The review describes fentanyl and its analogs as new synthetic opioids and the possibilities of their identification and determination using electrochemical methods (e.g., voltammetry, potentiometry, electrochemiluminescence) and electrochemical methods combined with various separation methods. The review also covers the analysis of new synthetic opioids, their parent compounds, and corresponding metabolites in body fluids, such as urine, blood, serum, and plasma, necessary for a fast and accurate diagnosis of intoxication. Identifying and quantifying these addictive and illicit substances and their metabolites is necessary for clinical, toxicological, and forensic purposes. As a reaction to the growing number of new synthetic opioid intoxications and increasing fatalities observed over the past ten years, we provide thorough background for developing new biosensors, screen-printed electrodes, or other point-of-care devices.

Department of Analytical Chemistry Faculty of Science Palacký University in Olomouc 17 Listopadu 12 771 46 Olomouc Czech Republic

J Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences Dolejškova 3 182 23 Prague Czech Republic

UNESCO Laboratory of Environmental Electrochemistry Department of Analytical Chemistry Faculty of Science Charles University Prague Albertov 6 128 43 Prague Czech Republic

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Jullie D., Gondin A.B., von Zastrow M., Canals M. Opioid pharmacology under the microscope. Mol. Pharmacol. 2020;98:425–432. doi: 10.1124/mol.119.119321. PubMed DOI PMC

Carli M., Donnini S., Pellegrini C., Coppi E., Bocci G. Opioid receptors beyond pain control: The role in cancer pathology and the debated importance of their pharmacological modulation. Pharmacol. Res. 2020;159:104938. doi: 10.1016/j.phrs.2020.104938. PubMed DOI

Sharma A.K., Nareda M., Aziz S., Sharma S., Garg S.K. Fentanyl—A potent opioid analgesic: A review. J. Dev. Drugs. 2016;5:3. doi: 10.4172/2329-6631.1000162. DOI

Smith H.S. Opioid metabolism. Mayo Clin. Proc. 2009;84:613–624. doi: 10.1016/S0025-6196(11)60750-7. PubMed DOI PMC

UNODC Fentanyl and Its Analogues—50 Years on. [(accessed on 19 October 2020)]. Available online: https://www.unodc.org/documents/scientific/Global_SMART_Update_17_web.pdf.

UNODC The Challenge of the New Psychoactive Substances. [(accessed on 19 October 2020)]. Available online: https://www.unodc.org/documents/scientific/NPS_2013_SMART.pdf.

UNODC Nps. New Psychoactive Substances. [(accessed on 19 October 2020)]. Available online: https://www.unodc.org/documents/drugs/printmaterials2013/NPS_leaflet/WDC13_NPS_leaflet_EN_LORES.pdf.

Weedn V.W., Zaney M.E., McCord B., Lurie I., Baker A. Fentanyl-related substance scheduling as an effective drug control strategy. J. Forensic Sci. 2021;66:1186–1200. doi: 10.1111/1556-4029.14712. PubMed DOI PMC

Elbardisy H.M., Foster C.W., Cumba L., Antonides L.H., Gilbert N., Schofield C.J., Belal T.S., Talaat W., Sutcliffe O.B., Daabees H.G., et al. Analytical determination of heroin, fentanyl and fentalogues using high-performance liquid chromatography with diode array and amperometric detection. Anal. Met. 2019;11:1053–1063. doi: 10.1039/C9AY00009G. DOI

Peng P.W.H., Sandler A.N. A review of the use of fentanyl analgesia in the management of acute pain in adults. Anesthesiology. 1999;90:576–599. doi: 10.1097/00000542-199902000-00034. PubMed DOI

Ahmed S.R., Chand R., Kumar S., Mittal N., Srinivasan S., Rajabzadeh A.R. Recent biosensing advances in the rapid detection of illicit drugs. TrAC–Trends Anal. Chem. 2020;131:116006. doi: 10.1016/j.trac.2020.116006. DOI

Bazley M.M., Logan M., Baxter C., Robertson A.A.B., Blanchfield J.T. Decontamination of fentanyl and fentanyl analogues in field and laboratory settings: A review of fentanyl degradation. Aust. J. Chem. 2020;73:868–879. doi: 10.1071/Ch19669. DOI

WHO Opioid Overdose. [(accessed on 19 October 2020)]. Available online: https://www.who.int/news-room/fact-sheets/detail/opioid-overdose.

