Medetomidine in the unregulated drug supply

E10191 Medetomidine is a common adulterant in the opioid supply in North America An α-2 adrenergic agonist approved only for veterinary use, medetomidine is similar to xylazine, but substantially more potent. 1Medetomidine is increasingly present in the unregulat ed drug supply, found in 85% of all opioid samples recently tested in Toronto, Canada. 2 2 Medetomidine should be suspected when patients present with features of opioid intoxication but do not respond to naloxone Patients may present with features of opioid overdose, along with prolonged sedation, and profound sinus bradycardia. 1,3Medetomidine intoxication cannot be reversed, 1 although naloxone should be administered to treat the opioid component of an overdose. Patients who abruptly discontinue use of unregulated opioids are at risk of medetomidine withdrawalSigns and symptoms can include hypertension, tachycardia, tremors, diaphoresis, hyperthermia, and intractable nausea and vomiting, with onset as soon as 4 to 6 hours after discontinuing use. 3,4Medetomidine withdrawal can cause QTc prolongation and metabolic derangements, including hypokalemia.