Qualitative and quantitative determination of xylazine in oral fluid.

Xylazine has emerged in recent years as a dangerous adulterant in illicit fentanyl use, and methods for the detection of xylazine in toxicology panels are still lagging. We developed methods for the screening and quantitation of xylazine in oral fluid (OF), a popular testing medium due to its ease of collection and reflection of presence in blood for many classes of drugs. Enzyme-linked immunosorbent assays were employed for the rapid screening of xylazine directly from the collection device buffer with a cutoff of 1 ng/mL. Solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry facilitated the confirmation and quantification of xylazine as low as 0.1 ng/mL and a dynamic range of 0.1-25 ng/mL. Selectivity, ionization suppression, processed sample stability, and dilution effect were also assessed. The method was validated through the American National Standards Institute/American Academy of Forensic Sciences Standards Board (ANSI/ASB) Standard 036, first edition from 2019, and found to be accurate, precise, and robust. Living human subject OF samples collected within substance use disorder and therapeutic drug monitoring clinics received between September 2023 and January 2024, with the specific request to test for xylazine (n = 57), were screened. Presumptive positive samples were confirmed using the validated method. Xylazine confirmed living human subject OF sample concentrations ranged from 1.2 to 23.3 ng/mL.

Direct-To-Definitive Urine and Oral Fluid Test Results for Unscreened and Rarely Screened Drugs in Individuals Applying for Methadone Treatment in 7 U.S. States.

The standard protocol in addiction treatment/pain management is to conduct immunoassay screens for major drugs subject to misuse, followed by confirmatory testing of positive results. However, this may miss unscreened or rarely screened drugs that could pose risks, especially to polydrug users. We sought to determine the prevalences of unscreened/rarely screened drugs in a sample of individuals misusing drugs in 7 U.S. states, and to compare the results of urine vs. oral testing for these drugs by direct-to-definitive liquid chromatography/tandem mass spectrometry (LC-MS-MS). The five drugs with the highest prevalences were: gabapentin (16.8%), quetiapine (6.2%), chlorpheniramine (5.3%), hydroxyzine (4.9%), and ephedrine (3.5%). All have clinical significance as indicated by severity of possible side effects, interactions with other drugs, and/or misuse potential. Drugs were generally detected more frequently in oral fluid than urine, but gabapentin was more frequently detected in urine. The prevalences of the included drugs seem high enough, and their clinical significance important enough, to warrant consideration of expanding clinical drug test panels, either by direct-to-definitive testing or the addition of selected immunoassay screens when available. Oral fluid was usually more suitable than urine as the test matrix, given the higher rates of detection in oral fluid for most substances included in this study.

Comparing presumptive with direct-to-definitive drug testing in oral fluid vs. urine for a U.S. national sample of individuals misusing drugs.

BACKGROUND: The aims are to compare the results of presumptive drug testing with confirmation of positives vs. direct-to-definitive drug testing, combined with investigation of urine vs. oral fluid as test matrices. METHODS: Paired oral fluid and urine specimens were collected voluntarily and anonymously from 1098 individuals applying for methadone treatment in 11 clinics across 7 U.S. states. All specimens were analyzed by immunoassay (IA) and liquid chromatography-tandem mass spectrometry (LC-MS-MS). RESULTS: Confirmed IA prevalences for urine were significantly higher than for oral fluid for 7 out of 10 drug classes - benzodiazepines, cannabis, cocaine, methadone, opiates, oxycodone and tramadol. Drug prevalences by direct-to-definitive LC-MS-MS were either the same or higher than prevalences by confirmed IA. Drug prevalences by LC-MS-MS were higher in urine for two drug classes (cocaine, methadone) and higher in oral fluid for two drug classes (buprenorphine, tramadol), but were equivalent in urine and oral fluid when averaged over all 10 drug classes. Certain drugs of special concern such as heroin and buprenorphine were more frequently detected in oral fluid than urine. CONCLUSIONS: Urine analysis showed some technical advantage over oral fluid in sensitivity to several drug classes within a confirmed IA testing protocol, but this may be outweighed if there is reason to believe that tampering with urine specimens is a significant problem. Overall drug detection by direct-to-definitive testing was similar for oral fluid and urine, but one matrix may be preferable if there is a particular drug of clinical or epidemiological interest.