Detomidine

Detomidine is an imidazole derivative and α2-adrenergic agonist, used as a large animal sedative, primarily used in horses. It is usually available as the salt detomidine hydrochloride. It is a prescription medication available to veterinarians sold under the trade name Dormosedan.

Detomidine
Clinical data
AHFS/Drugs.comInternational Drug Names
ATCvet code
Legal status
Legal status
  • Veterinary use only
Pharmacokinetic data
Elimination half-life30 min
Identifiers
CAS Number
PubChem CID
ChemSpider
UNII
KEGG
ChEMBL
CompTox Dashboard (EPA)
Chemical and physical data
FormulaC12H14N2
Molar mass186.258 g·mol−1
3D model (JSmol)
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Currently, detomidine is only licensed for use in horses in the US but it is also licensed for use in cattle in Europe and Australasia.[1]

Properties

Detomidine is a sedative with analgesic properties.[2] α2-adrenergic agonists produce dose-dependent sedative and analgesic effects, mediated by activation of α2 catecholamine receptors, thus inducing a negative feedback response, reducing production of excitatory neurotransmitters. Due to inhibition of the sympathetic nervous system, detomidine also has cardiac and respiratory effects and an antidiuretic action.[3]

Effects

A profound lethargy and characteristic lowering of the head with reduced sensitivity to environmental stimuli (sound, pain, etc.) are seen with detomidine. A short period of reduced coordination is characteristically followed by immobility and a firm stance with front legs spread. Following administration there is an initial increase in blood pressure, followed by bradycardia and second degree atrioventricular block (this is not pathologic in horses). The horse commonly sweats to excess, especially on the flanks and neck. Other side effects reported include pilo erection (hair standing erect), ataxia, salivation, slight muscle tremors, and (rarely) penile prolapse.

Uses

Sedation and anaesthetic premedication in horses and other large animals, commonly combined with butorphanol for increased analgesia and depth of sedation. In conjunction with ketamine it may also be used for intravenous anaesthesia of short duration.

The drug is normally administered by the intravenous route, and is fastest and most efficient when given intravenously . However, in recalcitrant animals, detomidine may be administered by the intramuscular or sublingual routes. The dose range advised by the manufacturers is 20–40 µg/kg intravenous for moderate sedation, but this dose may need to be higher if given intramuscularly.

When given intravenously, detomidine usually takes effect in 2–5 minutes, and recovery is full within 30–60 minutes. However, this is highly dependent upon the dosage, environment, and the individual animal; some horses are highly resistant to sedation.

Cautions

As detomidine is an arrhythmogenic agent, extreme care should be exercised in horses with cardiac disease, and in the concurrent administration of other arrhythmogenics. The concurrent use of potentiated sulfonamide antibiotics is considered particularly dangerous.

Detomidine is a poor premedication when using ketamine as an anesthetic in horses.

Anesthetic recoveries in horses that have received ketamine following a detomidine premedication are often violent with the horse having multiple failures to stand resulting in trauma to itself. Xylazine is a superior premedication with ketamine resulting in safer recoveries.

See also

References
  1. Clarke, Kathy W.; Hall, Leslie W.; Trim, Cynthia M., eds. (2014). "Principles of sedation, anticholinergic agents, and principles of premedication". Veterinary Anaesthesia. pp. 79–100. doi:10.1016/B978-0-7020-2793-2.00004-9. ISBN 978-0-7020-2793-2.
  2. England GC, Clarke KW (November 1996). "Alpha 2 adrenoceptor agonists in the horse--a review". The British Veterinary Journal. 152 (6): 641–57. doi:10.1016/S0007-1935(96)80118-7. PMID 8979422.CS1 maint: uses authors parameter (link)
  3. Fornai F, Blandizzi C, del Tacca M (1990). "Central alpha-2 adrenoceptors regulate central and peripheral functions". Pharmacological Research. 22 (5): 541–54. doi:10.1016/S1043-6618(05)80046-5. PMID 2177556.
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