Jannetto P.J., Helander A., Garg U., Janis G.C., Goldberger B., Ketha H. The fentanyl epidemic and evolution of fentanyl analogs in the united states and the european union. Clin. Chem. 2019;65:242–253. doi: 10.1373/clinchem.2017.281626. PubMed DOI

Zanfrognini B., Pigani L., Zanardi C. Recent advances in the direct electrochemical detection of drugs of abuse. J. Solid State Electrochem. 2020;24:2603–2616. doi: 10.1007/s10008-020-04686-z. DOI

Manchikanti L., Vanaparthy R., Atluri S., Sachdeva H., Kaye A.D., Hirsch J.A. Covid-19 and the opioid epidemic: Two public health emergencies that intersect with chronic pain. Pain Ther. 2021;10:269–286. doi: 10.1007/s40122-021-00243-2. PubMed DOI PMC

Niles J.K., Gudin J., Radcliff J., Kaufman H.W. The opioid epidemic within the COVID-19 pandemic: Drug testing in 2020. Popul. Health Manag. 2021;24:S43–S51. doi: 10.1089/pop.2020.0230. PubMed DOI PMC

Glasscott M.W., Vannoy K.J., Iresh Fernando P.U.A., Kosgei G.K., Moores L.C., Dick J.E. Electrochemical sensors for the detection of fentanyl and its analogs: Foundations and recent advances. TrAC–Trends Anal. Chem. 2020;132:116037. doi: 10.1016/j.trac.2020.116037. DOI

TIC . Toxicological Information Center (Czech Republic)—Database “Evidence”. TIC; Hong Kong, China: 2021.

Gozdzialski L., Ramsay M., Larnder A., Wallace B., Hore D.K. Fentanyl detection and quantification using portable Raman spectroscopy in community drug checking. J. Raman Spectrosc. 2021;52:1308–1316. doi: 10.1002/jrs.6133. DOI

Kuo Y.F., Baillargeon J., Raji M.A. Overdose deaths from nonprescribed prescription opioids, heroin, and other synthetic opioids in medicare beneficiaries. J. Subst. Abuse Treat. 2021;124:108282. doi: 10.1016/j.jsat.2021.108282. PubMed DOI PMC

Zawilska J.B., Kuczynska K., Kosmal W., Markiewicz K., Adamowicz P. Carfentanil—From an animal anesthetic to a deadly illicit drug. Forensic Sci. Int. 2021;320:110715. doi: 10.1016/j.forsciint.2021.110715. PubMed DOI

Uuskula A., Talu A., Vorobjov S., Salekesin M., Rannap J., Lemsalu L., Jarlais D.D. The fentanyl epidemic in Estonia: Factors in its evolution and opportunities for a comprehensive public health response, a scoping review. Int. J. Drug Policy. 2020;81:102757. doi: 10.1016/j.drugpo.2020.102757. PubMed DOI PMC

Wilson N.G., Raveendran J., Docoslis A. Portable identification of fentanyl analogues in drugs using surface-enhanced Raman scattering. Sens. Actuat. B-Chem. 2021;330:129303. doi: 10.1016/j.snb.2020.129303. DOI

Smialek J.E., Levine B., Chin L., Wu S.C., Jenkins A.J. A fentanyl epidemic in maryland 1992. J. Forensic Sci. 1994;39:159–164. doi: 10.1520/JFS13581J. PubMed DOI

Armenian P., Vo K.T., Barr-Walker J., Lynch K.L. Fentanyl, fentanyl analogs and novel synthetic opioids: A comprehensive review. Neuropharmacology. 2018;134:121–132. doi: 10.1016/j.neuropharm.2017.10.016. PubMed DOI

Fields M.D., Abate M.A., Hu L., Long D.L., Blommel M.L., Haikal N.A., Kraner J.C. Parent and metabolite opioid drug concentrations in unintentional deaths involving opioid and benzodiazepine combinations. J. Forensic Sci. 2015;60:950–956. doi: 10.1111/1556-4029.12807. PubMed DOI PMC

Janssen P.A. 1-aralkyl-4-(N-aryl-carbonyl amino)-Piperidines and Related Compounds. no. 5100903a. U.S. Patent. 1965 January 5;

Wilde M., Pichini S., Pacifici R., Tagliabracci A., Busardo F.P., Auwarter V., Solimini R. Metabolic pathways and potencies of new fentanyl analogs. Front. Pharmacol. 2019;10:238. doi: 10.3389/fphar.2019.00238. PubMed DOI PMC

