By: Amy Racines, MS, Research & Development Senior Project Coordinator

The opioid crisis has affected the United States for more than a decade. In 2017, the United States declared the opioid crisis a public health emergency, and, since then, new drugs have emerged on the illicit market with fentanyl, xylazine, and, most recently, medetomidine¹. Medetomidine entered the illicit market in July 2022 and has been on the rise ever since, with public health alerts issued from late 2023 through 2024². It is almost always used in combination with opioids, and the user may not be aware of its presence.  

Medetomidine is a potent and short-acting sedative and analgesic medication. Medetomidine can exist as two isomers: dexmedetomidine or levomedetomidine. Dexmedetomidine was approved for use by the FDA in 1999, and it is currently being used for critically ill patients, during surgery, or for those on ventilators³. It is only available by prescription. Medetomidine can also exist as a racemic mixture of both isomers, levomedetomidine and dexmedetomidine. This form is only approved for use in veterinary medicine and is not approved for human consumption, yet it has entered the illicit market¹. 

Medetomidine is about 200 times more potent and 10 times more selective than xylazine, and its effects are longer-lasting^4,5. It binds to the alpha2-adrenoergic receptor just like xylazine. Medetomidine’s desired effects include sedation, muscle relaxation, analgesia, and anxiolysis⁶. However, the adverse effects of medetomidine are mainly respiratory and cardiovascular effects such as bradycardia and associated arrhythmias, hypertension or hypotension, and reduced cardiac output. NARCAN has no effect on a medetomidine overdose, though it should still be used due to medetomidine use often being concurrent with opioid use. The medication atipamezole reverses the sedative and cardiovascular effects of medetomidine in some animals, though it has never been studied in humans⁷. 

References:

1. Medetomidine Infiltrates the US Illicit Opioid Market 
2. Medetomidine_Public_Health_Alert__Final.pdf 
3. Use of dexmedetomidine in critical-ill patients: is it time to look to the actual evidence? | Critical Care | Full Text 
4. Scheinin, H., Virtanen, R., MacDonald, E., et al. Medetomidine—a novel alpha 2-adrenoceptor agonist: a review of its pharmacodynamic effects. Prog. Neuropsychopharmacol. Biol. Psychiatry. 13:635–651, 1989. [DOI] [PubMed] [Google Scholar] 
5. 9. Tyner, C.L., Woody, B.J., Reid, J.S., et al. Multicenter clinical comparison of sedative and analgesic effects of medetomidine and xylazine in dogs. J. Am. Vet. Med. Assoc. 211:1413–1417, 1997. [PubMed] [Google Scholar] 
6. A review of the physiological effects of α2-agonists related to the clinical use of medetomidine in small animal practice – PMC 
7. Sedative and cardiopulmonary effects of medetomidine hydrochloride and xylazine hydrochloride and their reversal with atipamezole hydrochloride in calves in: American Journal of Veterinary Research Volume 69 Issue 3 

 Learn more about Medetomidine Testing at USDTL.

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