A new, legal synthetic opioid as deadly as fentanyl has been implicated in scores of deaths in the U.S.

The appearance of isotonitazene in North America’s narcotic food chain seems to confirm fears that last year’s ban by China of the non-medical use, supply, and production of synthetic opioids such as fentanyl would fail to shut the door on the lab drugs fueling America’s opioid crisis.

Barry K. Logan, a leading international authority on forensic toxicology and chief scientist at forensic firm NMS labs, said his colleagues have identified isotonitazene—which has a potency equivalent to fentanyl—in samples from more than 200 deceased drug users in the midwest and northeast since August last year.

“Isotonitazene is the most persistent and prevalent new opioid in the U.S.,” said Logan, adding that he is now seeing 40 to 50 isotonitazene-related deaths per month in the U.S. compared to about six per month last summer.

Logan said his team had identified only a dozen new opioid substances last year in the U.S., but that isotonitazene had swiftly made a name for itself. “Most new opioids we see once or twice, but isotonitazene is the one that’s taking off.”

It has also reached Canada. In March, isotonitazene was found in 1,900 fake pharmaceutical pills in Nova Scotia and Newfoundland. The drug has been pressed into tablets to resemble Dilaudid, or hydromorphone. Dilaudid is a much-desired, highly euphoric synthetic opioid similar to oxycodone, aka Oxycontin.

In April 2019, in a move designed to appease President Trump, China banned all possible variants of the deadly synthetic opiate fentanyl. Trump had complained bitterly over China's perceived inaction on its fentanyl trade, and he threatened economic punishment in return.

But within months of the Chinese blanket ban in April 2019 on fentanyl and all its derivatives, chemists in Chinese labs plundered medical literature and drug patents and produced this new, legal series of drugs that are just as powerful as fentanyl: a family of drugs called benzimidazoles, of which isotonitazene is one.

Isotonitazene is legal to export from China and is not specifically banned in the U.S., Europe or China. America’s Analog Act would cover it as a derivative of a banned substance, but no case has come to court yet. It could take years before it is scheduled in the U.S. and internationally.

Chemists in Shanghai and other major manufacturing centers are still out-inventing lawmakers the world over, quickly synthesizing new, legal variants of recently banned drugs. Isotonitazene and several variants of it are now being sold online, legally by Chinese suppliers offering bulk deals.

Previously, isotonitazene was a niche drug used by internet drug geeks, or psychonauts, Logan said. But he now, as happened with fentanyl, there are bags of heroin on sale on the streets in the U.S. with mixtures containing isotonitazene, with users having no idea what they are buying.

Online forums like Reddit have been abuzz for several months with news of new, potent, legal opioids of the benzomidazole class that are available across the net from China. One user there wrote: “That etonatazine is ridiculous strong. It hits quick and hard and fades, but you’re left with crazy opiate tolerance. It takes a while to feel anything else for a while.”

Isotonitazene has also been spotted in the EU, said Michael Evans-Brown of the European Monitoring Centre for Drugs and Drug Addiction's early warning system for new drugs. “Isotonitazene has been available in Europe since at least April 2019. It is sold as a replacement to controlled opioids on the surface web, darknet markets, and at street-level,” he said.

“One important concern is that people who use opioids have no experience of how to use isotonitazene,” Evans-Brown said. “It can increase the risk of overdose, and this risk is especially high when people don’t know they are using it, as in the case of fake medicines containing the substance recently reported in Canada.”

Discovered in 1957 by a Swiss pharmaceutical firm, isotonitazene is an analogue of its banned parent compound, etonitazene, which was discovered in 1956 and is itself 60 times more potent than morphine.