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Contra-indications, warnings, etc
Do not use in animals with cardiovascular disorders.
Do not use in animals with severe systemic disease or in animals that are moribund.
Do not use in case of known hypersensitivity to the active substance or to any of the excipients.
Precautions for use in animals
The administration of dexmedetomidine to puppies younger than 16 weeks and kittens younger than 12 weeks has not been studied.
The safety of dexmedetomidine has not been established in males intended for breeding. The safety of dexmedetomidine has not been established during pregnancy and lactation in the target species. Therefore the use of the product during pregnancy and lactation is not recommended.
In cats, corneal opacities may occur during sedation. The eyes should be protected by a suitable eye lubricant.
Treated animals should be kept warm and at a constant temperature, both during the procedure and recovery.
It is recommended that animals are fasted for 12 hours prior to Dexdomitor 0.5mg/ml administration. Water may be given.
After treatment, the animal should not be given water or food before it is able to swallow.
To be used with precaution in elderly animals.
Nervous, aggressive or excited animals should be given the possibility to calm down before initiation of treatment.
Frequent and regular monitoring of respiratory and cardiac function should be performed. Pulse oximetry may be useful but is not essential for adequate monitoring. Equipment for manual ventilation should be available in case of respiratory depression or apnoea when dexmedetomidine and ketamine are used sequentially to induce anaesthesia in cats. It is also advisable to have oxygen readily available, should hypoxaemia be detected or suspected.
Sick and debilitated dogs and cats should only be premedicated with dexmedetomidine before induction and maintenance of general anaesthesia based on a risk-benefit assessment.
Use of dexmedetomidine as a premedicant in dogs and cats significantly reduces the amount of induction drug required for induction of anaesthesia. Attention should be given during the administration of intravenous induction drugs to effect. Volatile anaesthetic requirements for maintenance anaesthesia are also reduced.
The use of other central nervous system depressants is expected to potentiate the effects of dexmedetomidine and therefore an appropriate dose adjustment should be made. Anticholinergics should be used with caution with dexmedetomidine.
Administration of atipamezole after dexmedetomidine rapidly reverses the effects and thus shortens the recovery period. Within 15 minutes dogs and cats are normally awake and standing.
Cats: After administration of 40 micrograms dexmedetomidine/ kg bw intramuscularly concurrently with 5 mg ketamine /kg bw to cats, the maximum concentration of dexmedetomidine increased two-fold but there was no effect on T max. The mean half-life of elimination of dexmedetomidine increased to 1.6 hours and the total exposure (AUC) increased by 50%.
A dose of 10 mg ketamine/ kg used concurrently with 40 micrograms dexmedetomidine/ kg may cause tachycardia.
Adverse reactions
By virtue of its alpha2-adrenergic activity, dexmedetomidine causes a decrease in heart rate and body temperature.
Blood pressure will increase initially and then return to normal or below normal.
In some dogs and cats, a decrease in respiratory rate may occur. Due to peripheral vasoconstriction and venous desaturation in the presence of normal arterial oxygenation, the mucous membranes may appear pale and/or with a blue tinge. Rare instances of pulmonary oedema have been reported.
Vomiting may occur 5-10 minutes after injection. Some dogs and cats may also vomit at the time of recovery.
Muscle tremors may occur during sedation. Corneal opacities may occur during sedation.
When dexmedetomidine and ketamine are used sequentially, with a 10 minute interval, cats may occasionally experience AV-block or extrasystole. Expected respiratory events are bradypnoea, intermittent respiratory patterns, hypoventilation, and apnoea. In clinical trials the incidence of hypoxaemia was common, especially within the 15 first minutes into dexmedetomidine-ketamine anaesthesia. Vomiting, hypothermia and nervousness have been reported after such use.
When dexmedetomidine and butorphanol are used concomitantly in dogs, bradypnoea, tachypnoea, an irregular respiratory pattern (20-30 sec apnoea followed by several rapid breaths), hypoxaemia, muscle twitch or tremor or paddling, excitation, hypersalivation, retching, vomiting, urination, skin erythema, a sudden arousal, or prolonged sedation may occur. Brady- and tachyarrhythmias have been reported. These may include profound sinus bradycardia, 1st and 2nd degree AV block, sinus arrest or pause, as well as atrial, supraventricular and ventricular premature complexes.
When dexmedetomidine is used as a premedicant in dogs bradypnoea, tachypnoea and vomiting may occur. Brady- and tachyarrhythmias have been reported and include profound sinus bradycardia, 1st and 2nd degree AV block and sinus arrest. Supraventricular and ventricular premature complexes, sinus pause and 3rd degree AV block may be observed in rare cases.
When dexmedetomidine is used as a premedicant in cats, vomiting, retching, pale mucous membranes, and low body temperature may occur. Intramuscular dosing at 40 mcg/kg (followed by ketamine or propofol) frequently resulted in sinus bradycardia and sinus arrhythmia, occasionally resulted in 1st degree atrioventricular block, and rarely resulted in supraventricular premature depolarizations, atrial bigeminy, sinus pauses, 2nd degree atrioventricular block, or escape beats/rhythms.
Dogs: In cases of overdosage, or if the effects of dexmedetomidine become potentially life-threatening, the appropriate dose of atipamezole is 10 times the initial dose of dexmedetomidine (micrograms/ kg bw or micrograms/ square meter body surface area). The dose volume of atipamezole at the concentration of 5 mg/ml equals the dose volume of Dexdomitor 0.5mg/ml that was given to the dog, regardless of route of administration of Dexdomitor 0.5mg/ml.
Cats: In cases of overdosage, or if the effects of dexmedetomidine become potentially life-threatening, the appropriate antagonist is atipamezole, administered by intramuscular injection, at the following dose: 5 times the initial dose dexmedetomidine in micrograms/kg bw. The dose volume of atipamazole at the concentration of 5mg/ml equates to half the volume of Dexdomitor 0.5mg/ml that was given to the cat.
After concurrent exposure to a triple (3X) overdose of dexmedetomidine and 15 mg ketamine/kg, atipamezole can be administered at the recommended dose level for reversal of effects induced by dexmedetomidine. At high serum concentrations of dexmedetomidine sedation is not increased although the level of analgesia does increase with further dose increases.
Operator Warnings
In case of accidental oral intake or self-injection, seek medical advice immediately and show the package insert to the physician but DO NOT DRIVE as sedation and changes in blood pressure may occur.
Avoid skin, eye or mucosal contact; the use of impermeable gloves is advisable. In case of skin or mucosal contact, wash the exposed skin immediately after exposure with large amounts of water and remove contaminated clothes that are in direct contact with skin. In case of eye contact, rinse abundantly with fresh water. If symptoms occur, seek the advice of a physician.
If pregnant women handle the product, special caution should be observed not to self-inject as uterine contractions and decreased foetal blood pressure may occur after accidental systemic exposure.
Advice to doctors: Dexdomitor 0.5mg/ml is an alpha2-adrenoreceptor agonist, symptoms after absorption may involve clinical effects including dose-dependent sedation, respiratory depression, bradycardia, hypotension, a dry mouth, and hyperglycaemia. Ventricular arrhythmias have also been reported. Respiratory and haemodynamic symptoms should be treated symptomatically. The specific alpha2 –adrenoceptor antagonist, atipamezole, which is approved for use in animals, has been used in humans only experimentally to antagonize dexmedetomidine-induced effects.
Persons with known hypersensitivity to the active substance or any of the excipients should administer the product with caution.