Comer S.D., Cahill C.M. Fentanyl: Receptor pharmacology, abuse potential, and implications for treatment. Neurosci. Biobehav. Rev. 2019;106:49–57. doi: 10.1016/j.neubiorev.2018.12.005. PubMed DOI PMC

Algren D.A., Monteilh C.P., Punja M., Schier J.G., Belson M., Hepler B.R., Schmidt C.J., Miller C.E., Patel M., Paulozzi L.J., et al. Fentanyl-associated fatalities among illicit drug users in Wayne County, Michigan (July 2005–May 2006) J. Med. Toxicol. 2013;9:106–115. doi: 10.1007/s13181-012-0285-4. PubMed DOI PMC

Roy S.D., Flynn G.L. Solubility behavior of narcotic analgesics in aqueous-media–solubilities and dissociation-constants of morphine, fentanyl, and sufentanil. Pharm. Res. 1989;6:147–151. doi: 10.1023/A:1015932610010. PubMed DOI

Moffat A.C., Osselton M.D., Widdop B. Clarke’s Isolation and Identification of Drugs in Pharmaceuticals, Body Fluids, and Post-Mortem Material. 4th ed. Pharmaceutical Press; London, UK: 2011.

Misailidi N., Athanaselis S., Nikolaou P., Katselou M., Dotsikas Y., Spiliopoulou C., Papoutsis I. A gc-ms method for the determination of furanylfentanyl and ocfentanil in whole blood with full validation. Forensic Toxicol. 2019;37:238–244. doi: 10.1007/s11419-018-0449-2. PubMed DOI PMC

Vuckovic S., Prostran M., Ivanovic M., Dosen-Micovic L., Todorovic Z., Nesic Z., Stojanovic R., Divac N., Mikovic Z. Fentanyl analogs: Structure–activity–relationship study. Curr. Med. Chem. 2009;16:2468–2474. doi: 10.2174/092986709788682074. PubMed DOI

Baselt R.C. Disposition of Toxic Drugs and Chemicals in Man. 2nd ed. Biomedical Publications; Davis, CA, USA: 1982.

Thurlkill R.L., Cross D.A., Scholtz J.M., Pace C.N. Pka of fentanyl varies with temperature: Implications for acid-base management during extremes of body temperature. J. Cardiothorac. Vasc. Anesth. 2005;19:759–762. doi: 10.1053/j.jvca.2004.11.039. PubMed DOI

Meuldermans W.E.G., Hurkmans R.M.A., Heykants J.J.P. Plasma-protein binding and distribution of fentanyl, sufentanil, alfentanil and lofentanil in blood. Arch. Int. Pharmacodyn. Ther. 1982;257:4–19. PubMed

Albrecht J. Master’s Thesis. Palacky University in Olomouc; Olomouc, Czech Republic: 2019. Study of electrochemical transformations of new designer drugs.

Bergh M.S.S., Bogen I.L., Nerem E., Wohlfarth A., Wilson S.R., Oiestad A.M.L. Discovering the major metabolites of the three novel fentanyl analogues 3-methylcrotonylfentanyl, furanylbenzylfentanyl, and 4-fluorocyclopropylbenzylfentanyl for forensic case work. Forensic Toxicol. 2021;39:167–178. doi: 10.1007/s11419-020-00560-9. DOI

DEA Controlled Substances. [(accessed on 19 October 2020)]; Available online: https://www.deadiversion.usdoj.gov/schedules/orangebook/c_cs_alpha.pdf.

Labroo R.B., Paine M.F., Thummel K.E., Kharasch E.D. Fentanyl metabolism by human hepatic and intestinal cytochrome p450 3a4: Implications for interindividual variability in disposition, efficacy, and drug interactions. Drug Metab. Dispos. 1997;25:1072–1080. PubMed

Burkle H., Dunbar S., VanAken H. Remifentanil: A novel, short-acting, mu-opioid. Anesth. Analg. 1996;83:646–651. doi: 10.1213/00000539-199609000-00038. PubMed DOI

Henkel E., Vella R., Behan K., Austin D., Kruger P., Fenning A. The effect of concentration, reconstitution solution and ph on the stability of a remifentanil hydrochloride and propofol admixture for simultaneous co-infusion. BMC Anesthesiol. 2020;20:283. doi: 10.1186/s12871-020-01194-5. PubMed DOI PMC

Feasel M.G., Wohlfarth A., Nilles J.M., Pang S.K., Kristovich R.L., Huestis M.A. Metabolism of carfentanil, an ultra-potent opioid, in human liver microsomes and human hepatocytes by high-resolution mass spectrometry. AAPS J. 2016;18:1489–1499. doi: 10.1208/s12248-016-9963-5. PubMed DOI

Watanabe S. Ph.D. Thesis. University of Technology; Sydney, Australia: 2018. Metabolic Study of New Psychoactive Substances.

