What is Xylazine Hydrochloride used for?

Xylazine is a drug used in veterinary medicine as a sedative with analgesic and muscle relaxant properties. It is used on many different animal species such as cattle, sheep, horses, dogs, cats, deer, rats, and elk to calm and facilitate handling, perform diagnostic and surgical procedures, relieve pain, or act as a local anesthetic. Reports, alerts, and advisories indicate an increased xylazine prevalence as an adulterant in drug of abuse mixtures. This non-narcotic agent was first synthesized in 1962 by the Bayer Company. Xylazine has been studied in humans for its potential use as an analgesic, hypnotic, and anesthetic, but these clinical trials were terminated due to its severe hypotension and central nervous system depressant effects.

Is it legal to use this product？

Xylazine is approved by the U.S. Food and Drug Administration (FDA) for veterinary use only. It is available in liquid solutions at 20, 100, and 300 mg/mL. Typically, this drug is administered either alone or in conjunction with other anesthetics (e.g., ketamine or barbiturates) intravenously, intramuscularly, or orally for sedative and relaxant properties.

What is the pharmacology of this product?

The pharmacology of xylazine is well established in animal species, however, human studies are scarce. Xylazine, acting as an agonist at alpha-2 adrenergic receptors, decreases the release of norepinephrine and dopamine in the central nervous system resulting in effects such as analgesia, sedation, and muscle relaxation. Also, xylazine may have cholinergic, serotonergic, dopaminergic, alpha-1 adrenergic, histaminergic, or opiate receptor mechanisms. Xylazine typically has an onset of effects within a few minutes and lasts up to four hours in animals. Pharmacokinetics between animal species did not vary significantly. The major biotransformed metabolite is 2,6-dimethylaniline (DMA). Phase I metabolism includes dealkylation, oxidization, and hydroxylation. Phenolic metabolites were excreted in the glucuronide or sulfate forms. Hydroxylated metabolites were detected in human urine with overdose cases.

What are the user groups of this product?

Exposure to xylazine is common amongst heroin, fentanyl, and cocaine abusers as xylazine is often used as an adulterant with illicit substances. Exposure cases have included both intentional and accidental dosing.

What is the toxicological reaction of this product?

Reported concentrations of xylazine in humans vary. In non-fatal cases, reported concentrations were from 30 to 4,600 ng/mL with documented toxic effects including blurred vision, disorientation, drowsiness, staggering, coma, bradycardia, respiratory depression, hypotension, miosis, and hyperglycemia. Fatality case reports have documented concentration ranges from a trace amount up to 16,000 ng/mL both as a contributory factor and sole use. Unfortunately, therapeutic, toxic, and lethal concentrations in humans cannot be established because of the overlap of fatal and nonfatal concentrations reported. Higher concentration exposures required medical intervention to treat various symptoms.

What is the medical use of this product?

Xylazine is often used as a sedative, muscle relaxant, and analgesic. It is frequently used in the treatment of tetanus. Xylazine is very similar to drugs such as phenothiazine, tricyclic antidepressants, and clonidine. As an anesthetic, it is typically used in conjunction with ketamine. Xylazine appears to reduce sensitivity to insulin and glucose uptake in humans. Yohimbine, an α2 adrenergic receptor antagonist, has been used to decrease glucose levels to a healthy level. In clinical settings, yohimbine can reverse the adverse effects of xylazine if administered intravenously shortly after xylazine administration.

This product has serious side effects. Do not use it for entertainment.

Xylazine overdose is usually fatal in humans. Because it is used as a drug adulterant, the symptoms caused by the drugs accompanying xylazine administration vary between individuals.

The most common side effects in humans associated with xylazine administration include bradycardia, respiratory depression, hypotension, transient hypertension secondary to vagus nerve stimulation, and other changes in cardiac output. Xylazine significantly decreases heart rate in animals that are not premedicated with medications that have anticholinergic effects. The decrease in heart rate directly impacts aortic flow. Bradycardia caused by xylazine administration is effectively prevented by the administration of atropine or glycopyrrolate. Arrhythmias associated with xylazine include other symptoms such as sinoatrial block, atrioventricular block, A-V dissociation, and sinus arrhythmia.

Xylazine administration can lead to diabetes mellitus and hyperglycemia. Other possible side effects that can occur are areflexia, asthenia, ataxia, blurred vision, disorientation, dizziness, drowsiness, dysarthria, dysmetria, fainting, hyporeflexia, slurred speech, somnolence, staggering, coma, apnea, shallow breathing, sleepiness, premature ventricular contraction, tachycardia, miosis, and dry mouth. Rarely, do hypotonia, dry mouth, urinary incontinence, and nonspecific electrocardiographic ST-segment changes occur. It has been reported that the duration of symptoms after the human overdose is 8 to 72 hours. Further research is necessary to categorize the side effects that occur when xylazine is used in conjunction with heroin and cocaine.

Chronic use is reported to be associated with physical deterioration, dependence, abscesses, and skin ulceration, which can be physically debilitating and painful. Hypertension followed by hypotension, bradycardia, and respiratory depression lower tissue oxygenation in the skin. Thus, chronic use of xylazine can progress the skin oxygenation deficit, leading to severe skin ulceration. Lower skin oxygenation is associated with impaired healing of wounds and a higher chance of infection. The ulcers may have a characteristic odor and ooze pus. In severe cases, amputations must be performed on the affected extremities.