Chemicals / Complex Chemical Agents/ Chemical:

Medetomidine (with special reference to Ruminants, Hedgehogs, Elephants, Bears, Lagomorphs, Ferrets and Great Apes)

INFORMATION AVAILABLE

GENERAL CHEMICAL INFORMATION THERAPEUTIC INFORMATION [DOSE, FREQUENCY & ROUTE]

NUTRITIONAL INFORMATION

TOXICITY INFORMATION ENVIRONMENTAL INFORMATION
Information in this page has been entered to support the current volumes of Wildpro and further information will be added as new volumes are completed. This page is not intended to substitute for the manufacturer's data sheet and the information is not yet complete for all species, or for all contra-indications etc.

CAUTION: Before any pharmaceutical product is used, the manufacturer's data sheet, containing information on uses, dosage and administration, contra-indications, warnings etc., should always be consulted. It is important to remember that licensing of pharmaceutical products for use in a particular species/condition, as well as mandatory meat and milk withdrawal times for food-producing animals, varies between countries and changes with time. Withdrawal times also may vary between different pharmaceutical formulations and depending on route of administration. In the EU, the prescription cascade must be followed (see LCofC1.2H and W564.Apr05.w1); note that specific restrictions apply for food-producing animals. In the USA, FARAD may be consulted regarding residues and meat and milk withdrawal times.

General Chemical Information

Summary 
Alpha2-adrenergic agonist used mainly as a sedative and analgesic. (B201.6.w6, B263)

Return to Top of Page

Names and Formulae
Type Alpha2-adrenergic agonist. (B263)
Alternative Names Medetomidine hydrochloride. (B263); Domitor (Pfizer) UK (B201.6.w6)
Chemical Formula C13H16N2. (W324)
Chemical Structure
  • Exists as stereoisomers of which only the d-isomer is active. (B263)
Molecular Weight 200.2828. (W324)
Related Chemicals Detomidine, xylazine. (B201.6.w6)

Return to Top of Page

Physical Properties / Chemistry
Appearance
  • White/almost white, crystalline. (B263)

Melting point --
Boiling point --
Density --
Water solubility
  • Soluble in water. (B263)
Other solubility --
Acid/Base --

Return to Top of Page

Pharmacology & General Information
Pharmacology
  • Alpha adrenergic receptor agonist. (B263)
  • Reported to be more than ten times more specific than xylazine for alpha2 versus alpha1 receptors; alpha2:alpha1 selectivity factor of 1620. (B263)
  • CNS effects:
    • Depression (sedation). (B263)
    • Analgesia. (B263)
    • Anxiolytic effect. (B263)
  • Gastrointestinal effects:
    • decreased secretions, variable effects on intestinal muscle one). (B263)
  • Endocrine effects: (B263)
  • Cardiovascular effects:
    • peripheral and cardiac vasoconstriction, bradycardia, blanched or cyanotic mucous membranes, variable effect on blood pressure. (B263)
  • Respiratory effects:
    • Respiratory depression.
  • Renal effects:
  • Thermoregulatory effects:
    • Hypothermia. (B263)
  • Muscular effects:
    • Muscle relaxation. (B263)
Storage / Stability
  • Commercially available injection: store at room temperature (15-30C); protect from freezing. (B263)
Legal Category (In UK) POM (B266)

Return to Top of Page

References

Associated Techniques

--

ORGANISATIONS

--

ELECTRONIC LIBRARY
(Further Reading)
Click image for full contents list of ELECTRONIC LIBRARY

--
Authors Debra Bourne (V.w5)
Referees Suzanne I. Boardman (V.w6); Becki Lawson (V.w26)

