Xylazine

Description

Xylazine is an α2-adrenergic agonist used as a veterinary anaesthetic. In recent years, xylazine has emerged as an adulterant in illicit drugs, especially opioids. Xylazine is known to produce intense sedative effects and skin wounds.

Pharmacology

Xylazine is a potent α2-adrenergic receptor agonist. By activating the α2-adrenergic receptor, xylazine disrupts nerve signals in the part of the nervous system involved in the fight-or-flight response. This produces a strong sedative effect, including slowing down heart rate.

The mechanism of xylazine wounds is still a topic of investigation. Skin popping during subcutaneous injection can result in inflammation and chronic ulceration. Xylazine’s activation of peripheral α2 receptors leads to vasoconstriction (narrowing of blood vessels) which may cause less blood to reach the extremities, where wounds are most commonly found.

Xylazine’s effects usually start 15–30 minutes after administration, and its sedative effects may last for up to 4 hours. Xylazine is metabolised rapidly in the liver by CYP450 enzymes and excreted in urine. Human tolerance to xylazine varies significantly, with fatal doses ranging between 40–2,400 mg.

Due to its nervous system depressant effects, medetomidine in combination with other depressants such as opioids can increase the risk of overdose. In an opioid overdose involving medetomidine, naloxone administration can reverse the opioid effects but the individual may remain heavily sedated.

Harm Reduction

• Carry naloxone: While xylazine’s effects are not reversed by naloxone, it can address opioid-induced respiratory depression in overdose.
• Test your stuff: Many illicit drugs tested in the UK have been found to contain xylazine either alone or in combination with other drugs, and you can’t see this by eye. Find out how to send a sample to WEDINOS for testing here: https://www.wedinos.wales or pick up some xylazine test strips at our Harm Reduction Hub
• Use sterile syringes: Avoid reusing or sharing equipment. You can pick up sterile equipment from our Harm Reduction Hub or your local NSP.
• Ensure any wounds are treated properly: Your NSP can either provide this care or signpost you to the right service.
• Start low, go slow: Take a small amount and wait until you can feel the effects before taking more/anything else
• Try not to use alone: If something goes wrong, someone is there to get help
• Be careful mixing: Mixing xylazine with other depressants increases overdose risk – avoid if you can, otherwise take less of each, as they can increase the effects and risks
• Don’t suddenly stop taking it, or you may start to experience symptoms of withdrawal: these can range from a return of your original symptoms (possibly even worse than before) to totally new symptoms.
• If you have become physically dependent on xylazine, the symptoms of abruptly stopping are likely to be even worse. It’s important to get proper medical advice on how to reduce your intake slowly.
• It’s also possible to become psychologically dependent on the drug (feeling like you need it all the time). If you think this is happening, see your doctor as soon as possible, but don’t suddenly stop taking it.

History

Xylazine was developed by Farbenfabriken Bayer in 1962 as an antihypertensive agent. It was found to depress the central nervous system in human clinical trials, after which further human research was discontinued. Xylazine was instead marketed as a veterinary sedative, becoming one of the most common sedatives used for large animals in the 1970s.

Non-medical use of xylazine became more prominent in the 21st century. Xylazine was first found as an adulterant mixed with heroin in Puerto Rico in the early 2000s, before reaching mainland US in 2006. In 2019, xylazine detections surged in Canada, particularly western provinces like British Columbia. In 2021, xylazine reached Europe in combination with synthetic opioids, and the first xylazine-related death outside North America occurred in July 2023 in England.

Law

• Class C
• Schedule 4 (1)

Possible offences

• Possession
  • Maximum sentence – 2 years/fine/both
• Possession With Intent To Supply
  • Maximum sentence – 14 years/fine/both
• Supply (including being concerned in supply, conspiracy to supply, aggravated supply and offer to supply)
  • Maximum sentence – 14 years/fine/both
• Production
  • Maximum sentence – 14 years/fine/both

In practice maximum sentences are rarely used, for more detailed and accurate information go to our sentencing page.