Medetomidine is a synthetic drug used as both a surgical anesthetic and

analgesic An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of drugs used to achieve relief from pain (that is, analgesia or pain management). It ...

. It is often used as the hydrochloride salt, medetomidine hydrochloride, a crystalline white solid. It is an α2 adrenergic agonist that can be administered as an intravenous drug solution with sterile water. It was developed by

Orion Pharma Orion Corporation ( fi, Orion Oyj), founded in 1917 and headquartered at Espoo, Finland, is a globally operating Finnish company which develops, manufactures and markets human and veterinary Pharmaceutical company, pharmaceuticals and Active ing ...

. 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. Other alpha-two agonists used in veterinary medicine include xylazine and detomidine, but their use is less common in small animal surgery. The marketed product is a

racemic mixture In chemistry, a racemic mixture, or racemate (), is one that has equal amounts 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 racemates. ...

of two stereoisomers; dexmedetomidine is the isomer with more useful effects, and is now marketed as Dexdomitor. The free base form of medetomidine is sold as Selektope for use as an antifouling substance in marine paints.

Veterinary use

In veterinary anesthesia, medetomidine is often used in combinations with opioids ( butorphanol, buprenorphine etc.) as premedication (before a general anesthetic) in healthy cats and dogs. It can be given by

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

(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 into the subcutis, the layer of skin directly below the dermis and epidermis, ...

(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 nutri ...

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

sublingual Sublingual (abbreviated SL), from the Latin for "under the tongue", refers to the pharmacological route of administration by which substances diffuse into the blood through tissues under the tongue. The sublingual glands receive their prima ...

route is also effective. It is not recommended for diabetics, it 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, or an opioid plus a

benzodiazepine Benzodiazepines (BZD, BDZ, BZs), sometimes called "benzos", are a class of depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed to treat conditions such as anxiety disorders, ...

) 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. Following administration, marked peripheral vasoconstriction and

bradycardia Bradycardia (also sinus bradycardia) is a slow resting heart rate, commonly under 60 beats per minute (BPM) as determined by an electrocardiogram. It is considered to be a normal heart rate during sleep, in young and healthy or elderly adults, a ...

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

propofol Propofol, marketed as Diprivan, among other names, is a short-acting medication that results in a decreased level of consciousness and a lack of memory for events. Its uses include the starting and maintenance of general anesthesia, sedation f ...

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

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

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 desfluran ...

) used to maintain general anesthesia. It is sometimes used in combination with butorphanol and ketamine (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. It provides a good degree of muscle relaxation, an important factor in ketamine based anesthesia protocols. Medetomidine has also been used in combination with morphine (or methadone),

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. When used for local anaesthesia or in nerve blocks, lidoca ...

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

Use in marine paint

Medetomidine can be used 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 t ...

substance in marine paint. It is mainly effective against barnacles, but 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 Octopamine (molecular formula C8H11NO2; also known as OA, and also norsynephrine, ''para''-octopamine and others) is an organic chemical closely related to norepinephrine, and synthesized biologically by a homologous pathway. Octopamine is ofte ...

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.

Veterinary use

Use in marine paint

References

Further reading