The new study confirms an animal sedative known as “tranq” has infiltrated Tijuana’s illicit drug supply. Researchers warn that could foreshadow an upward trend in San Diego as well.
An animal tranquilizer prevalent in the eastern U.S. for years has been found in high quantities among drug users in Tijuana, concerning UC San Diego researchers that the illegal anesthetic could soon pervade the illicit drug supply on the West Coast.
Xylazine — a veterinary anesthetic often mixed with fentanyl that is commonly known as “tranq" — has been found in drug trafficking hubs stemming from an epicenter in Philadelphia for about a decade. It's been slowly making its way to California but the drug's prevalence here has been difficult to trace before UCSD’s School of Medicine partnered with the Prevencasa free clinic in Tijuana.
The bi-national study published Thursday in the "Journal of Addiction Medicine" tested urine samples of 23 drug users who came into the community harm reduction clinic over a 24-hour period and found that a majority had xylazine in their system. It's the first academic study to confirm the drug's pervasiveness in San Diego's closest illicit drug hub.
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Dr. Joseph Friedman, resident physician/psychiatrist at UC San Diego and the lead author of the study, said their findings should sound the alarm because "we know the drug supply between Northern Mexico and the U.S. are linked."
"There are a lot of implications for the Mexican government and Tijuana and Baja California health officials and physicians in terms of responding to this crisis," Friedman said. "It also tells us that xylazine is probably something that we need to respond to here in San Diego and Southern California more broadly."
Brian Clark, Special Agent in Charge of the San Diego division of the Drug Enforcement Administration, confirmed San Diego is beginning to see an uptick.
"It's not something we've seen in California for a long period of time," Clark said. "The drug trends tend to move from the east coast back to the west and xylazine was present in Pennsylvania and New York, in a lot of those open-air drug market areas. Now, we're starting to see that on our streets here locally in San Diego."
Xylazine, which is not used on its own but mixed with other powerful and concerning drugs like fentanyl or heroin, was first declared a public safety threat by the Biden Administration in 2023 but the FDA warned health care providers of its detection in 2022.
Unlike fentanyl, tranq can't be treated with the anti-overdose drug naloxone, increasing the public health ramifications of its use. Many drug users are also likely not aware it's being added to other drugs.
Friedman described instances where medics in Tijuana would administer naloxone to suspected overdose patients to little avail. In one case, a man known to the Prevencasa clinic was found face-first on the ground showing symptoms of an overdose. He was given naloxone and resumed breathing but was unconscious for another 20 minutes and needed several other services once awake. He was given a urine test, which confirmed xylazine, fentanyl and meth in his system.
"Patients were still sedated on xylazine, which means they needed a lot of extra services, helping them protect their airway, keeping the scene safe, and a number of other measures," Friedman said. "So our team really had to adapt and respond to this new challenge."
Local leaders have already begun discussions on how to handle a possible public safety crisis. In 2023, San Diego Mayor Todd Gloria called it a top priority among California's big city mayors.
The UC San Diego doctor said he hopes his team's research encourages doctors and vulnerable patients to become educated about the risks associated with the drug and promotes a conversation among the health care community. The research team has published a guide to aid in responding to a xylazine overdose — methods like distributing testing strips to drug users similar to those used with fentanyl — but it hasn't been widely implemented across Southern California.
"This is such a new public health crisis that a lot can be done just by building understanding and awareness," Friedman said.
"It's important for all of us here in California to understand that xylazine is arriving and we need to be ready for this because it presents really unique health risks for people who are exposed to it."
