Synthetic opioids may have caused hundreds more UK deaths than reported

Researchers at King's College London found that nitazene synthetic opioids can degrade in postmortem blood samples, and modelling using national mortality data suggests some UK deaths linked to these drugs may have been undercounted by up to a third.

Researchers at King's College London report that deaths linked to nitazene synthetic opioids may have been undercounted in the UK. Nitazenes are highly potent opioids first developed in the 1950s and are reported as up to 500 times stronger than heroin. The team tested drug persistence under realistic pathology and toxicology sample-handling conditions and then applied their findings to national mortality data. The possibility of missed detections has led the researchers to question the completeness of official figures. Key findings: - Nitazenes are a class of synthetic opioids reported as up to 500 times stronger than heroin. - The National Crime Agency recorded 333 fatalities linked to nitazenes across the UK in 2024. - Laboratory experiments using anaesthetised rats and realistic sample-handling found that on average about 14% of the nitazene present at the time of overdose remained detectable in postmortem blood tests. - Researchers applied modelling to the UK National Programme on Substance Use Mortality data and reported an excess of drug deaths in Birmingham in 2023 by about one third, which they suggest could be explained by non-detection of nitazenes. Summary: If nitazenes are degrading in postmortem samples, official drug-related mortality figures may understate the role these compounds play in UK deaths, which has implications for how data are interpreted and used. Undetermined at this time.