Watanabe S., Vikingsson S., Roman M., Green H., Kronstrand R., Wohlfarth A. In vitro and in vivo metabolite identification studies for the new synthetic opioids acetylfentanyl, acrylfentanyl, furanylfentanyl, and 4-fluoro-isobutyrylfentanyl. AAPS J. 2017;19:1102–1122. doi: 10.1208/s12248-017-0070-z. PubMed DOI

Staeheli S.N., Baumgartner M.R., Gauthier S., Gascho D., Jarmer J., Kraemer T., Steuer A.E. Time-dependent postmortem redistribution of butyrfentanyl and its metabolites in blood and alternative matrices in a case of butyrfentanyl intoxication. Forensic Sci. Int. 2016;266:170–177. doi: 10.1016/j.forsciint.2016.05.034. PubMed DOI

Sohouli E., Keihan A.H., Shahdost-fard F., Naghian E., Plonska-Brzezinska M.E., Rahimi-Nasrabadi M., Ahmadi F. A glassy carbon electrode modified with carbon nanoonions for electrochemical determination of fentanyl. Mater. Sci. Eng. C Mater. Biol. Appl. 2020;110:110684. doi: 10.1016/j.msec.2020.110684. PubMed DOI

Vikingsson S., Rautio T., Wallgren J., Astrand A., Watanabe S., Dahlen J., Wohlfarth A., Konradsson P., Wu X.Y., Kronstrand R., et al. Lc-qtof-ms identification of major urinary cyclopropylfentanyl metabolites using synthesized standards. J. Anal. Toxicol. 2019;43:607–614. doi: 10.1093/jat/bkz057. PubMed DOI PMC

Gampfer T.M., Wagmann L., Park Y.M., Cannaert A., Herrmann J., Fischmann S., Westphal F., Muller R., Stove C.P., Meyer M.R. Toxicokinetics and toxicodynamics of the fentanyl homologs cyclopropanoyl-1-benzyl-4′-fluoro-4-anilinopiperidine and furanoyl-1-benzyl-4-anilinopiperidine. Arch. Toxicol. 2020;94:2009–2025. doi: 10.1007/s00204-020-02726-1. PubMed DOI PMC

Shaabani N., Chan N.W.C., Jemere A.B. A molecularly imprinted sol-gel electrochemical sensor for naloxone determination. Nanomaterials. 2021;11:631. doi: 10.3390/nano11030631. PubMed DOI PMC

Marchei E., Pacifici R., Mannocchi G., Marinelli E., Busardo F.P., Pichini S. New synthetic opioids in biological and non-biological matrices: A review of current analytical methods. TrAC Trends Anal. Chem. 2018;102:1–15. doi: 10.1016/j.trac.2018.01.007. DOI

Lozier M.J., Boyd M., Stanley C., Ogilvie L., King E., Martin C., Lewis L. Acetyl fentanyl, a novel fentanyl analog, causes 14 overdose deaths in Rhode Island, March–May 2013. J. Med. Toxicol. 2015;11:208–217. doi: 10.1007/s13181-015-0477-9. PubMed DOI PMC

Kumar K., Ballantyne J.A., Baker A.B. A sensitive assay for the simultaneous measurement of alfentanil and fentanyl in plasma. J. Pharm. Biomed. Anal. 1996;14:667–673. doi: 10.1016/0731-7085(95)01685-6. PubMed DOI

Gergov M., Nokua P., Vuori E., Qjanpera I. Simultaneous screening and quantification of 25 opioid drugs in post-mortem blood and urine by liquid chromatography-tandem mass spectrometry. Forensic Sci. Int. 2009;186:36–43. doi: 10.1016/j.forsciint.2009.01.013. PubMed DOI

Wang L.Q., Bernert J.T. Analysis of 13 fentanils, including sufentanil and carfentanil, in human urine by liquid chromatography-atmospheric-pressure ionization-tandem mass spectrometry. J. Anal. Toxicol. 2006;30:335–341. doi: 10.1093/jat/30.5.335. PubMed DOI

