Emergency department-based testing for xylazine and other novel psychoactive substances in Central Alabama: a feasibility study.

Alabama, like other states in the Deep South, lacks comprehensive testing for novel psychoactive substances (NPS) and adulterants like xylazine, leaving gaps in the detection of drug supply changes. From August 2024 to July 2025, we implemented an active testing approach at an emergency department (ED) in central Alabama among people with active illicit fentanyl use. Testing residual biological specimens collected as part of health care offers a potentially useful window into the prevalence of NPS in the drug supply, particularly in communities where traditional drug checking services might be impermissible or difficult to resource. In this study, we used liquid chromatography-quadrupole time of flight mass spectrometry (LC-QTOF-MS) to test the participants' residual biological specimens (blood, urine) coupled with a survey focused on demographics and drug use. We enrolled 37 participants who completed surveys, and 31 who completed LC-QTOF-MS testing. 84% of participants were white (n = 31), 51.4% were male (n = 19), 54.1% were homeless (n = 20), and 45.9% resided in rural areas (n = 17). In participants with comprehensive toxicology testing (n = 31, 83.8%), we detected xylazine in 25 (80.6%). We identified the first confirmed case of medetomidine exposure in the state of Alabama. We also identified a high proportion of samples with the NPS o-methylfentanyl (n = 9, 29.0%), the first published identification of this substance in the region to our knowledge. Among participants with toxicology testing, 59.3% (n = 16) had previously heard of xylazine and 41.9% (n = 13) had knowingly used it in the past. This pilot study demonstrated the feasibility and practical utility of ED-based residual biological specimen illicit drug surveillance. This approach has the potential to identify new emerging substances in the unregulated drug supply.