Return to Top of Page

Therapeutic Information

Uses/Indications
Activity --
Appropriate Use
Limitations  
Notes

Return to Top of Page

Pharmacokinetics and Drug Interactions
Absorption /Bioavailability
  • Following intravenous or intramuscular injection, onset of effect in 5 minutes or 10 to 15 minutes respectively; responses following subcutaneous administration are unreliable. (B263)
  • Absorption occurs via the oral mucosa following sublingual administration in dogs; may be less efficacious than the same dose administered by intramuscular injection. (B263)
Distribution Sheep:
Plasma Protein binding / Storage --
Elimination Route --
Elimination half-life / Clearance Rate Sheep:
  • Following intravenous administration at 15 g/kg to adult female sheep of various breeds, elimination of the drug was rapid; the elimination half-life was 37.85 +/- 2.84 min (mean +/- SEM) and total body clearance varied between 16.29 and 151.81 mL/min.kg (mean 57.58 +/- 14.84) mL/min.kg. (J289.19.w1)
Drug Interactions
  • Hypoxaemia may occur if medetomidine premedication is followed by propofol; dosage adjustment and monitoring are required. (B263)
  • If used concurrently with fentanyl, butorphanol, or meperidine both beneficial (sedative and analgesic) and adverse effects may result; reduced dosages and monitoring are required. (B263)
  • Use of atropine or glycopyrrolate to treat medetomidine-related bradycardia may result in tachycardia and hypertension: such use is therefore controversial. (B263)

Return to Top of Page

Administration
Formulations available
  • Domitor (Pfizer) UK; medetomidine hydrochloride 1 mg/mL, 10 mL, for injection in dogs and cats. (B201.6.w6)
Doses / Administration Routes / Frequencies Note: medetomidine doses are sometimes given in microgrammes per kilogram bodyweight, indicated in the text below as "g/kg". Other drug doses are generally given in milligrams per kilogram bodyweight (mg/kg).

Sheep:

  • A dose of 5 g/kg intravenously has been found to give analgesia similar to that from high dose (15 g/kg) fentanyl. (J3.135.w3)
  • Medetomidine administered at 2 to 7 g/kg intravenously the healthy adult sheep significantly (P<0.05) raised the threshold to a noxious mechanical stimulus and the effect was dose-dependent. The graph shown for a dose of 5 g/kg indicated the threshold to be considerably raised by five minutes after administration of the medetomidine and returning to control levels by about 50 to 60 minutes. (J3.135.w3)

Erinaceus europaeus - West European Hedgehog:

  • Medetomidine 0.1 mg/kg intramuscular. Light sedation; reversal using atipamezole. (B267)
  • Medetomidine 0.1 mg/kg. intramuscular. For sedation. (D107)
  • Medetomidine 100 g intramuscular. In combination with ketamine 10-20 mg/kg for general anaesthesia. Reversal using atipamezole 300-500 g/kg. (B284.6.w6)
  • Medetomidine 0.2 mg / ketamine 5.0 mg/kg; subcutaneous injection. Relaxation and deep sedation but not necessarily anaesthesia sufficient for e.g. ear-tagging without response. Reversal of medetomidine using atipamezole (1.0 mg/kg intramuscularly). (J2.26.w1)
  • Medetomidine 0.1 mg / ketamine 5.0 mg/kg; intramuscular injection. Anaesthesia. Reversal of medetomidine using atipamezole 0.3-0.5 mg/kg. (B267, D93)
  • Medetomidine 0.1 mg / ketamine 5.0-15.0 mg/kg; intramuscular injection. Anaesthesia. Reversal of medetomidine using atipamezole 0.3-0.5 mg/kg. (D107)
  • Medetomidine 0.2 mg / ketamine 2 mg/kg / fentanyl 0.1 mg/kg; subcutaneous injection. Anaesthesia with good muscle relaxation. Reversal of medetomidine  using atipamezole (1.0 mg/kg intramuscular) and of fentanyl using naloxone (0.16 mg/kg intramuscular). (J2.26.w1)

Elephants:

The following information is taken with permission directly from the Elephant Care International website (W580.Aug2005.w22):

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. Higher doses may be needed in wild or excited animals. Unless otherwise specified, doses refer to captive elephants. The information provided here should be used as a guideline only. Consultation with experienced colleagues is advised.

a) 3-5 g/kg IM (Sarma et.al 2002).

