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Medetomidine
Chemical compound From Wikipedia, the free encyclopedia
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Medetomidine is a veterinary anesthetic medication with potent sedative effects and emerging illicit drug adulterant.[4]
It is a racemic mixture of two stereoisomers, levomedetomidine and dexmedetomidine, the latter being the isomer with the pharmacologic effect as an alpha 2- adrenergic agonist. Effects can be reversed using atipamezole.
It was developed by Orion Pharma.[5] It is approved for dogs in the United States, and distributed in the United States by Pfizer Animal Health and by Novartis Animal Health in Canada under the product name Domitor. Starting in 2022 medetomidine has been detected in the US in samples of illicit drugs and associated with overdoses.
The free base form of medetomidine is sold as an antifouling substance for marine paints.[6]
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History
Medetomidine was developed by Orion Pharma and launched in 2007.[5]
Pharmacology
Medetomidine is a racemic mixture of two optical or stereoisomers, levomedetomidine and dexmedetomidine.[7] The latter causes the alpha 2- adrenergic agonist effects.[8]
Medetomidine is an α2-adrenergic receptor agonist that binds at a ratio of 1620:1 with imidazoline receptor activity.[9]
Medetomidine is metabolised in the liver via hydroxylation.[9]
Veterinary use
Medetomidine has supplanted xylazine as a sedative for cats and dogs in several countries. Medetomidine is used off-label in horses.[9]
Atipamezole, an a2 adrenergic antagonist, was developed specifically as a reversal agent for medetomidine.[9]
Side effects
Following administration, marked peripheral vasoconstriction and bradycardia are noted.[10]
Medetomidine administration in sheep activates pulmonary macrophages that damage the capillary endothelium and alveolar type I cells. This in turns causes alveolar haemorrhage and oedema causing hypoxaemia.[9][11][12]
Use in marine paint
The free base form of medetomidine is sold as Selektope as an antifouling substance in marine paints.[6] It is mainly effective against barnacles, as shown in vitro with Balanus improvisus.[13] It has also shown effect on other hard fouling like tube worms. When the barnacle cyprid larva encounters a surface containing medetomidine the molecule interacts with the octopamine receptor in the larva. This causes the settling larva to increase its kicking to more than 100 kicks per minute, which makes becoming sessile nearly impossible.[14] 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]
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Illicit use in humans
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Component of street drugs
Medetomidine has been found as a component in street drug mixtures in the US starting in 2022,[7][4] containing synthetic opioids in a similar manner as xylazine-fentanyl, such mixtures have been nicknamed "tranq" (short for tranquilizer). 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.[15][16][17][18][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[19] and Pittsburgh, PA. Cases of overdose in Chicago from medetomidine/fentanyl mixtures have been reported In May, 2024.[20] Massachusetts reported its first cases in August 2024.[21]
Medetomidine does not respond to naloxone, complicating the medical response to overdoses. During summer 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. One researcher compared experimenting with the current drug supply to "playing Russian roulette".[22]
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References
Further reading
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