increase in nitazine-related overdoses from 10 to 42 between 2020 and 2021, per the CDC report, which noted the figures are likely an undercount.

The agency also reported that nitazine-related overdoses could require up to four doses of naloxone, the opioid reversal drug.

Schwarcz said anyone with a background in organic chemistry can make nitazine and they can be produced in so-called “underground laboratories.”

However, he said it appears that the samples that are showing up on America’s streets are coming from China.

“China has a large number of unregulated labs that will produce anything that the customer wants. It seems that they have latched on to this and they are making, they’re synthesizing the nitazine, which incidentally is a family of compounds of several different ones,” Schwarz said. “They are selling it to drug dealers in North America.”

The Drug Enforcement Administration flagged the emergence of the drug mixed into heroin or fentanyl in the Washington, D.C. area last June.

The DEA said the continued evolution of synthetic opioids like nitazenes is “a public health concern” by November.