Episode 90: Fentanyl: Toxicity, Testing and Interpretation

This week on The Tox Lab, we're taking a closer look at fentanyl, exploring its clinical use, toxicological risks, and the analytical challenges associated with detecting and interpreting fentanyl exposure. We begin by examining fentanyl patch-related deaths reported in England, Wales and Northern Ireland, including cases highlighted through Prevention of Future Deaths reports. We discuss how fentanyl patches can contribute to fatal toxicity and consider what these cases can tell us about preventing future deaths. We then turn to the laboratory, exploring fentanyl immunoassay cut-offs and why the concentration used to define a positive result matters. We discuss the importance of understanding and clinically assessing analytical cut-offs in different toxicological scenarios, rather than treating a single threshold as universally applicable. Finally, we examine 4-ANPP, a minor metabolite of fentanyl that is also an important precursor and impurity associated with illicit fentanyl manufacture. We explore whether detecting 4-ANPP could help distinguish between exposure to pharmaceutical fentanyl and illicitly manufactured fentanyl, and consider the challenges in interpreting this marker. Join us as we explore fentanyl toxicity, analytical interpretation, and the challenges of distinguishing different sources of fentanyl exposure, and consider what these findings mean for clinical and forensic toxicology. Hope you enjoy! Links to the papers we discussed: https://bpspubs.onlinelibrary.wiley.com/doi/10.1002/bcp.70525 https://academic.oup.com/jat/article-abstract/50/5/bkag025/8658822?redirectedFrom=fulltext https://academic.oup.com/jat/article-abstract/50/3/bkaf111/8415903?redirectedFrom=fulltext Disclaimer: All opinions are our own. Find us on instagram: @the\_tox\_lab Email us here: thetoxlab@gmail.com Check out our new website: https://thetoxlab.co.uk/ Support us here: https://buymeacoffee.com/thetoxlab