Clinical data | |
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Trade names | Atravet, Acezine 2 |
AHFS/Drugs.com | International Drug Names |
Routes of administration | IV, IM, SQ, oral [1] [2] |
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Pharmacokinetic data | |
Bioavailability | 6.6 L/kg, high volume of distribution |
Elimination half-life | 3 hours in horses, 15.9 hours in canines |
Excretion | urine |
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CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.000.451 |
Chemical and physical data | |
Formula | C19H22N2OS |
Molar mass | 326.46 g·mol−1 |
3D model (JSmol) | |
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Acepromazine, acetopromazine, or acetylpromazine (commonly known as ACP, Ace, or by the trade names Atravet or Acezine 2, number depending on mg/ml dose) is a phenothiazine derivative antipsychotic drug. It was used in humans during the 1950s as an antipsychotic, [4] but is now almost exclusively used on animals as a sedative and antiemetic. A closely related analogue, chlorpromazine, is still used in humans.
The standard pharmaceutical preparation, acepromazine maleate, is used in veterinary medicine in dogs and cats. It is used widely in horses as a pre-anesthetic sedative and has been shown to reduce anesthesia related death. [5] However, it should be used with caution (but is not absolutely contraindicated) in stallions due to the risk of paraphimosis and priapism. [6] Its potential for cardiac effects can be profound, namely hypotension due to peripheral vasodilation, so it should be avoided or used with caution in geriatric or debilitated animals. [7]
The clinical pharmacology of acepromazine is similar to that of other phenothiazine derived anti-psychotic agents. The primary behavioral effects are attributed to its potent antagonism of post-synaptic D2 receptors and, to a lesser degree, the other D2-like receptors. Additional effects are related to its appreciable antagonistic effects on various other receptors, including the α1-adrenergic receptors, H1 receptors, and muscarinic acetylcholine receptors. It is metabolized by the liver, oxidized to produce its primary metabolite, hydroxyethylpromazine sulfoxide, which is then excreted in the urine. [8] [9] : 115 Its action at the chemoreceptor trigger zone (in the area postrema) and the solitary nucleus (in the medulla oblongata) allow it to have an antiemetic effect. [10] [11]
The most common uses of acepromazine in animals are as an oral sedative before stressful events (such as thunderstorms), an injectable tranquilizer for particularly aggressive or fractious animals, and in combination with analgesics and other sedatives. It is also labeled for use in preventing motion sickness. [12] Its effects as a CNS depressant means that fewer opiates are required to reach the same amount of sedation, and it prevents the arrhythmia and vomiting that many opiates induce.
While acepromazine is also used in cats, its absorption is erratic and can vary between individuals. It also generally induces less sedation than in dogs. [13] [14] It also causes spontaneous motor activity (in both cats and dogs, but more often in cats) by blocking dopamine receptors in the striatum and substantia nigra. [15]
Literature from the 1950s raised concerns about phenothiazine-induced seizures in human patients. For this reason, caution has typically been advised when contemplating acepromazine use in epileptic canine patients, as it was widely believed to lower the seizures threshold. More current studies, however, have failed to show a positive association between use of acepromazine and seizure activity [9] : 116 [16] and show a possible role for acepromazine in seizure control: in a retrospective study at University of Tennessee, acepromazine was administered for tranquilization to 36 dogs with a prior history of seizures and to decrease seizure activity in 11 dogs. No seizures were seen within 16 hours of acepromazine administration in the 36 dogs that received the drug, and the seizures abated for 1.5 to 8 hours (n=6) or did not recur (n=2) in eight of 10 dogs that were actively seizing. Excitement-induced seizures were reduced for 2 months in one dog. [17] A second retrospective study also concluded that administration of acepromazine to dogs with prior or acute seizure history did not potentiate seizures, and there was some trend toward seizure reduction. [18] The original seizure cautions reported in the 1950s were in human patients on relatively high doses of the antipsychotic chlorpromazine while the doses of acepromazine used in the two published veterinary studies cited above are much lower.
In some boxers, acepromazine can cause vasovagal syncope (due to a decreased stimulation of the sympathetic nervous system) and hypotension (due to vasodilation), leading to collapse. [20] This may occur only in certain families of boxers, but the unknown risk to an individual dog means that acepromazine should be used at reduced doses, or not at all, in this breed. [15] Individual dogs of any breed can have a profound reaction characterized by hypotension, especially if there is an underlying heart problem.