Elephant References:
a) Sarma,B., Pathak,S.C., and Sarma,K.K. 2002. Medetomidine a novel immobilizing agent for the elephant (Elephas maximus). Res Vet Sci 73:(3):315-317
Abstract: Medetomidine was injected by the intramuscular route at the rates of 3 and 5 micrograms/kg body weight into two groups of Indian elephants (Elephas maximus). Sedation was induced at 6.20 (0.81) and 5.90 (0.60) min respectively after injection. The duration of anaesthesia was 66.20 (10.4) and 134.20 (24.12) min, respectively and recovery occurred at 125.80 (25.23) and 205.89 (29.3) min. The notable signs of sedation exhibited by the elephants were protrusion of penis, complete relaxation of trunk, flaccidity of tail and drooping of the ears with a head down position. During sedation, physiological parameters recorded were bradycardia, decreased respiration and hypothermia.

Bears:

1) In combination with Tiletamine-Zolazepam (see Medetomidine-Tiletamine-Zolazepam Anaesthesia in Bears):

  • Medetomidine 0.03 mg/kg plus Tiletamine-Zolazepam 3 mg/kg gives a predictable, smooth induction, excellent immobilisation and good recovery following reversal (atipamezole, 2.5 - 5 times the medetomidine dose on a mg-to-mg basis). (J213.4.w3) 
    • Helarctos malayanus - Sun bear
      • For bears rescued from bear bile farms, 0.01 mg/kg medetomidine plus 1.0 mg/kg tiletamine-zolazepam, by intramuscular injection. (V.w90)
        • This provides Stage 2/Stage3 anaesthesia for about 30-45 minutes, allowing physical examination or minor surgical procedures such as wound treatment, skin biopsy and castration. (V.w90)
        • For longer and/or more invasive procedures, anaesthesia is prolonged with inhalant anaesthesia.
        • The medetomidine is reversed with atipamezole. (V.w90)
    • Ursus americanus - American black bear: 
      • Medetomidine 52 g/kg, Tiletamine-zolazepam 1.7 mg/kg. (D156.w2, J1.33.w16)
    • Ursus arctos - Brown bear
      • Medetomidine 0.06 mg/kg, Tiletamine-zolazepam 2 mg/kg. (B345.6.w6, B336.51.w51)
      • Medetomidine 35 g/kg, Tiletamine-zolazepam 4.8 mg/kg. (D156.w2)
      • For zoo bears medetomidine 0.01 mg/kg plus tiletamine-zolazepam 1.0 mg/kg or medetomidine 0.03 mg/kg plus tiletamine-zolazepam 0.5 mg/kg. (P1.1997.w9)
      • For free-ranging brown bears in Scandinavia:
        • 20-30 kg: medetomidine 0.04 mg/kg + tiletamine-zolazepam 5.0 mg/kg. (P1.1997.w9)
          • or for 1.5 year-old cubs, darts containing medetomidine 1 mg plus tiletamine-zolazepam 125 mg. (P1.1997.w9)
        • 40-60 kg: medetomidine 0.02 mg/kg + tiletamine-zolazepam 5.0 mg/kg. (P1.1997.w9)
          • or for 2.5-year-old bears darts containing medetomidine 1 mg plus tiletamine-zolazepam 250 mg. (P1.1997.w9)
        • 80-140 kg: medetomidine 0.02 mg/kg + tiletamine-zolazepam 4.0 mg/kg. (P1.1997.w9)
          • or for adult female bears darts containing medetomidine 2 mg plus tiletamine-zolazepam 500 mg. (P1.1997.w9)
        • 200-250 kg: medetomidine 0.015 mg/kg + tiletamine-zolazepam 3.0 mg/kg. (P1.1997.w9)
