It was developed byOrion Pharma.[6] It is approved for dogs in the United States, and distributed in the United States byPfizer Animal Health and byNovartis Animal Health in Canada under the product nameDomitor. Starting in 2022 medetomidine has been detected in the US in samples of illicit drugs and associated with overdoses.
Medetomidine has supplantedxylazine as a sedative for cats and dogs in several countries. Medetomidine is usedoff-label in horses.[10] Medetomidine is highly selective for the α2-adrenergic receptor with it being 1000 times more selective for α2 versus α1 than xylazine is.[11]
Medetomidine lasts for half an hour to three hours, with higher doses having a longer effect. Medetomidine is used for short procedures and is often combined withketamine or an opioid such asbutorphanol.[11]
Medetomidine administration in sheep activates pulmonary macrophages that damage thecapillary endothelium andalveolar type I cells. This in turns causes alveolar haemorrhage and oedema causing hypoxaemia.[10][13][14]
The free base form of medetomidine is sold asSelektope as anantifouling substance in marine paints.[7] It is mainly effective againstbarnacles, as shownin vitro withBalanus improvisus.[15] It has also shown effect on other hard fouling liketube worms. When the barnaclecyprid larva encounters a surface containing medetomidine the molecule interacts with theoctopamine receptor in the larva. This causes the settling larva to increase its kicking to more than 100 kicks per minute, which makes becomingsessile nearly impossible.[16] When the larva swims away from the surface, the effect disappears (reversible effect). The larva regains its pre-exposure function and can settle somewhere else.[citation needed]
Medetomidine has been found as a component in street drug mixtures in the US starting in 2022,[8][4] containing synthetic opioids in a similar manner asxylazine-fentanyl, such mixtures have been nicknamed "tranq" (short for tranquilizer); medetomidine on its own has been nicknamed "rhino tranq".[17] The combination of α2 adrenergic agonists with opioids are believed to greatly increase the sedative effects of each drug, which some drug users may perceive as a better or more potent product. The Center for Forensic Science Research and Education (CFSRE) first identified a synthetic opioid blend containing fentanyl and medetomidine sold in Maryland in July, 2022. Additional detections in late 2023 found similar medetomidine mixtures in Missouri, Colorado, Pennsylvania, California, and Maryland found in both drug material and the blood of patients experiencing overdoses.[18][19][20][21][4]
In January 2024 drug mixtures containing medetomidine were identified in the Canadian city of Toronto, ON. In April, 2024 and May, 2024 medetomidine was found in a mixture containing fentanyl and xylazine in Philadelphia, PA[22] and Pittsburgh, PA. Cases of overdose in Chicago from medetomidine/fentanyl mixtures have been reported in May, 2024.[23] Massachusetts reported its first cases in August 2024.[24]
In the summer of 2024, there were "mass overdose events" linked to medetomidine adulterated drugs in Chicago and Philadelphia. Emergency room doctors in Philadelphia reported waves of overdose patients coming in with unusually low heart rates. Public health advisories were issued. Experts warned that it was not business as usual for first responders, emergency room personnel or drug users.[17] One researcher compared experimenting with the current drug supply to "playing Russian roulette".[25]
^abcdeLamont LA, Creighton CM (11 September 2024). "Sedatives and Tranquilizers". In Lamont L, Grimm K, Robertson S, Love L, Schroeder C (eds.).Veterinary Anesthesia and Analgesia, The 6th Edition of Lumb and Jones. Wiley Blackwell. pp. 338–344.ISBN978-1-119-83027-6.
^abPapich M (2016).Saunders Handbook of Veterinary Drugs (4th ed.). Elsevier.ISBN978-0-323-24485-5.
^"Domitor".Novartis Animal Health Canada. 2003. Archived fromthe original on 2007-09-24.
^Celly CS, Atwal OS, McDonell WN, Black WD (February 1999). "Histopathologic alterations induced in the lungs of sheep by use of alpha2-adrenergic receptor agonists".American Journal of Veterinary Research.60 (2). Am J Vet Res:154–161.doi:10.2460/ajvr.1999.60.02.154.PMID10048544.
^Celly CS, McDonell WN, Young SS, Black WD (December 1997). "The comparative hypoxaemic effect of four alpha 2 adrenoceptor agonists (xylazine, romifidine, detomidine and medetomidine) in sheep".Journal of Veterinary Pharmacology and Therapeutics.20 (6):464–471.doi:10.1046/j.1365-2885.1997.00097.x.PMID9430770.
^Dahlström M, Mårtensson LG, Jonsson PR, Arnebrant T, Elwing H (November 2000). "Surface active adrenoceptor compounds prevent the settlement of cyprid larvae of Balanus improvisus".Biofouling.16 (2–4):191–203.Bibcode:2000Biofo..16..191D.doi:10.1080/08927010009378444.S2CID85603381.
