Trends in Tranq: Prevalence of Xylazine in Oral Fluid Toxicology in Michigan, Ohio, and Indiana

Background Xylazine (which goes by the street name “Tranq”) is a veterinary animal tranquilizer that is commonly and sometimes unknowingly used in combination with illicit fentanyl and has garnered increased media and government attention in recent months. The White House National Response Plan from July 2023 emphasized increased testing for xylazine as a crucial first step to curbing abuse. Forensic Fluids Laboratories (FFL), which specializes in oral fluid drug testing, began surveilling this substance beginning in early 2023. Here, we examined our data from over a year of testing and present our observations and trends we identified from this data. We show that oral fluid is an excellent tool for identifying xylazine use. Methods From March 2023 through March 2024, over 55,000 oral fluid specimens were analyzed using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS-MS) following a presumptive positive screen for methamphetamine, cocaine, opiates, fentanyl, and/or xylazine using FDA-approved Enzyme Linked Immunosorbent Assays (ELISA). Results of these analyses as well as associated geospatial metadata were extracted from the sample database and analyzed using Pandas and NumPy libraries in Python. Plots and maps were generated using Matplotlib and GeoPandas libraries in Python. Results On average over the entire testing period, xylazine was found in 3.41% of the total 55,691 analyzed samples. Using the three-month xylazine positivity rate, prevalence peaked at 3.76% of analyzed samples in June 2023 and hit its low in September 2023 at 3.14%. Of the xylazine-positive samples, fentanyl was present 96.5% of the time. In addition, 86.2% of xylazine samples indicated some degree of polydrug use where at least two other drug classes were present. Of note, stimulants and fentanyl were present in 61.4% of xylazine positives. Xylazine increased in prevalence among fentanyl-positive samples over time. Using the three-month average, xylazine was found in 21.70% of fentanyl-positive samples in May 2023 and was found in 30.92% in March 2024. Across the states of Michigan, Ohio, and Indiana, xylazine use spread to 45 new counties by the conclusion of our study window. At the county level, general xylazine hotspots were identified, and prevalence trends were variable with certain counties increasing and decreasing in xylazine use. Conclusions While the overall xylazine prevalence fluctuated among illicit recreational drug users from March 2023 through March 2024, the individual county-level trends during this time tended to reveal dynamic shifts in xylazine use. Our data highlights the spread of this drug across Michigan, Ohio, and Indiana, and provides support for increased xylazine adulteration of the illicit fentanyl drug supply. With these data trends, we aim to support local and state agencies in promoting continued action and collaboration toward mitigating spread of xylazine.