Xylazine -Tranq dope - An Emerging Magnifier of the Opioid Crisis

A Deadly Combination

Xylazine is a drug used by veterinarians for decades as a sedative and pain reliever on cattle, horses and other animals.  Studies for human use more than 50 years ago were terminated because of intolerable side effects.  It has never been approved or intended for human use.  Since the early 2000’s, but with a dramatic escalation in the last 5 years, xylazine has been detected in the illicit US drug supply, most commonly combined with fentanyl.  In the most recent data, fentanyl-xylazine combinations have been identified in 48 states. In 2022, xylazine was detected in 90% of street opioid samples tested in Philadelphia.    In a 2023 report from Tennessee, the fatal overdoses of fentanyl mixed with xylazine increased 352% from 2019 to 2022.  In April, 2023, the White House Office of Drug Control Policy designated fentanyl combined with xylazine as “an emerging threat to the United States.”  The administrator of the US Drug Enforcement Administration (DEA) concluded in early 2023 that “Xylazine is making the deadliest drug threat our country has ever faced, fentanyl, even deadlier.”

Xylazine isn’t an opioid like morphine, heroin or fentanyl and isn’t affected by the opioid reversal drug naloxone (Narcan).  Xylazine acts in the central nervous system depressing sympathetic outflow leading to sedation, analgesia and muscle relaxation. Other xylazine effects include lowered blood pressure, slowing of the heart rate, hyperglycemia and respiratory depression. Unfortunately some of these effects are additive to those seen with fentanyl overdose, increasing the risk of fatality.

 Xylazine may have been initially used as a filler in illicitly manufactured fentanyl tablets because of its low cost - a kilogram of xylazine can be purchased online from Chinese suppliers for as low as $6.  The fact that some users claim that xylazine prolongs the short-lived fentanyl high is likely another driver for the combination. 

Xylazine represents a relatively new entrant into the illicit  drug supply.  Street names for the drug include tranq dope, philly dope, sleep-cut, and horse tranquilizer.   Unlike fentanyl and other opioids which can be reversed with naloxone, there is no antidote for xylazine.  In the Tennessee study there were fatal xylazine/fentanyl overdoses despite treatment with Narcan.  Illicit fentanyl users may be unaware they are also taking xylazine.  Only recently have high sensitivity rapid test strips to detect xylazine become available.  While Narcan should be administered in all suspected opioid overdoses, when xylazine is present patients may require additional medical support including intubation and oxygen to improve breathing.  IV fluids may be required to raise blood pressure.  Clearly management of a xylazine/fentanyl overdose may be more complex than a fentanyl overdose alone.  

Xylazine causes open skin ulcerations, often progressing to deep wounds down to tendons and even bone.  These don’t only occur at injection sites and may occur with oral, intranasal or inhalational use.  These ulcers usually occur on the limbs and require careful, intensive wound care.  Unfortunately,  these very nasty wounds are a barrier for some patients who need shelter or inpatient rehabilitation.  The appearance of these skin ulcers and deep sores have earned xylazine another name - the zombie drug.

What should be done now

A Congressional Research Service report has raised the possibility of a congressional action which would categorize xylazine as a schedule II drug under the Controlled Substances Act  and subject it to regulation by the FDA.  This important first step would impose penalties for illicit manufacturing and trafficking of the drug as well as impose quotas on production and importation.  

Obviously education is paramount. The general public as well as emergency care providers needs to be aware of this dangerous emerging threat while in the throes of the fentanyl epidemic.  Medical providers need the tools - readily available rapid tests for xylazine, for example - to evaluate and treat these potentially more complex opioid overdose patients.

Dan Mazanec, MD, FACP

1/9/2024






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