Qualitative and quantitative determination of xylazine in oral fluid.

This article focuses on the development and validation of methods for detecting and quantifying xylazine, a veterinary sedative increasingly found as an adulterant in illicit fentanyl use, in oral fluid (OF) samples. Using enzyme-linked immunosorbent assay (ELISA) for rapid screening and solid-phase extraction (SPE) coupled with liquid chromatography–tandem mass spectrometry (LC–MS–MS) for confirmation, the methods demonstrated high accuracy, precision, and robustness according to American National Standards Institute/American Academy of Forensic Sciences Standards Board (ANSI/ASB) Standard 036. Analysis of 57 OF samples from substance use disorder and therapeutic drug monitoring clinics revealed xylazine concentrations ranging from 1.2 to 23.3 ng/mL. The study highlights OF testing as a noninvasive, efficient tool for toxicological surveillance of xylazine amid its rising public health impact in opioid-related overdoses.