Medetomidine hydrochloride
Applications in Veterinary Medicine and Wildlife Management
Medetomidine hydrochloride is a synthetic non-narcotic alpha-two adrenergic agonist with sedative and analgesic properties. Its antagonism by yohimbine, tolazoline and/or atipamezole makes it extremely valuable as a potent, versatile, highly effective reversible non-narcotic in non-domestic species in veterinary practice and wildife management.
General Information and History
Medetomidine and its analog detomidine were developed within the research arm of Farmos of Turku, Finland in the 1970s. Farmos was subsequently acquired by Orion of Helsinki. After commercialization in Scandinavia, medetomidine quickly found applications in non-domestic species. Dr. Harry Jalanka of the Helsinki Zoo conducted pioneering research in the use of medetomidine in zoo and free-ranging wildlife, laying the foundation for expansion into other species. Medetomidine was approved in the US in 1995 under the trade name of Domitor.
Use in Wildlife Management
Medetomidine is routinely used in combination with the dissociative ketamine. The combination of this potent alpha-two agonist and ketamine allows the immobilization of most non-domestic species, characterized by an animal that is very manageable and in a good state of analgesia.
Its high potency as an alpha-two agonist has made this drug useful in designing non-opiate combinations that can be used to capture free-ranging species. In the field, the use of medetomidine in combination with ketamine, butorphanol, and azaperone provides a reversible non-opiate combination that produces a satisfactory level of analgesia and muscle relaxation.
Medetomidine combined with ketamine has found new applications in cervids, large felids, mustelids, and bear in North America. Its high potency has allowed the capture of free-ranging wildife that were refractory to xylazine after being chased by vehicles or aircraft. Its concentration to 20 mg/ml has made it useful in dart delivery.
Use in Domestic Species
Medetomidine hydrochloride is routinely used in dogs.
Pharmacology and Chemistry
Medetomidine is more potent than xylazine and has a higher alpha-two agonist receptor affinity which produces sedation and analgesia. These effects are dose dependent in depth and duration. Medetomidine provides pharmacological restraint and pain relief to facilitate the handling of animals for diagnostic or therapeutic procedures, and minor surgical procedures. Spontaneous muscle contractions may be seen in some animals sedated with medetomidine.
Medetomidine hydrochloride chemically is -4-[1-(2,3-dimethylphenyl) ethyl] -1H-
imidazole monohydrochloride.
Pharmacokinetics
Blood pressure is initially increased due to peripheral vasoconstriction and then drops to normal or slightly lower than normal. Bradycardia can be prevented by IV administration of an anticholinergic agent.
CONTRAINDICATIONS AND PRECAUTIONS
Medetomidine hydrochloride should NOT be used in animals with the following conditions: cardiac disease, respiratory disorders, liver or kidney diseases; animals in shock, animals which are severely debilitated, or animals which are stressed due to extreme heat, cold or fatigue.
WARNING:
In non-domestic animals not responding satisfactorily to administration of Medetomidine hydrochloride, repeat dosing via dart is NOT recommended until after at least 30 minutes have passed.
ADVERSE REACTION
As with all alpha-two agonists, the potential for isolated cases of hypersensitivity, including paradoxical response (excitation) exists. Incidents of prolonged sedation, bradycardia, cyanosis, vomiting, apnea, death from circulatory failure with severe congestion of lungs, liver, kidney and recurrence of sedation after initial recovery have been reported in domestic species.
RECOMMENDED DOSE RANGE
The dose range for medetomidine in non-domestic species is wide and variable. In combination with ketamine in North American Cervidae, the dose can vary from 30mcg/kg to 80mcg/kg. Professionals are advised to refer to the Handbook of Wildlife Chemical Immobilization and the current published literature for the best information on the species, dose, and combinations that have been effective in field and clinical use.
ADMINISTRATION
Medetomidine may be administered intravenously and /or intramuscularly. In wildlife, dart or other remote delivery is the method for intramuscular injection. Following injection with medetomidine or medetomidine combinations, the animal should be allowed to rest quietly for at least 15 minutes post achieving sternal recumbency, as long as the animal is in a safe position and environment.
FDA Approved Presentation for Medetomidine hydrochloride
Medetomidine was approved by FDA in a 1mg/ml concentration. It is available in a 10mg/ml strength in Europe.
Compounded Forms Possible
10mg/ml and 20mg/ml strengths are compounded by ZooPharm upon prescription in the United States.
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