Medetomidine and Other Veterinary Medicines Found in Seized Drug Samples

"Medetomidine, a veterinary non-selective alpha-2-agonist like xylazine, has also been gaining recognition as an adulterant across the recreational opioid drug supply in the US. It is yet to be identified in the UK illicit supply (as of July 2024), yet it has been reported to be rapidly proliferating across the USA and Canada in samples also containing heroin, fentanyl, xylazine, and cocaine [11,12]. Medetomidine’s increasing prevalence is concerning due to it being a more potent, selective, and specific a-2-agonist, exhibiting increased sedation compared with xylazine [13]. Alongside medetomidine, two other veterinary medications—acepromazine (a phenothiazine) and phenylbutazone (a non-steroidal anti-inflammatory drug (NSAID))—were identified as potential toxic adulterants and predicted to be the “next xylazine” [14]. Although acepromazine reports remain relatively low, phenylbutazone has been identified in 116 seized drug samples between 2016 and 2021, alongside heroin, fentanyl, xylazine, tramadol, and cocaine [15]. Pentobarbital, a veterinary euthanasia agent, has also been detected in seized samples across the US [15,16], although it is classified as a Class B Schedule 3 drug. These five drugs’ pharmacological profiles have made them valuable tools in veterinary medicine, yet it is these same properties that influence the dangerous outcomes in humans. The lack of control or scheduling of these drugs may contribute to their increased availability and prevalence, leading to their rise as adulterants in the illicit opioid supply."