Medetomidine is a veterinary

anesthetic An anesthetic (American English) or anaesthetic (British English; see spelling differences) is a drug used to induce anesthesia ⁠— ⁠in other words, to result in a temporary loss of sensation or awareness. They may be divided into t ...

drug with potent

sedative A sedative or tranquilliser is a substance that induces sedation by reducing irritability or Psychomotor agitation, excitement. They are central nervous system (CNS) Depressant, depressants and interact with brain activity, causing its decelera ...

effects and emerging illicit drug

adulterant An adulterant is a substance secretly added to another that may compromise the safety or effectiveness. Typical substances that are adulterated include food, cosmetics, pharmaceuticals or fuels. Definition Adulteration is the practice of secre ...

. It is a

racemic mixture In chemistry, a racemic mixture or racemate () is a mixture that has equal amounts (50:50) of left- and right-handed enantiomers of a chiral molecule or salt. Racemic mixtures are rare in nature, but many compounds are produced industrially as r ...

of two

stereoisomer In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in ...

s, 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. It is approved for dogs in the United States, and distributed in the United States by

Pfizer Pfizer Inc. ( ) is an American Multinational corporation, multinational Pharmaceutical industry, pharmaceutical and biotechnology corporation headquartered at The Spiral (New York City), The Spiral in Manhattan, New York City. Founded in 184 ...

Animal Health and by

Novartis Novartis AG is a Swiss multinational corporation, multinational pharmaceutical company, pharmaceutical corporation based in Basel, Switzerland. Novartis is one of the largest pharmaceutical companies in the world and was the eighth largest by re ...

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.

History

Medetomidine was developed by Orion Pharma and launched in 2007.

Pharmacology

Medetomidine is a

of two optical or

s, levomedetomidine and dexmedetomidine. The latter causes the alpha 2- adrenergic agonist effects. It is often used as the hydrochloride salt, medetomidine hydrochloride, a crystalline white solid that can be administered as an intravenous drug solution with sterile water.

Veterinary use

veterinary anesthesia Veterinary anesthesia is a specialization in the veterinary medicine field dedicated to the proper administration of anesthetic agents to non-human animals to control their consciousness during procedures. A veterinarian or a Registered Veterinary T ...

, medetomidine is used as both a surgical and

analgesic An analgesic drug, also called simply an analgesic, antalgic, pain reliever, or painkiller, is any member of the group of drugs used for pain management. Analgesics are conceptually distinct from anesthetics, which temporarily reduce, and in s ...

in combinations with opioids ( butorphanol, buprenorphine etc.) as premedication (before a

general anesthetic General anaesthetics (or anesthetics) are often defined as compounds that induce a loss of consciousness in humans or loss of righting reflex in animals. Clinical definitions are also extended to include an induced coma that causes lack of aware ...

) in healthy cats and dogs. It is sometimes used in combination with butorphanol and

ketamine Ketamine is a cyclohexanone-derived general anesthetic and NMDA receptor antagonist with analgesic and hallucinogenic properties, used medically for anesthesia, depression, and pain management. Ketamine exists as its S- (esketamine) a ...

(given IM) to produce general anaesthesia for short periods in healthy, but fractious felines, that will not allow an intravenous induction agent to be given providing a good degree of muscle relaxation. It has also been used in combination with

morphine Morphine, formerly also called morphia, is an opiate that is found naturally in opium, a dark brown resin produced by drying the latex of opium poppies (''Papaver somniferum''). It is mainly used as an analgesic (pain medication). There are ...

(or

methadone Methadone, sold under the brand names Dolophine and Methadose among others, is a synthetic opioid used medically to treat chronic pain and opioid use disorder. Prescribed for daily use, the medicine relieves cravings and opioid withdrawal sym ...

lidocaine Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia and ventricular fibrillation. When used for local anae ...

and ketamine in constant rate infusion analgesia in canines. It is often used in so called microdoses for this analgesic effect. It is thought that this family of drugs has a degree of analgesic action, though this is, in comparison to the

effect, minor. It can be given by

intramuscular injection Intramuscular injection, often abbreviated IM, is the medical injection, injection of a substance into a muscle. In medicine, it is one of several methods for parenteral, parenteral administration of medications. Intramuscular injection may be ...

(IM),

subcutaneous injection Subcutaneous administration is the insertion of medications beneath the skin either by injection or infusion. A subcutaneous injection is administered as a bolus (medicine), bolus into the subcutis, the layer of skin directly below the dermis and ...

(SC) or

intravenous injection Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutr ...

(IV). When delivered intravenously, a significantly decreased dose is used. Some authors suggest a

sublingual Sublingual (List of abbreviations used in medical prescriptions, abbreviated SL), from the Latin for "under the tongue", refers to the pharmacological route of administration by which substances diffuse into the blood through Tissue (biology), t ...

route is also effective. It is not recommended for diabetics and is contraindicated in patients with cardiac disease. Due to its potent sedative effects it is commonly used in more aggressive animals, where a drug combination with a lesser effect (such as acepromazine plus an

opioid Opioids are a class of Drug, drugs that derive from, or mimic, natural substances found in the Papaver somniferum, opium poppy plant. Opioids work on opioid receptors in the brain and other organs to produce a variety of morphine-like effects, ...