          • or for adult male bears darts containing medetomidine 2.5 mg plus tiletamine-zolazepam 750 mg. (P1.1997.w9)
      • For free-ranging brown bears in Sweden and Europe, based on 575 immobilisations of 241 individual bears, the following have been recommended: (P504.2001.w5)
        • Yearlings, 15-45 kg bodyweight: 0.5 mg medetomidine + 125 mg tiletamine-zolazepam. 
        • Two-year-olds and three-year-olds, 45-70 kg bodyweight: 1 mg medetomidine plus 250 mg tiletamine-zolazepam. 
        • Adult females and subadult males, 70-120 kg: 2 mg medetomidine plus 500 mg tiletamine-zolazepam. 
        • Small adult males 120-180 kg: 3 mg medetomidine plus 750 mg tiletamine-zolazepam. 
        • Large adult males: 180-240 kg: 4 mg medetomidine plus 1,000 mg tiletamine-zolazepam.
        • All bears, if the bear is not recumbent after 15 minutes, repeat the full dose. (P504.2001.w5)
      • For bears rescued from bear bile farms, 0.01 mg/kg medetomidine plus 1.0 mg/kg tiletamine-zolazepam, by intramuscular injection. (V.w90)
        • This provides Stage 2/Stage3 anaesthesia for about 30-45 minutes, allowing physical examination or minor surgical procedures such as wound treatment, skin biopsy and castration. (V.w90)
        • For longer and/or more invasive procedures, anaesthesia is prolonged with inhalant anaesthesia.
        • The medetomidine is reversed with atipamezole. (V.w90)
    • Ursus maritimus - Polar bear:
      • Medetomidine 75 g, Tiletamine-zolazepam 2.2 mg/kg. (D156.w2)
      • Medetomidine 34-225 g/kg, tiletamine-zolazepam 1.14-7.43 mg/kg. (J2.30.w5)
      • Medetomidine 74.8 +/- 11.8 g/kg medetomidine + 2.2 +/- 0.3 mg/kg tiletamine-zolazepam. (J2.30.w6)
      • Medetomidine 60 g/kg plus tiletamine-zolazepam 2.0 mg/kg (1.0 mg/kg each) intended dose; actual medetomidine mean 70 g/kg (median 64 g/kg), tiletamine-zolazepam mean 2.3 mg/kg (median 2.1 mg/kg) for bears requiring only one dose for immobilization. (J1.33.w17)
      • Medetomidine 0.01 mg/kg plus tiletamine-zolazepam 1.0 mg/kg OR medetomidine 0.015 mg/kg plus tiletamine-zolazepam 0.5 mg/kg. (P1.1997.w9)
      • Medetomidine mean 74.8 +/- 11.8 g/kg, tiletamine-zolazepam mean 2.2 +/- 0.3 mg/kg (intended dose estimated medetomidine 52 g/kg plus tiletamine-zolazepam 0.86 mg/kg). (P20.1998.w10)
    • Ursus thibetanus - Asiatic black bear:
      • For bears rescued from bear bile farms, 0.01 mg/kg medetomidine plus 1.0 mg/kg tiletamine-zolazepam, by intramuscular injection. (V.w90)
        • This provides Stage 2/Stage3 anaesthesia for about 30-45 minutes, allowing physical examination or minor surgical procedures such as wound treatment, skin biopsy and castration. (V.w90)
        • For longer and/or more invasive procedures, anaesthesia is prolonged with inhalant anaesthesia.
        • The medetomidine is reversed with atipamezole. (V.w90)
For further information see: Medetomidine-Tiletamine-Zolazepam Anaesthesia in Bears

