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Detomidine HCl

The Elephant Formulary
© 2003-06 Susan K. Mikota DVM and Donald C. Plumb, Pharm.D.
Published by Elephant Care International -
www.elephantcare.org


Elephant specific information, if available, is in blue.

Chemistry - An imidazoline derivative alpha2-adrenergic agonist, detomidine HCl occurs as a white crystalline substance that is soluble in water.

 

Storage/Stability/Compatibility - Detomidine HCl for injection should be stored at room temperature (15-30°C) and be protected from light.

 

Pharmacology - Detomidine, like xylazine is an alpha2-adrenergic agonist that produces a dose-dependent sedative and analgesic effect, but also has cardiac and respiratory effects. For more information refer to the xylazine monograph or the adverse effects section below.

 

Uses/Indications - At the present time detomidine is only approved for use as a sedative analgesic in horses, but it also has been used clinically in other species.

 

Pharmacokinetics - Detomidine is well absorbed after oral administration, but is used only parenterally at the present time. The drug is apparently rapidly distributed into tissues, including the brain after parenteral administration and is extensively metabolized and then excreted primarily into the urine.

 

Contraindications/Precautions/Reproductive Safety - Detomidine is contraindicated in horses with preexisting AV or SA heart block, severe coronary insufficiency, cerebrovascular disease, respiratory disease or chronic renal failure. It should be used with caution in animals with endo­toxic or traumatic shock or approaching shock, and advanced hepatic or renal disease. Horses who are stressed due to temperature extremes, fatigue, or high altitude should also receive the drug with caution.

 

Although animals may appear to be deeply sedated, some may respond to external stimuli; use appropriate caution. The manufacturer recommends allowing the horse to stand quietly for 5 minutes prior to injection and for 10-15 minutes after injection to improve the effect of the drug. After administering detomidine, protect the animal from temperature extremes.

 

Adverse Effects/Warnings - Detomidine can cause an initial rise in blood pressure which is then followed by bradycardia and heart block. Atropine at 0.02 mg/kg IV has been successfully used to prevent or correct the bradycardia that may be seen when the detomidine is used at labeled dosages. Also, piloerection, sweating, salivation, slight muscle tremors, and penile prolapse may all be noted after injection.

 

Overdosage/Acute Toxicity - The manufacturer states that detomidine is tolerated by horses at doses 5 times (0.2 mg/kg) the high dose level (0.04 mg/kg). Doses of 0.4 mg/kg given daily for 3 consecutive days produced microscopic foci of myocardial necrosis in 1 of 8 horses tested. Doses of 10-40 times those recommended can cause severe respiratory and cardiovascular changes which can become irreversible and cause death. Yohimbine theoretically could be used to reverse some or all of the effects of the drug, but not enough clinical experience has been reported to make any recommendations for its use at this time.

 

Drug Interactions - The manufacturer warns against using this agent with intravenous potentiated sulfonamides (e.g., trimethoprim/sulfa) as fatal dysrhythmias may occur, and to use with extreme caution in combination with other sedative or analgesic drugs. Because this is a rela­tively new drug, more interactions may be forthcoming; refer to the xylazine monograph for more information on interactions with alpha2-adrenergic agonists.

 

Doses -

Horses:

For sedation/analgesia:

a)   20 - 40 micrograms/kg (0.02 - 0.04 mg/kg) IV or IM (IV only for analgesia). Effects generally occur within 2-5 minutes. Lower dose will generally provide 30-90 minutes of sedation and 30-45 minutes of analgesia. The higher dose will generally provide 90-120 minutes of sedation and 45-75 minutes of analgesia. Allow animal to rest quietly prior to and after injection. (Package insert; Dormosedan®—SKB)

 

 

Monitoring Parameters -

1)   Level of sedation, analgesia

2)   Cardiac rate/rhythm; blood pressure if indicated

 

Client Information - This drug should be used in a professionally supervised setting by individuals familiar with its properties.

 

Dosage Forms/Preparations/FDA Approval Status/Withholding Times -

 

Veterinary-Approved Products:

Detomidine HCl for Injection  10 mg/ml in 5 and 20 ml vials

Dormosedan®  (Pfizer); (Rx) Approved for use in horses.

The trade name, Domosedan®  may be used in countries outside of the United States.

 

Human-Approved Products: None

 

Elephants:

 

CAUTION!  Sedative and anesthetic drug dosages for African elephants often vary from those for Asian elephants.  Do not assume that the recommendations for one species can be applied to the other.  Significant variation may also occur between individual elephants.  The information provided here should be used as a guideline only.  Consultation with experienced colleagues is advised. 

 

a) 5.5 µg/kg IM for standing sedation in Asian elephants (deSilva 1994)

 

Elephant References:

a) deSilva, D.D.N. and Kuruwita, V.Y. 1994.  Sedation of wild elephants (Elephas maximus Ceylonicus) using Detomidine HCL (“Domosedan”) in Sri Lanka. 5th International Congress of Veterinary Anesthesia.

Eight wild elephants weighing 3818-4500 kg were sedated using detomidine HCl 1% (Farmos) after being captured using Large Animal Immobilon (C-Vet) and revived with Revivon (C-Vet) in the process of wild elephant capture and translocation program carried out in Sri Lanka.  The total volume of detomidine used on each animal ranged from 2.0 to 2.5 ml using a Cap-Chur pistol.  Exsheathment of the penis in males was evident within 5 to 10 minutes of administration of detomidine.  From 5 minutes post-administration, gradual flaccidity of the trunk was observed and complete “limping” of the trunk was seen in 12 to 15 minutes.  Dribbling of urine, saliva, ptosis, gradual cessation of ear flapping were the other changes indicating sedation.  Seven out of 8 animals remained standing and were nonresponsive to low threshold physical or auditory stimuli, but moved steadily when traction was applied on the ropes tying the legs.  With this dosage of the drug, animals could be loaded onto a truck within 30-45 minutes of medication and were ready for transportation.  Antisedan (Farmos) had to be given to one animal which adopted lateral recumbency after detomidine.  After sedating and loading into trucks, the elephants were transported to a distance of 40 to 100 km (average transport time was 8 hours) during which there was no need for further “topping-up”.  Animals started eating and moving the trunk about 6 hours after detomidine administration but never adopted a recumbent position while being transported.  It is concluded that wild elephants are very sensitive to detomidine and the dosage needed is much lower (approximately 5.5 µg/kg) than that needed for some other species of animals (equine and bovine).

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