Xylazine: A Drug Adulterant of Clinical Concern

Purpose of review: The opioid epidemic has been responsible for significant morbidity and mortality in the USA and worldwide. As a result, it is essential to recognize the threat these potent drugs can cause when illicitly used. Specifically, introducing fentanyl as a drug adulterant has been shown to impact overdose rates drastically. In this regard, the Drug Enforcement Agency recently released a public safety alert announcing the new threat of a new adulterant called xylazine. Xylazine is a powerful animal sedative with a different mechanism of action when compared to illicit opioids such as heroin and fentanyl. Xylazine is typically injected intravenously via a syringe, often in combination with multiple other drugs. One of the most common drugs, xylazine, is taken in combination with fentanyl, with users of this drug combination describing xylazine as prolonging the euphoric sensation produced by fentanyl.

Recent findings: Xylazine may cause adverse effects such as bradycardia, brief hypertension followed by hypotension, premature ventricular contractions, ataxia, slurred speech, sedation, and respiratory depression. Much of the recent literature on xylazine use in humans comes from case reports and review articles. Related to widespread use in veterinary medicine and increasing circulation in illicit drug markets, there is a critical need for public awareness and additional clinical-based studies to further increase understanding of mediated or modulated pharmacological effects of xylazine in humans. Further research is urgently needed to more clearly understand the implications of unregulated xylazine in the illicit drug market, to formulate public health interventions, and to implement harm reduction strategies.