Deaths caused by a synthetic opioid that is hundreds of times stronger than heroin may have been underestimated by up to a third across the UK, according to research.
Nitazenes are a class of synthetic opioids that are extremely potent, and up to 500 times stronger than heroin. They were manufactured originally as a painkiller in the 1950s but their development was halted due to their extreme potencies resulting in a high risk of addiction.
In 2024, the National Crime Agency (NCA) reported that 333 fatalities across the UK were linked to the drug. However, researchers at King’s College London say that the true number of deaths may have been underreported, due to concerns that samples of the drug are likely being missed in postmortem toxicology tests.
The study involved researchers testing samples from rats that had been anaesthetised with the drug, and finding that on average only 14% of the nitazene present at the time of overdose was still present when tested under real-world pathology and toxicology sample-handling conditions.
After this, the academics applied modelling to data from the UK National Programme on Substance Use Mortality (NPSUM) to reveal that there was an excess of drug deaths in Birmingham in 2023 by a third. The researchers concluded that an explanation for the discrepancy could be due to the non-detection of nitazene by toxicologists in these instances.
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“As a significant proportion of deaths are likely being missed, this has serious implications for the accuracy of drug-related mortality data, which are used to inform the design and funding of harm reduction strategies,” said Dr Caroline Copeland, a senior lecturer in pharmacology and toxicology at King’s and lead author of the study.
She added: “If nitazenes are degrading in postmortem blood samples, then we are almost certainly undercounting the true number of deaths that they are causing. That means we’re trying to tackle a crisis using incomplete data. When we don’t measure a problem properly, we don’t design the right interventions – and the inevitable consequence is that preventable deaths will continue.
“Behind this undercount are people dying suddenly from extremely potent opioids, families left without answers, and communities facing a growing but largely hidden toll.”
Synthetic opioids have become an increasing public health concern in recent years. In Scotland, health experts have warned that the country faces a fresh drug deaths crisis due to highly potent synthetic opioids already linked to more than 100 fatalities.
Mike Trace, the chief executive of the Forward Trust and co-creator of the UK’s first national drug strategy, said: “The extreme potency of nitazenes has clearly contributed to rising overdose and death rates amongst people who use drugs. This research shows the official numbers are probably underestimates, supporting our calls for the government to be braver in rolling out drug testing and overdose prevention measures to save lives.
“With over 17,000 people per year across the UK dying from drug or alcohol-related causes, we cannot afford to be hesitant in providing lifesaving health services to people taking illegal drugs.
A government spokesperson said: “Every death from the misuse of drugs is a tragedy. This government is committed to reducing drug-related deaths and supporting more people into recovery to live healthier, longer lives.
“We remain on high alert to emerging drug threats, working closely with health services and policing partners to stay ahead of criminals who target our communities. Border Force has also become the first agency in the world to use specially trained dogs to detect both deadly fentanyl and nitazenes.”