2) In combination with Ketamine (see Medetomidine-Ketamine Anaesthesia in Bears):

  • Medetomidine 30-50 g/kg plus ketamine 1-2.5 mg/kg. (B407.w18)
  • This combination is useful for short procedures in smaller bears, with experienced personnel. However, it is not recommended for larger bears because sudden recoveries have occurred in Ursus arctos - Brown bear and Ursus maritimus - Polar bear. (D156.w2, P1.1997.w9) See: Medetomidine-Ketamine Anaesthesia in Bears
    • Medetomidine 30-50 g/kg plus ketamine 1-2.5 mg/kg. (B407.w18)
    • In captive Ursus arctos - Brown bear, medetomidine 20-30 g/kg + ketamine 0.5-1.0 mg/kg gave an induction time averaging six minutes. (P7.1.w10)
    • In wild Ursus arctos - Brown bear darted from a helicopter, medetomidine 60-80 g/kg + ketamine 1.0-1.6 mg/kg was required. (P7.1.w10)
      • Supplementation with ketamine, 1.0 mg/kg intravenously was required to enable an incisor to be extracted without the bear showing a pain reaction. (P7.1.w10)
    • In Ursus maritimus - Polar bear: doses used varied from medetomidine 77-352 g/kg and ketamine from 1.92-8.81 mg/kg. Variation was due to incorrect body mass estimation and in some cases (four of 12 bears) multiple injections required. (J2.30.w5)
    • In nine captive Ursus maritimus - Polar bear, medetomidine 30 g/kg + ketamine 1.0-1.5 mg/kg produced adequate immobilisation. (P1.1990.w6)
    • In eight Ursus arctos - Brown bear, medetomidine 30-40 g/kg + ketamine 1.0-1.5 mg/kg produced adequate immobilisation. (P1.1990.w6)
    • In Himalayan bear (Ursus thibetanus - Asiatic black bear) medetomidine 30-40 g/kg + ketamine 1.0-1.5 mg/kg produced adequate immobilisation. (P1.1990.w6)
    • In Ursus americanus - American black bear medetomidine 30-40 g/kg + ketamine 1.0-1.5 mg/kg produced adequate immobilisation. (P1.1990.w6)
    • In five Ursus maritimus - Polar bear, 159 +/- 34 g/kg medetomidine and 4.0 +/- 0.8 mg/kg ketamine. (P1.1996.w5)
    • In captive Ursus maritimus - Polar bear (two adult females and three subadults), medetomidine 20-33 g/kg plus ketamine 1-3 mg/kg (mean 1.5 mg/kg) was sufficient to enable translocation and skin biopsies. (J2.21.w3)
    • In captive Ursus arctos - Brown bear (12 adults, 11 subadults or juveniles) 25-35 g/kg medetomidine plus 0.7 - 1.5 mg/kg ketamine was sufficient for translocation, tattooing and castration. However, in wild brown bears shot from a helicopter, higher doses were needed. (J2.21.w3)

    For further information see: Medetomidine-Ketamine Anaesthesia in Bears

Lagomorphs - Oryctolagus cuniculus domesticus - Domestic rabbit:

Ferrets - Mustela putorius furo - Ferret:

  • 0.1 mg/kg subcutaneously or intramuscularly. (B602.41.w41)
    • Ketamine 5 - 8 mg/kg plus medetomidine 0.08 - 0.1 mg/kg. (B602.41.w41)
  • 0.050 mL per 1.25 kg ferret intramuscularly. (B626.App.w22)
    • Ketamine 10 mg/kg plus medetomidine 120 g/kg intramuscularly. (B626.App.w22)
    • Ketamine 5 mg/kg plus medetomidine 80 g plus Butorphanol 100 g intramuscularly or subcutaneously. Note: if the 100 g dose of butorphanol is exceeded, hypoxia may occur. (B626.App.w22)
  • 0.08 - 0.10 mg/kg subcutaneously or intramuscularly. provides light sedation; may cause hypotension and bradycardia. Rarely used alone. Oxygen should be available, and atipamezole for reversal. (B631.22.w22)
    • Ketamine 5 - 8 mg/kg plus medetomidine 0.08 - 0.1 mg/kg intramuscularly. Light anaesthesia with analgesia, hypotension and respiratory depression. Oxygen should be available. Reverse medetomidine with atipamezole. (B631.22.w22)
    • Medetomidine 0.08 mg/kg plus Butorphanol 0.1 mg/kg intramuscularly. Anaesthetic. Causes hypotension and respiratory depression. Oxygen should be available, and atipamezole for reversal. (B631.22.w22)
  • 80 micrograms/kg intramuscularly. Can be reversed using atipamezole 400 mg/kg. (J213.3.w1)
    • Medetomidine 80 mg/kg plus butorphanol 0.1 mg/kg intramuscularly . Should be drawn up in separate syringes but can be combined into a single syringe for administration. (J213.3.w1)

