Xylazine now in UK drug market, warn King’s College researchers 

The powerful non-opioid tranquiliser xylazine has infiltrated the UK’s drug market and is ‘not limited to heroin supplies’, according to a new report by researchers at King’s College London (KCL). 

the UK’s first xylazine death – a 43-year-old man in Solihull - Map of Solihull
The UK’s first xylazine death was a 43-year-old man in Solihull.

The drug, known in the US as ‘tranq’ or ‘tranq dope’ – especially when mixed with fentanyl or heroin – has been associated with dangerous side effects such as large open skin ulcers. As xylazine is not an opioid its own effects cannot be reversed by naloxone in the case of an overdose, although it is frequently used with opioids. A sedative, painkiller and muscle relaxant, it is used in veterinary medicine as a tranquiliser for animals and can dangerously lower breathing and heart rates in humans. 

KCL researchers contacted all toxicology labs in the UK to collate evidence of xylazine detections in biological samples. They found the presence of the drug in 16 people, 11 of which cases were fatalities. Many of the samples dated from last year, while May 2022 saw the UK’s first xylazine death – a 43-year-old man in Solihull. 

While xylazine is usually mixed with opioids it has also been detected ‘alongside stimulant drugs such as cocaine, and found in items sold as counterfeit codeine and diazepam tablets and even THC vapes’, says KCL. This means a far wider population than people who use heroin will be exposed, warns the report, which is published in the journal Addiction

In February, the ACMD wrote to the government recommending that although there was no ‘evidence of intended use’ of xylazine in the UK, given its acute toxicity – and ‘similarity to the enhanced toxicity seen when benzodiazepines are co-used with opioids’ – it should be made a class C drug. 

‘We now know that xylazine has penetrated the UK’s illicit drug market,’ said the report’s senior author Dr Caroline Copeland from KCL’s School of Cancer and Pharmaceutical Sciences. ‘We also know that most people who buy heroin will not intend to buy xylazine and this combination increases the risk of overdose. Xylazine was designated an “emerging threat” to the United States and this public health threat is a growing concern for the UK.

There are three simple measures the UK can introduce to prevent the epidemic of xylazine use that has emerged in the USA. Cheap xylazine test strips should be made available, healthcare providers need to be aware of the signs that chronic skin ulcers are due to xylazine use, and pathologists and coroners should specifically request toxicology testing for xylazine in relevant cases to understand the true prevalence of the drug.’

‘Copeland and her colleagues bring important new information about the appearance of a new drug, xylazine, as a co-drug added to illicit heroin and also apparently as a novel drug on its own,’ commented Professor Sir John Strang.

‘This has required integration of data from different sources (from case reports, from national data-sets and from forensic toxicology) and collaboration across different disciplines and different universities alongside data collection organisations or law enforcement. Copeland and colleagues also identify possible changes in public health planning and law enforcement – a good illustration of how science can inform public policy and practice and enable valuable impact.’ 

Report at https://onlinelibrary.wiley.com/doi/full/10.1111/add.16466

ACMD: use and harms of xylazine, medetomidine and detomidine at https://www.gov.uk/government/publications/use-and-harms-of-xylazine-medetomidine-and-detomidine

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