Azaperone
Azaperone (R-1929)
Also known as: Stresnil Β· Suicalm Β· Azaperonum Β· R-1929
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
π NA β North Americaπ EU β Europe
Swine
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Mixing feeder or weanling pigs | 2.2 mg/kg deeply IM | IM | Single dose | β | π NA |
| Aggression (prevention and cure of fighting; including regrouping of piglets, porkers, fattening pigs) | 2 mg/kg (1 mL/20 kg) | IM | Single dose | β | π NA |
| Treatment of aggression in sows | 2 mg/kg (1 mL/20 kg) | IM | Single dose | β | π NA |
| Stress (restlessness, anxiety, etc.) | 1-2 mg/kg (0.5-1 mL/20 kg) | IM | Single dose | β | π NA |
| Transport of boars | 1 mg/kg (0.5 mL/20 kg) | IM | Single dose | β | π NA |
| Transport of weaners | 0.4-2 mg/kg (0.4-1 mL/20 kg) | IM | Single dose | β | π NA |
| Obstetrics | 1 mg/kg (0.5 mL/20 kg) | IM | Single dose | β | π NA |
| As a premed | 1-2 mg/kg (0.5-1 mL/20 kg) | IM | Single dose | β | π NA |
- Mixing feeder or weanling pigs: No longer on US market
- Aggression (prevention and cure of fighting; including regrouping of piglets, porkers, fattening pigs): Given IM directly behind the ear using a long hypodermic needle, perpendicular to the skin.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Azaperone is a potent butyrophenone tranquilizer and neuroleptic agent primarily utilized in veterinary medicine for swine and wildlife management.
- Swine: It is the drug of choice for controlling aggression, especially when mixing or regrouping weanling or feeder pigs, preventing fighting and stress. It is also used for obstetrics and as a preanesthetic.
- Wildlife: Frequently used in combination with butorphanol and medetomidine (known as the BAM protocol) for the immobilization of cervids (e.g., deer).
- Equine: Generally avoided in horses due to adverse reactions including sweating, muscle tremors, panic, CNS excitement, and significant arterial hypotension.
Clinical Pearl: Unlike phenothiazines (e.g., acepromazine), azaperone provides reliable sedation in pigs but lacks analgesic properties. It must be combined with an opioid or local anesthetic for painful procedures.
Mechanism of action
Azaperone exerts its effects primarily through the central nervous system and peripheral vasculature:
- Dopamine (D2) Receptor Antagonism: Blocks D2 receptors in the brain (basal ganglia and limbic system) β produces profound tranquilization, reduced motor activity, and anti-emetic effects.
- Alpha-1 Adrenergic Blockade: Antagonizes peripheral Ξ±1-receptors β causes vasodilation, which can lead to mild to moderate hypotension.
- Thermoregulation: Prevents halothane-induced malignant hyperthermia in susceptible swine by stabilizing thermoregulatory centers.
- Respiratory Effects: Has minimal direct effects on respiration and may inhibit some respiratory depressant actions of general anesthetics.
Safety & warnings
Contraindications
- Intravenous (IV) administration
- Very cold conditions (risk of cardiovascular collapse)
Adverse effects
- Transient salivation
- Piling
- Panting
- Shivering
- Hypotension
- Penis extrusion in boars (at doses >1 mg/kg)
- Hypoventilation and hypoxemia (when used in BAM combo in deer)
Precautions
Do not give IV as a significant excitatory phase may be seen in pigs. Avoid use in very cold conditions as cardiovascular collapse may occur secondary to peripheral vasodilation. Do not exceed dosing recommendations in boars as the drug may cause the penis to be extruded. Because Vietnamese Pot Bellied pigs may have delayed absorption due to sequestration of the drug in body fat, re-dose with extreme caution; deaths have resulted after repeat dosing. Pigs should be left undisturbed for approximately 20 minutes after injection.
Drug interactions
May cause additive CNS depression if used concurrently with butyrophenones.
Monitoring
- Level of sedation
- Cardiovascular status (blood pressure)
Pharmacokinetics
Absorption
Fairly rapid onset of action following IM injections in pigs (5-10 minutes) with a peak effect at approximately 30 minutes post injection.
Distribution
May be sequestered in body fat (notably in Vietnamese Pot Bellied pigs).
Metabolism
Metabolized in the liver.
Elimination
13% excreted in the feces. Practically all the drug is eliminated from the body by 16 hours post-dose.
Overdose
Azaperone overdoses can cause hypotension. Doses >1 mg/kg in boars may cause penis extrusion leading to damage. There is no specific reversal agent for azaperone; treatment should be supportive and symptomatic.
Available products
Formulations
- Injection (40 mg/mL)
- Compounded injection
- BAM combination injection (butorphanol, azaperone, medetomidine)
Veterinary
- Azaperone 40 mg/mL for Injection (Stresnil - UK)
- Compounded azaperone injection (zoopharm.net)
- BAM (butorphanol, azaperone, medetomidine) combination injection (zoopharm.net)
Regulatory status
No regulatory data for: πΊπΈ US Β· πͺπΊ EU Β· π¬π§ UK Β· ππ° HK Β· πΉπΌ TW Β· π―π΅ JP Β· π°π· KR Β· π¦πΊ AU
Storage & stability
Store at controlled room temperature (15-25Β°C) and away from light. Do not store above 25Β°C. Once the vial is opened it should be used within 28 days.
Client information
- Administration: Must be injected deeply into the muscle (IM), typically behind the ear and perpendicular to the skin, or in the back of the ham.
- Environment: After injection, leave the pig completely undisturbed for at least 20 minutes. Disturbing the animal during the onset phase can trigger excitement or panic.
- Group Treatments: When mixing pigs, ensure all animals in the group are treated to prevent untreated pigs from attacking sedated ones.
- What to Expect: You may notice temporary drooling, panting, shivering, or pigs piling on top of each other. This is normal and should pass.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerβs current label.