Kingsbury D.P., Makowski G.S., Stone J.A. Quantitative-analysis of fentanyl in pharmaceutical preparations by gas-chromatography mass-spectrometry. J. Anal. Toxicol. 1995;19:27–30. doi: 10.1093/jat/19.1.27. PubMed DOI

Slepchenko G.B., Gindullina T.M., Nekhoroshev S.V. Capabilities of the electrochemical methods in the determination of narcotic and psychotropic drugs in forensic chemistry materials. J. Anal. Chem. 2017;72:703–709. doi: 10.1134/S1061934817070127. DOI

Lin Y., Sun J.F., Tang M., Zhang G.H., Yu L., Zhao X.B., Ai R., Yu H.L., Shao B., He Y. Synergistic recognition-triggered charge transfer enables rapid visual colorimetric detection of fentanyl. Anal. Chem. 2021;93:6544–6550. doi: 10.1021/acs.analchem.1c00723. PubMed DOI

Roda G., Faggiani F., Bolchi C., Pallavicini M., Dei Cas M. Ten years of fentanyl-like drugs: A technical-analytical review. Anal. Sci. 2019;35:479–491. doi: 10.2116/analsci.18R004. PubMed DOI

Alburges M.E., Hanson G.R., Gibb J.W., Sakashita C.O., Rollins D.E. Fentanyl receptor assay 2. Utilization of a radioreceptor assay for the analysis of fentanyl analogs in urine. J. Anal. Toxicol. 1992;16:36–41. doi: 10.1093/jat/16.1.36. PubMed DOI

Peng L.J., Wen M.L., Yao Y. Potentiometric determination of fentanyl in pharmaceutical formulations. J. Pharm. Biomed. Anal. 2002;30:667–673. doi: 10.1016/S0731-7085(02)00345-X. PubMed DOI

Garrido J.M.P.J., Delerue-Matos C., Borges F., Macedo T.R.A., Oliveira-Brett A.M. Electrochemical analysis of opiates—An overview. Anal. Lett. 2004;37:831–844. doi: 10.1081/AL-120030282. DOI

Hu N.F., Hong G., Lin S.C. Adsorptive stripping voltammetry of a fentanyl derivative at a mercury-electrode. Talanta. 1994;41:1269–1274. doi: 10.1016/0039-9140(94)E0005-C. PubMed DOI

Hu N., Guo H., Lin S. Adsorptive stripping voltammetry properties of fentanyl at hg electrode. Talanta. 1994;41:1929–1932. doi: 10.1016/0039-9140(94)E0005-C. PubMed DOI

Naghian E., Khosrowshahi E.M., Sohouli E., Ahmadi F., Rahimi-Nasrabadi M., Safarifard V. A new electrochemical sensor for the detection of fentanyl lethal drug by a screen-printed carbon electrode modified with the open-ended channels of zn(ii)-mof. New J. Chem. 2020;44:9271–9277. doi: 10.1039/D0NJ01322F. DOI

Najafi M., Sohouli E., Mousavi F. An electrochemical sensor for fentanyl detection based on multi-walled carbon nanotubes as electrocatalyst and the electrooxidation mechanism. J. Anal. Chem. 2020;75:1209–1217. doi: 10.1134/S1061934820090130. DOI

Wester N., Mynttinen E., Etula J., Lilius T., Kalso E., Mikladal B.F., Zhang Q., Jiang H., Sainio S., Nordlund D., et al. Single-walled carbon nanotube network electrodes for the detection of fentanyl citrate. ACS Appl. Nano Mater. 2020;3:1203–1212. doi: 10.1021/acsanm.9b01951. DOI

Mishra R.K., Goud K.Y., Li Z.H., Moonla C., Mohamed M.A., Tehrani F., Teymourian H., Wang J. Continuous opioid monitoring along with nerve agents on a wearable microneedle sensor array. J. Am. Chem. Soc. 2020;142:5991–5995. doi: 10.1021/jacs.0c01883. PubMed DOI

Moonla C., Yugender Goud K., Teymourian H., Tangkuaram T., Ingrande J., Suresh P., Wang J. An integrated microcatheter-based dual-analyte sensor system for simultaneous, real-time measurement of propofol and fentanyl. Talanta. 2020;218:121205. doi: 10.1016/j.talanta.2020.121205. PubMed DOI

Barfidokht A., Mishra R.K., Seenivasan R., Liu S.Y., Hubble L.J., Wang J., Hall D.A. Wearable electrochemical glove-based sensor for rapid and on-site detection of fentanyl. Sensor. Actuat. B Chem. 2019;296:126422. doi: 10.1016/j.snb.2019.04.053. PubMed DOI PMC

