Animal tranquilizer being mixed with fentanyl in Toronto's illicit drug supply, experts warn

A powerful drug used primarily by veterinarians to sedate animals is increasingly showing up in Toronto's unregulated drug supply, community health workers warn.

Medetomidine, a tranquilizer intended for use only in animals, is being found in 80 per cent of fentanyl samples tested by Toronto's Drug Checking Service, which provides community members with information about the contents of their drugs.

Hayley Thompson, managing director of Toronto's Drug Checking Service, says medetomidine is being mixed with fentanyl, a short acting opioid, because of the belief that it enhances its sedative effects.

Medetomidine, also known as rhino tranq, was first detected in the city's drug supply in December 2023.

"We're definitely seeing people being very concerned in the community with what it is that they're consuming," Thompson said on Tuesday.

Thompson said the combination of medetomidine and fentanyl, which are both sedatives, means overdoses are hard to reverse. Naloxone, which is used to reverse opioid overdoses, can reverse the effects of fentanyl but it will not reverse the effects of medetomidine.

"What we see is a fentanyl supply that is becoming increasingly volatile, increasingly toxic. And we're sort of an early warning system here where we are telling folks about these new contaminants," Thompson said.

Thompson said when fentanyl was first detected in Toronto, it was a contaminant of heroin.

"But now what we see is fentanyl being contaminated," she said.

Thompson said a co-ordinated approach at the provincial level is needed to address the toxic opioid supply crisis.

According to Toronto's Drug Checking Service, medetomidine may put people in a "deep state of unconsciousness," reduce blood pressure and heart rate and slow down breathing.

Dr. Emily Austin, an emergency physician at St. Michael's Hospital, told CBC Radio's Metro Morning on Tuesday that reports out of the U.S., particularly in Philadelphia, show the drug has increased hospitalizations, including stays in intensive care units.

Austin, also the medical director of the Ontario Poison Centre, said if a person has an overdose of fentanyl or medetomidine, they might experience more sedation than if they only took fentanyl.

That means they might stay in the emergency department a little bit longer and may need an IV because their blood pressure is lower.