In giant-breed dogs and sighthounds, the sedative effects of acepromazine may last for 12–24 hours, which is much longer than the usual 3–4 hours. [16] [20]
P-glycoprotein (P-gp), also known as multidrug resistant protein 1 (MDR1), is a protein found in cell membranes which is important in the metabolism and excretion of some drugs, [9] : 41–58 such as acepromazine and ivermectin. [21] This protein is encoded by the ABCB1 gene (previously known as the MDR1 gene). A mutation in ABCB1 prevents P-gp from being correctly produced, so that dogs with this mutation have an increased sensitivity to drugs (such as acepromazine) which are substrates of P-gp. [21] Dogs which are heterozygous (that is, which have one functioning ABCB1 gene, and one non-functioning gene) are less sensitive to acepromazine than dogs which are homozygous (that is, which have two copies of the mutant gene). 75% of Collies carry the mutated ABCB1 gene, as do 50% of Australian Shepherds. Other affected breeds include: Border Collie, English Shepherd, German Shepherd, Old English Sheepdog, and Sighthounds, shelties, long haired greyhound. [21]
Tests for this mutation are available. [22]
In equine surgery, premedication with acepromazine has been shown to reduce the perianaesthetic mortality rate, possibly due to its actions as a sedative and anxiolytic. [5] It is less effective as a sedative if the horse is already excited. [23]
Additionally, acepromazine is used as a vasodilator in the treatment of laminitis, where an oral dose equivalent to "mild sedation" is commonly used, although the dose used is highly dependent on the treating veterinarian. While it is shown to elicit vasodilation in the distal limb, evidence showing its efficacy at increasing perfusion in the laminae is lacking. It is also sometimes used to treat a horse experiencing equine exertional rhabdomyolysis. [7]
Acepromazine should not be used in horses intended for human consumption. [24]
Side effects are not common, but the use of acepromazine in stallions should be used with caution (but is not absolutely contraindicated) due to the risk of paraphimosis and priapism. [6]
Acepromazine also lowers blood pressure, and should therefore be used with caution in horses that are experiencing anemia, dehydration, shock, or colic. It should not be used in horses dewormed with piperazine. [23]
Chlorpromazine (CPZ), marketed under the brand names Thorazine and Largactil among others, is an antipsychotic medication. It is primarily used to treat psychotic disorders such as schizophrenia. Other uses include the treatment of bipolar disorder, severe behavioral problems in children including those with attention deficit hyperactivity disorder, nausea and vomiting, anxiety before surgery, and hiccups that do not improve following other measures. It can be given orally, by intramuscular injection, or intravenously.
Perphenazine is a typical antipsychotic drug. Chemically, it is classified as a piperazinyl phenothiazine. Originally marketed in the United States as Trilafon, it has been in clinical use for decades.
Promethazine, sold under the brand name Phenergan among others, is a first-generation antihistamine, sedative, and antiemetic used to treat allergies, insomnia, and nausea. It may also help with some symptoms associated with the common cold and may also be used for sedating people who are agitated or anxious, an effect that has led to some recreational use. Promethazine is taken by mouth (oral), as a rectal suppository, or by injection into a muscle (IM).
Prochlorperazine, formerly sold under the brand name Compazine among others, is a medication used to treat nausea, migraines, schizophrenia, psychosis and anxiety. It is a less preferred medication for anxiety. It may be taken by mouth, rectally, injection into a vein, or injection into a muscle.
Levomepromazine, also known as methotrimeprazine, is a phenothiazine neuroleptic drug. Brand names include Nozinan, Levoprome, Detenler, Hirnamin, Levotomin and Neurocil. It is a low-potency antipsychotic with strong analgesic, hypnotic and antiemetic properties that are primarily used in palliative care.
Xylazine is a structural analog of clonidine and an α2-adrenergic receptor agonist, sold under many trade names worldwide, most notably the Bayer brand name Rompun, as well as Anased, Sedazine and Chanazine.
Chlorprothixene, sold under the brand name Truxal among others, is a typical antipsychotic of the thioxanthene group.
Droperidol is an antidopaminergic drug used as an antiemetic and as an antipsychotic. Droperidol is also often used as a rapid sedative in intensive-care treatment, and where "agitation aggression or violent behavior" are present.
