Xylazine (also known as “tranq”) is a potent
nonopioid
veterinary sedative that has recently experienced a surge in use as
a drug adulterant, most often combined with illicitly manufactured
fentanyl. This combination may heighten the risk of fatal overdose.
Xylazine has no known antidote approved for use in humans, and age-adjusted
overdose deaths involving xylazine were 35 times higher in 2021 than
2018. In April 2023, the Biden Administration declared xylazine-laced
fentanyl an emerging drug threat in the United States. In 2022, the
Drug Enforcement Agency (DEA) reported nearly a quarter of seized
fentanyl powder contained xylazine. This dramatic increase in prevalence
has solidified the status of xylazine as an emerging drug of abuse
and an evolving threat to public health. The following narrative review
outlines the synthesis, pharmacokinetics, pharmacodynamics, and adverse
effects of xylazine, as well as the role it may play in the ongoing
opioid epidemic.