Xylazine
[CAS# 7361-61-7]

Identification

• Classification: API >> Anesthetic agents >> General anesthetics
• Name: Xylazine
• Synonyms: N-(2,6-Dimethylphenyl)-5,6-dihydro-4H-1,3-thiazin-2-amine
• Molecular Formula: C₁₂H₁₆N₂S
• Molecular Weight: 220.33
• CAS Registry Number: 7361-61-7
• EC Number: 230-902-1
• SMILES: CC1=C(C(=CC=C1)C)NC2=NCCCS2

Properties

• Solubility: 4.776 mg/L (25 °C water)
• Density: 1.2±0.1 g/cm³, Calc.^*
• Index of Refraction: 1.611, Calc.^*
• Melting point: 120.08 °C
• Boiling Point: 334.2±52.0 °C (760 mmHg), Calc.^*, 337.66 °C
• Flash Point: 155.9±30.7 °C, Calc.^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS06 Danger
• Risk Statements: H301
• Safety Statements: P264-P270-P301+P310+P330-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	3	H301
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	3	H311
Acute toxicity	Acute Tox.	4	H332
Acute toxicity	Acute Tox.	2	H330
Acute toxicity	Acute Tox.	4	H312
Acute toxicity	Acute Tox.	3	H331
Acute toxicity	Acute Tox.	4	H302

• Transport Information: UN 2811

Discovery and Applications

VXylazine, a veterinary sedative and analgesic, was first synthesized in the early 1960s by Bayer AG in Germany. Initially developed as an antihypertensive agent, its potent sedative and analgesic properties were soon recognized, leading to its application in veterinary medicine. Xylazine belongs to the class of alpha-2 adrenergic agonists, working by stimulating alpha-2 receptors in the central nervous system to produce sedation, analgesia, and muscle relaxation. The discovery of xylazine provided veterinarians with an effective and versatile tool for the sedation and management of pain in animals, particularly in large animals like horses and cattle.

Xylazine is primarily used as a sedative in veterinary medicine. Its ability to induce a calm and relaxed state makes it invaluable for procedures that require immobilization or reduced anxiety, such as diagnostic imaging, minor surgical procedures, and handling of fractious animals. The sedative effects of xylazine help ensure the safety of both the animal and the veterinary staff during these procedures.

Beyond sedation, xylazine is effective as an analgesic, providing pain relief for various conditions and procedures. It is often used in combination with other anesthetics or analgesics to enhance pain management protocols, particularly during and after surgical interventions. This makes it a key component in multimodal pain management strategies in veterinary practice.

Xylazine induces muscle relaxation, which is particularly beneficial during surgeries and certain diagnostic procedures where muscle rigidity can interfere with the process. Its muscle relaxant properties also aid in the treatment of muscle spasms and other conditions requiring muscle relaxation.

Xylazine is frequently used in combination with other drugs to achieve balanced anesthesia and analgesia. For instance, it is often paired with ketamine to produce a reliable and effective anesthetic protocol, providing both sedation and pain relief. This combination is widely used in various veterinary surgical procedures, particularly in large animals.

Xylazine's effects on the central nervous system make it a useful tool in research settings. It is used to study the physiology of sedation, pain, and muscle relaxation in animals, contributing to the understanding of these processes and the development of new anesthetic and analgesic agents. Additionally, xylazine is used in animal models to investigate various diseases and treatment outcomes.

Despite its widespread use, xylazine must be used with caution due to potential side effects such as respiratory depression, bradycardia, and hypotension. Careful dosing and monitoring are essential to minimize these risks. Additionally, xylazine's potential for abuse and misuse has raised concerns, leading to increased regulation and control in some regions.

References

2025. Rational hapten design, antibody preparation, and immunoassay development for rapid screening xylazine in biological samples. Food Chemistry.
DOI: 10.1016/j.foodchem.2024.142054

1997. Effect of Anesthesia on Cerebral Tissue Oxygen and Cardiopulmonary Parameters in Rats. Oxygen Transport to Tissue XVIII.
DOI: 10.1007/978-1-4615-5865-1_5

1999. Effects of Ketamine/Xylazine and Pentobarbital Anesthesia on Cerebral Tissue Oxygen Tension, Blood Pressure, and Arterial Blood Gas in Rats. Oxygen Transport to Tissue XXI.
DOI: 10.1007/978-1-4615-4717-4_23