Xylazine, also known as tranq, is often mixed with another already dangerous drug—fentanyl.
“Fentanyl is an opiate—a very powerful opiate—that is being made in other countries
and transported to the United States,” McDonald said.
Adding xylazine to a batch of fentanyl increases the bulk of the product available
to sell—the greater the bulk, the greater the profit.
“It is a veterinary anesthesia—not approved for human use,” McDonald explained. “Veterinary
drugs are a softer target. They are not as regulated and it is perhaps easier to get
them than to rob a CVS.”
Like other opiates, xylazine acts as an anesthetic but it has a different mechanism
of action.
“It has similar effects,” McDonald said. “It decreases blood pressure, slows heart
rates producing bradycardia, and causes respiratory depression and drowsiness.”
This can lead to the zombie-like behaviors of tranq users depicted in videos recorded
in the Kensington neighborhood of Philadelphia. While those videos have dominated
media coverage, the same effects can occur with any opiate according to McDonald.
“Fentanyl, heroin and other opiates can do that, but when you combine it with xylazine,
it has an additive effect,” he said. “The behaviors we unfortunately see in these
vulnerable populations are usually a combination of these different illicit substances.”
The lack of quality control in the manufacturing of illicit drugs creates a dangerous
situation in which the concentration of xylazine may vary from supplier to supplier,
McDonald added. Users may find the effect they get from drugs acquired from one supplier
may differ from another and, as a result, may tend to gravitate back to a particular
supplier or location in an effort to replicate the high.
“It’s hard to predict the effects of these illicit drugs, that’s why they are so deadly,”
he said.
Additionally, unlike other opiates, the effects of xylazine are harder to counteract.
“Things like NARCAN® (naloxone) can reverse the effects of opiates like fentanyl but it will not have
an effect on xylazine,” McDonald explained. “Some medications in the veterinary field
can reverse the effects of xylazine but they are not approved for human use.”
As a result, a xylazine overdose is not easily treated and can be fatal. When a drug
fatality occurs, it is up to professionals like McDonald to determine if xylazine
was a factor in the death.