Rising threat of nitazenes joins fentanyl in Canada's toxic drug supply

The toxic drug crisis has taken more than 47,000 lives in Canada since 2016 and the synthetic opioid fentanyl has become a household name. But now, what's believed to be an even more potent class of synthetic drugs is showing up in drug busts across the country: nitazenes.

RCMP in Metro Vancouver, Labrador, and Prince Edward Island have seized nitazenes as part of drug busts this year.

Public health units in Ottawa and Quebec's Eastern Townships have also flagged them.  

Here are some answers to common questions about the class of substances.

Nitazenes are potent, synthetic opioids linked to overdose deaths in many parts of the world, according to the United Nations Office on Drugs and Crime.

No. Nitazenes were created as potential pain relievers in the 1950s.

But they were never approved for clinical use, such as human or veterinary medicines, according to the U.K. Advisory Council on the Misuse of Drugs.

Since 2019, nitazenes have emerged within recreational drug supplies in the United States, Canada and European countries.

In a letter published by The Lancet Psychiatry in 2022, researchers based in Vancouver and Basel, Switzerland, said ultrapotent synthetic substances such as nitazenes are being rapidly produced in what were called homegrown laboratories using legal and easily available ingredients known as precursors. 

Nitazenes are often described as several times more potent than fentanyl, though there's no official estimate. While the potency and street appeal of the recreational drugs are similar, to chemists the structures differ. 

Scientists have relatively little information about how the human body reacts to nitazenes because the chemicals have never gone through clinical trials that offer a chance to find out.

Nitazenes can increase the risk of accidental overdose, especially when combined with other substances that suppress breathing and heart rate such as other opioids or benzodiazepines, the 2022 alert from the Canadian Centre on Substance Use and Addiction said. 

The potency means symptoms can develop quickly before a person gets medical care. One type, isotonitazene, has been implicated in at least 200 deaths in Europe and North America. It was also the most frequently detected nitazene in Canada, a 2022 Health Canada report said.