CDN: Animal tranquillizer xylazine is now in Canada’s street drug supply.

A powerful animal tranquillizer that has been infiltrating street drugs in the United States has been increasingly showing up in Canada’s illicit opioid supply — a phenomenon that has experts “deeply concerned.”

Xylazine, a sedative and analgesic normally used in veterinary medicine to sedate large animals such as cattle or horses, has been wreaking havoc in parts of the U.S., notably in Philadelphia, where it was found in 90 per cent of dope samples tested in the city in 2021, according to data released by Substance Use Philadelphia.

The presence of xylazine in opioids in the U.S. prompted a warning from the U.S. FDA in November 2022, alerting health-care professionals to “increasing reports of serious side effects” from the drug, known as “tranq.”


The Canadian Community Epidemiology Network on Drug Use (CCENDU) issued its own alert last July identifying the emerging presence of xylazine in a small number of opioid samples tested in B.C., Manitoba, Ontario, Quebec and Nova Scotia.

Since then, its presence in Canada has grown, according to drug test samples and coroner’s reports in B.C. and Ontario.

Karen McDonald, the lead for Toronto’s Drug Checking Service, says the drug first started showing up in Canada’s unregulated opioid supply in September of 2020, but since then its presence in the fentanyl supply has increased.

“Earlier this year we were finding xylazine in about 20 per cent of the fentanyl samples that we were checking,” she said.

While that number has since decreased to about six per cent of recent samples, McDonald says most people who end up with tranq in their fentanyl don’t know it’s there.

“Our understanding was that most folks in Toronto were not choosing to use xylazine, it was just kind of being cut into their drugs unknowingly. So it certainly is a problem.”
Repeated xylazine exposure can cause significant harm. It does not respond to naloxone — a medication that can reverse the effects of opiates — and makes overdoses from opioids mixed with this sedative more challenging to treat, McDonald said.

People who have taken drugs containing xylazine can also develop severe, necrotic skin ulcers, according to the U.S. Food and Drug Administration. These sores have led to amputations among some repeated users in the U.S., according to a report earlier this week in the New York Times.

Dr. Paxton Bach, an addiction medicine specialist at St. Paul’s Hospital in Vancouver and the co-medical director of the BC Centre on Substance Use, says the drug has been showing up in British Columbia’s drug supply, although not to the extent that it has in the U.S.

He estimates about five per cent of opioids being tested in B.C. recently have xylazine in them, but added that it’s still unclear what this will mean for those like him who treat people dealing with drug addiction, overdose and withdrawal.

“The effects of that in a drug supply are still not fully known. But it leads to the increasing unpredictability of any given sample of drugs and can lead to really profound effects for people who are using the drugs — blackouts, loss of memory and other medical consequences,” he said.
Bach also highlighted the particularly troublesome side effect of slow-healing skin lesions.

“I expect we’re going to start to see more of that in Canada,” he said.

“(I’m) deeply concerned. The speed at which the drug supply is evolving is outstripping our response.”

Trying to determine how prevalent xylazine is in Canada is not easy to answer, however, as the situation is different across the country, said Doris Payer, an addiction neuroscience expert and knowledge broker for the Canadian Centre on Substance Use and Addiction.

In some cases, it may be that xylazine hasn’t made its way into some provinces or territories, but it’s also true that drug testing, monitoring and surveillance varies across the country, Payer said.

“There’s no blanket statement we can make, but we have seen it,” she said.

“It is around … it’s just hard to know what’s going on.”

Another complicating factor in identifying its prevalence is that xylazine is not readily identified by routine toxicology screens and therefore may be under-detected, according to the FDA.

Additional testing techniques are required to detect xylazine in specimens like blood or urine, the U.S. agency said in a letter to stakeholders last November providing clinical information about risks of the drug.

“Even with appropriate testing, overdoses involving xylazine may be underdiagnosed due to xylazine’s rapid elimination from the body, with a half-life of 23-50 minutes,” the FDA letter stated.

While some people may be taking street fentanyl not knowing xylazine has been cut into it as a filler, others are actually seeking it out, Payer added.

“According to our CCENDU representatives, some people seek out xylazine because it can change the effects of, let’s say, fentanyl or something that they’re intending to take,” she said.

“But many also take it unintentionally just because it’s in the unregulated market and people just aren’t aware that it’s in the samples that they’re using.”

Experts and front-line workers have been raising alarm about Canada’s drug supply becoming more toxic and unpredictable, due to an increasing trend of opioids like fentanyl and heroin being mixed with other drugs, including benzodiazepines and xylazine.

The presence of these powerful sedatives in the opioid supply means naloxone is not fully effective, as this antidote does not work on benzos or xylazine.


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