Isomeric Determination of Medetomidine in Street Drug Samples (August 2024 – February 2025) and Implications for Immunoassay Test Strip Analysis

Over the last several years there has been an influx of α2-agonists into the street drug supply. This began with the proliferation of xylazine, a potent veterinary sedative. Since 2023, another sedative, medetomidine, has been widely detected. Medetomidine, broadly, encompasses two optical isomers – dexmedetomidine and levomedetomidine – with the dex- isomer being pharmacologically active and used in licit human formulations. In this work, we investigate street drug samples containing medetomidine to better understand their isomeric makeup in the illicit supply. Liquid chromatography tandem mass spectrometry (LC-MS/MS) was used to analyze 100 drug product or paraphernalia residue samples. All samples were found to contain a racemic mixture of medetomidine. A subset of samples were analyzed by medetomidine immunoassay test strips, where racemic mixtures were not found to negatively affect results. All samples were also qualitatively analyzed using direct analysis in real time mass spectrometry (DART-MS) to identify commonly co-occurring compounds, which included fentanyl, xylazine, and local anesthetics. Parabens, preservatives found in licit injectable preparations of the drug, were not detected. This work provides a snapshot into the medetomidine makeup of street drug supply, which needs to be continually monitored given the differences in pharmacology between the two optical isomers.