Azaperone tartrate
Applications in Veterinary Medicine and Wildlife Management
Azaperone is a neuroleptic sedative belonging to the butyrophenone class of pharmaceuticals. Butyrophenones work through the mechanism of central dopamine and peripheral adrenergic blockage to produce a strong anticholinergic effect. The other butyrophenone routinely used in wildlife is haloperidol as a longer acting tranquilizer.
General Information and History
Azaperone is the product of original research and development by Janssen Pharmaceutica of Beerse, Belgium. Azaperone is indicated for use in anti-aggressiveness, stress, sedation and anesthesia in swine. It is available outside of the United States as a 4% injectable solution for deep intramuscular injection at a dose of 0.4 to 2.0 mg per kilogram of body weight depending upon the desired effect or outcome.
Azaperone was approved by the FDA for use in swine in the 1970s. It was marketed under the trade name Stresnil until approximately 1995. It is no longer commercially produced in the United States. It is available only on prescription through the custom compounding pharmacy ZooPharm.
Use in Wildlife Management
Azaperone is most commonly used in combination with opiates and alpha-two agonists. In these combinations the dose is from 0.15 to 0.30 mg/kg body weight. If used alone the dose for sedation ranges from 0.5 to 2.0 mg/kg body weight depending on the species and desired level of effect. Combined with fentanyl alone it has been effective for use in sea otters. [Williams et al. 1981, J Wildl Dis 17(3):337-342]
In non-domestic species, azaperone has broad applications as a sedative or in combination with other drugs such as etorphine, fentanyl, and thiafentanyl oxalate (A3080) in immobilization and capture protocols. In New Zealand, it is used in an approved mixture with fentanyl and xylazine (Fentaz). It is routinely used in Africa as part of a sedation protocol for transport and environmental adaptation along with haloperidol and zuclopenthixol.
New uses of azaperone in the United States are being found in light of its recent availability as a compounded pharmaceutical. Additional species, uses and doses are found in the Handbook of Wildlife Chemical Immobilization (Kreeger et al.) available from Wildlife Pharmaceuticals Inc, Fort Collins, Colorado (970-484-6267)
Use in Domestic Species
Azaperone has a single use in domestic species as a sedative for swine.
Pharmacology and Chemistry
Azaperone tartrate produces predictable psychomotor sedation without narcosis after intramuscular administration. It was developed for approval in domestic swine because of its pronounced sedative action, good tolerance and wide safety margin. Anti-shock activity of azaperone is 60 times higher than that of propionylpromazine and its adrenalytic action is 20 times lower.
Azaperone tartrate has the chemical structure of 4’-fluoro-[4-(2-pyridyl)-1- piperazinyl]-butyrophenone. It is light sensitive and should be protected from light and heat. In solution, its pH is approximately 4.
Pharmacokinetics
Azaperone is rapidly absorbed from the injection site with peak concentrations in plasma occurring within one hour after administration. Elimination from plasma is ½-2.5 hr due to rapid and extensive metabolism. Metabolic pathways are 1) reduction of the butanone 2) oxidative N-dearylation 3) hydroxylation of the pyridine group. The target tissue for azaperone and its metabolites is the liver. Low residue levels are present in muscle and other edible tissues.
CONTRAINDICATIONS AND PRECAUTIONS
Animals showed reduced activity for about 6 hours post-induction with azaperone. It should not be used in game species 30 days prior to a legal hunting season. The effects of azaperone are NOT reversed with the narcotic or alpha-two reversal agents. Animals may exhibit extra pyramidal signs at the higher dose rates.
WARNING:
Azaperone has no reversal, i.e. antagonist (antidote). Azaperone may cause hypotension and, at low doses, may cause excitement in equids.
ADVERSE REACTION
Hyper-salivation and tachypnea may occur.
If used alone the dose for sedation is 0.5 to 2.0mg/kg body weight depending on the species and desired level of effect. Uses and dose rates in combination with other drugs are found in The Handbook of Wildlife Chemical Immobilization available from Wildlife Pharmaceuticals Inc, Fort Collins, Colorado.
ADMINISTRATION
Recommended route of administration is deep intramuscular injection.
FDA Approved Presentation for Azaperone tartrate
Azaperone was approved by the FDA in the 50mg/ml concentration.
Compounded Forms Possible
50-100mg/ml concentrations are compounded by ZooPharm.
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