, or an opioid plus a

benzodiazepine Benzodiazepines (BZD, BDZ, BZs), colloquially known as "benzos", are a class of central nervous system (CNS) depressant, depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed t ...

) would not allow the administration of the inductive agent without risk to the veterinarian. As such the use of alpha-two agonists is only recommended in healthy animals.

Side effects

Following administration, marked peripheral

vasoconstriction Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vesse ...

and

bradycardia Bradycardia, also called bradyarrhythmia, is a resting heart rate under 60 beats per minute (BPM). While bradycardia can result from various pathological processes, it is commonly a physiological response to cardiovascular conditioning or due ...

are noted. Often the dosage of induction agents (e.g.

propofol Propofol is the active component of an intravenous anesthetic formulation used for induction and maintenance of general anesthesia. It is chemically termed 2,6-diisopropylphenol. The formulation was approved under the brand name Diprivan. Nu ...

) may be drastically reduced, as may the volumes of anesthetic gases (i.e.

halothane Halothane, sold under the brand name Fluothane among others, is a general anaesthetic. It can be used to induce or maintain anaesthesia. One of its benefits is that it does not increase the production of saliva, which can be particularly useful ...

isoflurane Isoflurane, sold under the brand name Forane among others, is a halogenated ether used as a general anesthetic. It can be used to start or maintain anesthesia; however, other medications are often used to start anesthesia, due to airway irritat ...

sevoflurane Sevoflurane, sold under the brand name Sevorane, among others, is a sweet-smelling, nonflammable, highly fluorinated methyl isopropyl ether used as an inhalational anaesthetic for induction and maintenance of general anesthesia. After desflu ...

) used to maintain general anesthesia. Its effects can be reversed using atipamezole distributed as Antisedan by Pfizer. IV use of atipamezole is not licensed, IM is the preferred route.

Yohimbine Yohimbine, also known as quebrachine, is an indole alkaloid derived from the bark of the African tree '' Pausinystalia johimbe'' (yohimbe); also from the bark of the unrelated South American tree '' Aspidosperma quebracho-blanco''. Yohimbine is ...

may also be used in an emergency situation, but is not licensed.

Use in marine paint

The free base form of medetomidine is sold as Selektope as an

antifouling Biofouling or biological fouling is the accumulation of microorganisms, plants, algae, or small animals where it is not wanted on surfaces such as ship and submarine hulls, devices such as water inlets, pipework, grates, ponds, and rivers that ...

substance in marine paints. It is mainly effective against

barnacles Barnacles are arthropods of the subclass Cirripedia in the subphylum Crustacea. They are related to crabs and lobsters, with similar nauplius larvae. Barnacles are exclusively marine invertebrates; many species live in shallow and tidal water ...

, as shown in vitro with Balanus improvisus. 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. 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.

Illicit use in humans

Component of street drugs

Medetomidine has been found as a component in street drug mixtures in the US starting in 2022, containing synthetic opioids in a similar manner as

xylazine Xylazine is a structural analog of clonidine and an α2-adrenergic receptor, α2-adrenergic receptor agonist, sold under many trade names worldwide, most notably the Bayer brand name Rompun, as well as Anased, Sedazine and Chanazine. Xylazine ...

fentanyl Fentanyl is a highly potent synthetic piperidine opioid primarily used as an analgesic (pain medication). It is 30 to 50 times more Potency (pharmacology), potent than heroin and 50 to 100 times more potent than morphine. Its primary Medici ...

, 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. 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 and Pittsburgh, PA. Cases of overdose in Chicago from medetomidine/fentanyl mixtures have been reported In May, 2024. Massachusetts reported its first cases in August 2024. Medetomidine does not respond to

naloxone Naloxone, sold under the brand name Narcan among others, is an opioid antagonist, a medication used to reverse or reduce the effects of opioids. For example, it is used to restore breathing after an opioid overdose. Effects begin within two ...

, 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".

Other criminal use

Medetomidine was found in combination with the mu-opioid antagonist and kappa-opioid agonist Butorphanol and sedative dopamine antagonist tranquilizer

Azaperone Azaperone is a pyridinylpiperazine and butyrophenone neuroleptic drug with sedative and antiemetic effects, which is used mainly as a tranquilizer in veterinary medicine. It is uncommonly used in humans as an antipsychotic drug. Azaperone acts ...

in the blood of a 49-year old female homicide victim from Colorado that went missing after a bike ride in 2020. Such a mixture wouldn't be used for recreational use and would instead likely produce

dysphoria Dysphoria (; ) is a profound state of unease or dissatisfaction. It is the semantic opposite of euphoria. In a psychiatric context, dysphoria may accompany depression, anxiety, or agitation. In psychiatry Intense states of distress and uneas ...

with heavy sedative effects that may render a person immobile or unable to defend themselves.