Butorphanol is a morphinan-type synthetic agonist–antagonist opioid analgesic developed by Bristol-Myers. Butorphanol is most closely structurally related to levorphanol. Butorphanol is available as the tartrate salt in injectable, tablet, and intranasal spray formulations. The tablet form is only used in dogs, cats and horses due to low bioavailability in humans.
Cyproheptadine, sold under the brand name Periactin among others, is a first-generation antihistamine with additional anticholinergic, antiserotonergic, and local anesthetic properties.
Propiomazine, sold under the brand name Propavan among others, is an antihistamine which is used to treat insomnia and to produce sedation and relieve anxiety before or during surgery or other procedures and in combination with analgesics as well as during labor. Propiomazine is a phenothiazine, but is not used therapeutically as a neuroleptic because it does not block dopamine receptors well.
Promazine, is used as a short-term add-on treatment for psychomotor agitation. Its approved uses in people is limited, but is used as a tranquilizer in veterinary medicine. It has weak antipsychotic effects but is generally not used to treat psychoses.
Dexmedetomidine, sold under the trade name Precedex among others, is a drug used in humans for sedation. Veterinarians use dexmedetomidine for similar purposes in treating cats, dogs, and horses. It is also used in humans to treat acute agitation associated with schizophrenia or bipolar disorder. It is administered as an injection or intravenous solution or as a buccal or sublingual film.
Azaperone is a pyridinylpiperazine and butyrophenone neuroleptic drug with sedative and antiemetic effects, which is used mainly as a tranquilizer in veterinary medicine. It is uncommonly used in humans as an antipsychotic drug.
Detomidine is an imidazole derivative and α2-adrenergic agonist, used as a large animal sedative, primarily used in horses. It is usually available as the salt detomidine hydrochloride. It is a prescription medication available to veterinarians sold under various trade names.
Veterinary anesthesia is a specialization in the veterinary medicine field dedicated to the proper administration of anesthetic agents to non-human animals to control their consciousness during procedures. A veterinarian or a Registered Veterinary Technician administers these drugs to minimize stress, destructive behavior, and the threat of injury to both the patient and the doctor. The duration of the anesthesia process goes from the time before an animal leaves for the visit to the time after the animal reaches home after the visit, meaning it includes care from both the owner and the veterinary staff. Generally, anesthesia is used for a wider range of circumstances in animals than in people not only due to their inability to cooperate with certain diagnostic or therapeutic procedures, but also due to their species, breed, size, and corresponding anatomy. Veterinary anesthesia includes anesthesia of the major species: dogs, cats, horses, cattle, sheep, goats, and pigs, as well as all other animals requiring veterinary care such as birds, pocket pets, and wildlife.
Maropitant (INN; brand name: Cerenia, used as maropitant citrate (USAN), is a neurokinin-1 (NK1) receptor antagonist developed by Zoetis specifically for the treatment of motion sickness and vomiting in dogs. It was approved by the FDA in 2007, for use in dogs and in 2012, for cats.
Atipamezole, sold under the brand name Antisedan among others, is a synthetic α2 adrenergic receptor antagonist used for the reversal of the sedative and analgesic effects of dexmedetomidine and medetomidine in dogs. Its reversal effect works by competing with the sedative for α2-adrenergic receptors and displacing them. It is mainly used in veterinary medicine, and while it is only licensed for dogs and for intramuscular use, it has been used intravenously, as well as in cats and other animals(intravenous use in cats and dogs is not recommended due to the potential for cardiovascular collapse. This occurs due to profound hypotension caused by reversal of the alpha 1 effects while the reflex bradycardia is still in effect.). There is a low rate of side effects, largely due to atipamezole's high specificity for the α2-adrenergic receptor. Atipamezole has a very quick onset, usually waking an animal up within 5 to 10 minutes.
Barbiturate dependence develops with regular use of barbiturates. This in turn may lead to a need for increasing doses of the drug to get the original desired pharmacological or therapeutic effect. Barbiturate use can lead to both addiction and physical dependence, and as such they have a high potential for excess or non-medical use, however, it does not affect all users. Management of barbiturate dependence involves considering the affected person's age, comorbidity and the pharmacological pathways of barbiturates.