Slow Dissociation of Nitazenes from the 𝜇-Opioid Receptor Underlies the Challenge of Overdose Reversal

Slow Dissociation of Nitazenes from the 𝜇-Opioid Receptor Underlies the Challenge of Overdose Reversal | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL British Journal of Pharmacology This is a preprint and has not been peer reviewed. Data may be preliminary. 13 May 2026 V1 Latest version Share on Slow Dissociation of Nitazenes from the 𝜇-Opioid Receptor Underlies the Challenge of Overdose Reversal Authors : Joseph Clayton [email protected] , Laura B. Kozell [email protected] , A.J. Eshleman [email protected] , Shelley H. Bloom [email protected] , William E. Schutzer [email protected] , Atheir I. Abbas [email protected] , Lidiya Stavitskaya [email protected] , and Jana Shen 0000-0002-3234-0769 [email protected] Authors Info & Affiliations https://doi.org/10.22541/authorea.15003265/v1 Under Review British Journal of Pharmacology Peer review timeline 54 views 26 downloads Contents Abstract Graphical Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Nitazenes are driving a wave of overdose deaths in the United States and Europe and of-ten require additional doses of naloxone to reverse. To understand the molecular basis, we conducted a joint experimental and simulation study of three common nitazenes, eto-, etodes-, and protonitazene. Radioligand experiments demonstrated that all three nitazenes display higher receptor affinity and longer dissociation half-lives than fentanyl. Notably, protonitazene dissociates slower than carfentanil and its displacement requires fourfold higher antagonist con-centrations. The observed trend in nitazene half-lives is recapitulated by molecular dynamics simulations, which suggest that kinetics is controlled by specific interactions with two receptor subpockets. A newly published cryo-EM structure of fluetonitazene- 𝜇OR complex confirms the predicted interactions, including a 𝜋-hole bond between the nitro group and Tyr 1.39, a residue recently shown to modulate 𝜇OR signaling bias. Our findings suggest slow receptor dissocia-tion as a key factor challenging overdose reversal. The mechanistic insights have implications for understanding opioid toxicity and designing more effective countermeasures. Graphical Abstract Image (toc.pdf) is missing or otherwise invalid. Supplementary Material File (nitazenes_kinetics_si.pdf) nitazenes_kinetics_si Download 853.94 KB Information & Authors Information Version history V1 Version 1 13 May 2026 Peer review timeline Under Review British Journal of Pharmacology 13 May 2026 Review Complete 13 May 2026 Submission Checks Completed Collection British Journal of Pharmacology Authors Affiliations Joseph Clayton [email protected] View all articles by this author Laura B. Kozell [email protected] View all articles by this author A.J. Eshleman [email protected] View all articles by this author Shelley H. Bloom [email protected] View all articles by this author William E. Schutzer [email protected] View all articles by this author Atheir I. Abbas [email protected] View all articles by this author Lidiya Stavitskaya [email protected] University of Maryland Baltimore School of Pharmacy, Baltimore, United States, 21201 View all articles by this author Jana Shen 0000-0002-3234-0769 [email protected] University of Maryland Baltimore School of Pharmacy, Baltimore, United States, 21201 View all articles by this author Metrics & Citations Metrics Article Usage 54 views 26 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Joseph Clayton, Laura B. Kozell, A.J. Eshleman, et al. Slow Dissociation of Nitazenes from the 𝜇-Opioid Receptor Underlies the Challenge of Overdose Reversal. Authorea . 13 May 2026. DOI: https://doi.org/10.22541/authorea.15003265/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. 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