May 2, 2025: Who is (another) new kid on the block that is being mixed in with illicit opioids?

May 2, 2025

Medetomidine is an adulterant that has been found increasingly in illicit opioids.

Medetomidine is used as a veterinary sedative and is essentially a racemic mixture of levomedetomidine and dexmedetomidine (Dex). Dex is primarily the active enantiomer and is used in humans. These are alpha 2 agonists and cause the same signs as Dex in humans-sedation, bradycardia, and hypotension (occasional short term hypertension early in the course). In 2023, testing of residual from suspected drug packaging and paraphernalia in Maryland demonstrated the presence of medetomidine in a small number of their monitoring of the drug supply.1

A 2024 MMWR described the detection of medetomidine in patients who were evaluated in emergency department settings for presumed opioid overdose. This detection occurred in the states of Colorado, Missouri, and Pennsylvania.2 This study tested blood samples obtained from emergency department patients with presumed opioid overdose from Sept 2020-2023. Five patients in 3 states had detection of medetomidine in their blood samples. Two patients were hypotensive but no bradycardia. Comprehensive testing also demonstrated fentanyl in three patients, stimulants in three, xylazine in three, and nitazene opioids in two.

The most recent report in MMWR involved an outbreak in May 2024 in Chicago. There was a sudden uptick in the number of emergency medicine services responses for suspected opioid overdoses. The investigation identified 12 confirmed, 26 probably and 140 suspected overdoses of medetomidine with the opioids over the course of about a week.3

Of the 38 confirmed and probably cases, 95% had hypertension, 87% had bradycardia, 84% altered mental status and 84% had pinpoint pupils. Of the 12 patients with confirmed exposure to medetomidine, 11 patients had little to no response to naloxone administration. Testing of samples from bagged powders from five patients detected medetomidine mixed with fentanyl.

  1. Sisco E. Appley M. Identification of the veterinary sedative medetomidine in combination with opioids and xylazine in Maryland. J Forensic Sci 2023;68:1708-12.
  2. Schwarz ES, Buchanan J, Aldy K, et al. Notes from the field: detection of medetomidine among patients evaluated in emergency departments for suspected opioid overdoses-Missouri, Colorado, and Pennsylvania. MMWR 2024;73:672-4.
  3. Nham A, Le, JN, Thomas SA, et al. Overdoses involving medetomidine mixed with opioids-Chicago, Illinois, May 2024. MMWR 2025;74:258-65.