[성분] 아세프로마진 (Acepromazine)

상세 약물 자료

Pharmacology and mechanism of action

Phenothiazine tranquilizer and sedative. Acepromazine inhibits central dopaminergic receptors to produce sedation and tranquilization. Acepromazine also has antimuscarinic action and blocks norepinephrine at adrenergic receptors (e.g., alpha-receptors). Because of the blockade of alpha-receptors on vascular smooth muscle, it also produces vasodilation. When administered as an anesthetic adjunct, it may produce a decrease in vascular resistance and lower blood pressure, but usually does not decrease cardiac output. In horses, IV administration significantly increases the blood flow through digital arteries and laminae.

Indications and clinical uses

Acepromazine is used as a sedative, a tranquilizer, a preanesthetic, and an anesthetic adjunct. In small animals, duration of sedation can occur within 10 minutes and have a 4-6 hour duration. In small animals, acepromazine can produce antiemetic effects. For some indications, the administration also produces vasodilation. In horses for treatment of laminitis, it has increased the arterial digital blood flow after a dose of 0.02-0.06 mg/kg.

Precautionary information

Adverse reactions and side effects

Sedation and ataxia are common side effects. Extrapyramidal effects (involuntary muscle movements), twitching, dystonia, or parkinsonlike effects are rare but are possible with the administration of phenothiazines to animals. Phenothiazines may produce excessive vagal tone in some animals. This may be especially prominent in brachycephalic breeds. Administration of atropine may be used to treat the signs of high vagal tone. Because of alpha-adrenergic antagonism, hypotension is possible in animals. In horses, persistent penile prolapse has been reported from use. This effect in horses is unpredictable. Some resources indicate that it is dose-dependent with increased likelihood as the dose is increased from 0.01 mg/kg to 0.1 mg/kg IV. The duration of penile prolapse in horses may be as long as 4 hours with high doses. In rare cases, penile prolapse can lead to permanent paraphimosis. The mechanism is unknown but may be caused by the alpha-adrenergic blockade induced by acepromazine.

Contraindications and precautions

It is often stated in veterinary literature that acepromazine may increase risk of seizures in animals and it should be administered cautiously in animals that are prone to seizures. However, a risk of seizures in animals from administration of acepromazine may not be as great as was once thought. Seizures were not reported to be a clinical problem in retrospective studies of patients who had them. Seizures were not reported in studies in which animals prone to seizures were anesthetized and administered acepromazine as an anesthetic adjunct.

Do not use in animals that have problems with dystonia or that have had extrapyramidal effects from use of phenothiazines.

Phenothiazines can cause hypotension (via alpha-receptor blockade); therefore use cautiously with other hypotensive drugs or in conditions that may exacerbate hypotension. When administered as a pre-anesthetic to dogs (0.05 mg/kg) it induces moderate hypotension, but does not affect cardiac output significantly.

In pregnancy it produced only minor reduction in blood flow and oxygen delivery to the fetus when used in late pregnancy in cows.

Drug interactions

Acepromazine may potentiate other drugs that cause vasodilation. Acepromazine may increase the risk of seizures if administered with other drugs that lower seizure threshold, but this may not be as much of a risk as was once thought. Acepromazine has been used to sedate dogs for glucose tolerance testing (0.1 mg/kg), without adversely affecting the results.

Instructions for use

Acepromazine can be administered PO, IV, or IM. When used with general anesthetics, lower doses of general anesthetics can be used, especially when administering barbiturates and inhalant anesthetics. Clinical signs from acepromazine administration are most prominent during the first 3-4 hours after administration, but may persist for 7 hours.

Patient monitoring and laboratory tests

Monitor blood pressure in animals susceptible to hypotension. Acepromazine does not affect adrenal function testing in dogs.

Formulations

• Acepromazine is available in 5-, 10-, and 25-mg tablets and in a 10-mg/mL injection.
• Acepromazine oral granules and powder are available in Canada.

Stability and storage

Store in a tightly sealed container, protected from light, and at room temperature. Stability of compounded formulations has not been investigated.

Small animal dosage

Dogs

• 0.025-0.1 mg/kg IM, IV, or SQ in a single dose (most common is 0.025 mg/kg). Do not exceed 3 mg total in dogs.
• Sedation: 0.5-2.2 mg/kg q6-8h PO.

Cats

• 0.025-0.1 mg/kg IM, IV, or SQ in a single dose.
• Sedation: 1.1-2.2 mg/kg q6-8h PO.

Large animal dosage

Horses

• 0.04-0.1 mg/kg IM, q 6-12h, but frequent dosing is not recommended, and an interval of 36-48 hours between doses is recommended. For perioperative use, 0.01-0.05 mg/kg, IM, SQ, or IV.

Cattle

• 0.13-0.26 mg/kg PO, 0.03-0.1 mg/kg IM, or 0.01-0.02 mg/kg IV.

Pigs

• Adult: 0.03-0.2 mg/kg IV, IM, SQ (single dose).

Regulatory information

Withdrawal times: There are no withdrawal times established in the US. It has been estimated that for extralabel use, establish a withdrawal time of at least 7 days for meat and 48 hours for milk.

Canada: 7 days for meat; 48 hours for milk.

RCI Classification: 3

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