Great Apes

  • 0.02 - 0.05 mg/kg intramuscularly. (B336.39.w39)
    • For chemical restraint, in combination with other agents. Can reduce the quantity of Ketamine required as much as five fold. (B336.39.w39)
    • Can be reversed with Atipamezole, 0.1 -0.25 mg/kg intramuscularly. (B336.39.w39)
  • Induction of anaesthesia:
    • Ketamine 2.0 mg/kg plus Medetomidine 0.03 - 0.04 mg/kg can be used for induction of anaesthesia in great apes. Oxygen should be supplied, plus additional inhalant anaesthetic agent as required. (B336.39.w39)
    • Ketamine 2.0 - 3.0 mg/kg plus Medetomidine 0.02 - 0.04 mg/kg plus Butorphanol 0.2 - 0.4 mg/kg can be used for induction of anaesthesia in great apes. Oxygen should be supplied, plus additional inhalant anaesthetic agent as required. The anaesthetised individual should be monitored closely. (B336.39.w39)
      • Atipamezole can be used for reversal of the medetomidine, and Naloxone for reversal of the butorphanol. (B336.39.w39)
    • Tiletamine-Zolazepam 1.25 mg/kg plus Medetomidine 0.03 - 0.04 mg/kg can be used for induction of anaesthesia in great apes. Oxygen should be supplied, plus additional inhalant anaesthetic agent as required. (B336.39.w39)
  • Adult Pan troglodytes - Chimpanzee: Ketamine 2 - 6 mg/kg intramuscularly followed by medetomidine 30 - 60 g intramuscularly. (W768.Jun2012.w1)
Monitoring parameters
  • Level of sedation and analgesia. (B263)
  • Heart rate and rhythm. (B263)
  • Body temperature. (B263)
  • Blood pressure. (B263)
  • Respiratory rate. (B263)
  • Pulse oxymetry. (B263)

Return to Top of Page

Withdrawal period / Withholding time
Notes --

Return to Top of Page

Toxic Information

Toxic effects of Pharmaceutical Products
Contraindications / Precautions
  • Contraindicated in individuals receiving adrenoceptor stimulants (such as epinephrine (adrenaline)). (B201.6.w6, B263)
  • Contraindicated during pregnancy. (B201.6.w6, B263)
  • Caution in individuals with cardiovascular disease. (B201.6.w6, B263)
  • Caution in very young/very old animals. (B263)
  • Contraindicated in individuals with respiratory disease. (B263)
  • Contraindicated in individuals with hepatic or renal disease. (B263)
  • Caution in debilitated individuals. (B201.6.w6, B263)
  • Contraindicated in individuals stressed by heat, cold or fatigue. (B263)
  • Effect may be decreased in dogs which are highly excited/agitated; a period of quiet rest is recommended prior to administration in such individuals. (B263)
Adverse Effects / Side Effects / Warnings
  • Bradycardia, occasional atrio-ventricular block. (B263)
  • Decreased respiration. (B263)
  • Hypothermia. (B201.6.w6, B263)
  • Polyuria. (B201.6.w6)(B263)
  • Vomiting (occasional). (B201.6.w6)(B263)
  • Hyperglycaemia. (B263)
  • Pain on intramuscular injection. (B263)
  • Rarely: prolonged sedation, paradoxical excitation, hypersensitivity, apnoea, fatal circulatory failure. (B263)
Operator Warnings --
Overdose / Acute Toxicity
  • Occasional deaths reported in dogs receiving twice the recommended dose. (B263)
  • Adverse effects may occur in individuals receiving 5 times the intravenous dose or 10 times the intramuscular dose, although this may be tolerated. (B263)
  • Atipamezole is recommended for treatment of medetomidine-induced effects. (B263)

Return to Top of Page

Detailed Toxicological Information
Classification --
Acute Toxicity --
Chronic Toxicity --
Reproductive effects
  • Insufficient data regarding safety. (B263)
Teratogenic effects --
Mutagenic effects --
Carcinogenic effects

--

Organ toxicity --
Bird Toxicity --
Aquatic organism activity --
Other organism toxicity --

Return to Top of Page

Nutrient Information

Nutritional Data
Sources --
Biological Use --
Recommended Daily Allowance / Recommended level in food --
Stability in food (Storage time) --
Interactions --

Return to Top of Page

External / Environmental Information

External / Environmental Uses
Use --
Formulation --
Application method --
Application Concentration --
Persistence of Effect / Frequency of Application --

Return to Top of Page

Sources in the Environment
Natural sources --
Human-associated sources --

Return to Top of Page

Effects on the Environment
Effects in the aquatic environment

--

Effects on land --

Return to Top of Page

Persistence in the Environment
Breakdown in soil and groundwater

--

Breakdown in water --
Breakdown in vegetation --

Return to Top of Page