Ott C.E., Cunha-Silva H., Kuberski S.L., Cox J.A., Arcos-Martínez M.J., Arroyo-Mora L.A. Electrochemical detection of fentanyl with screen-printed carbon electrodes using square-wave adsorptive stripping voltammetry for forensic applications. J. Electroanal. Chem. 2020;873:114425. doi: 10.1016/j.jelechem.2020.114425. DOI

Peng L.J., Wen M.L., Yao Y. Construction and performance characteristics of new fentanyl-selective plastic membrane electrode. Anal. Sci. 2001;17:815–818. doi: 10.2116/analsci.17.815. PubMed DOI

Dai H., Xu H.F., Wu X.P., Chi Y.W., Chen G.N. Fabrication of a new electrochemiluminescent sensor for fentanyl citrate based on glassy carbon microspheres and ionic liquid composite paste electrode. Anal. Chim. Acta. 2009;647:60–65. doi: 10.1016/j.aca.2009.05.032. PubMed DOI

Wang Y., Dai H., Wu X., Chen H., Xu L., Chen Y., Chen G. Electrochemiluminescence determination of fentanyl citrate with a novel glassy carbon paste electrode. Luminescence. 2008;23:99.

Ahmar H., Fakhari A.R., Tabani H., Shahsavani A. Optimization of electromembrane extraction combined with differential pulse voltammetry using modified screen-printed electrode for the determination of sufentanil. Electrochim. Acta. 2013;96:117–123. doi: 10.1016/j.electacta.2013.02.049. DOI

Milne B., Quintin L., Gillon J.Y., Pujol J.F. Fentanyl decreases catecholamine metabolism measured by in vivo voltammetry in the rat locus coeruleus. Can. J. Physiol. Pharmacol. 1989;67:532–536. doi: 10.1139/y89-085. PubMed DOI

Milne B., Quintin L., Pujol J.F. Fentanyl increases catecholamine oxidation current measured by in vivo voltammetry in the rat striatum. Can. J. Anaesth. 1989;36:155–159. doi: 10.1007/BF03011439. PubMed DOI

Goodchild S.A., Hubble L.J., Mishra R.K., Li Z.H., Goud K.Y., Barfidokht A., Shah R., Bagot K.S., McIntosh A.J.S., Wang J. Ionic liquid-modified disposable electrochemical sensor strip for analysis of fentanyl. Anal. Chem. 2019;91:3747–3753. doi: 10.1021/acs.analchem.9b00176. PubMed DOI

Kolesnichenko I.I., Balashova L.M., Korobova L.S. The development of a method of multisensory stripping voltammetry for analysis of medical preparations. Determination of fentanyl in lacrimal fluid. Biofizika. 2021;66:491–495. doi: 10.1134/S0006350921030076. DOI

Langmaier J., Maier V., Samec Z. Voltammetry of several natural and synthetic opioids at a polarized ionic liquid membrane. ChemElectroChem. 2021;8:2519–2525. doi: 10.1002/celc.202100701. DOI

Solis E., Cameron-Burr K.T., Kiyatkin E.A. Heroin contaminated with fentanyl dramatically enhances brain hypoxia and induces brain hypothermia. Eneuro. 2017;4 doi: 10.1523/ENEURO.0323-17.2017. PubMed DOI PMC

Solis E., Cameron-Burr K.T., Shaham Y., Kiyatkin E.A. Fentanyl-induced brain hypoxia triggers brain hyperglycemia and biphasic changes in brain temperature. Neuropsychopharmacology. 2018;43:810–819. doi: 10.1038/npp.2017.181. PubMed DOI PMC

Kiyatkin E.A. Central and peripheral mechanisms underlying physiological and drug-induced fluctuations in brain oxygen in freely-moving rats. Front. Integrat. Neurosci. 2018;12:44. doi: 10.3389/fnint.2018.00044. PubMed DOI PMC

Misailidi N., Papoutsis I., Nikolaou P., Katselou M., Spiliopoulou C., Athanaselis S. Furanylfentanyl: Another fentanyl analogue, another hazard for public health. Forensic Toxicol. 2018;36:1–11. doi: 10.1007/s11419-017-0371-z. DOI

Evaluation of Fentanyl Exposure Effects on Butyrylcholinesterase Activity as a Tool for Future On-Site Detection Methods

Fentanyl and its derivatives: Pain-killers or man-killers?