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Maitland AD, McGriff SA, Glatfelter GC, Schindler CW, Baumann MH. Reinforcing effects of fentanyl analogs found in illicit drug markets. Psychopharmacology (Berl) 2024:10.1007/s00213-024-06641-6. [PMID: 38965085 DOI: 10.1007/s00213-024-06641-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Accepted: 06/20/2024] [Indexed: 07/06/2024]
Abstract
RATIONALE The potent synthetic opioid fentanyl, and its analogs, continue to drive opioid-related overdoses. Although the pharmacology of fentanyl is well characterized, there is little information about the reinforcing effects of clandestine fentanyl analogs (FAs). OBJECTIVES Here, we compared the effects of fentanyl and the FAs acetylfentanyl, butyrylfentanyl, and cyclopropylfentanyl on drug self-administration in male and female rats. These FAs feature chemical modifications at the carbonyl moiety of the fentanyl scaffold. METHODS Sprague-Dawley rats fitted with intravenous jugular catheters were placed in chambers containing two nose poke holes. Active nose poke responses resulted in drug delivery (0.2 mL) over 2 s on a fixed-ratio 1 schedule, followed by a 20 s timeout. Acquisition doses were 0.01 mg/kg/inj for fentanyl and cyclopropylfentanyl, and 0.03 mg/kg/inj for acetylfentanyl and butyrylfentanyl. After 10 days of acquisition, dose-effect testing was carried out, followed by 10 days of saline extinction. RESULTS Self-administration of fentanyl and FAs was acquired by both male and female rats, with no sex differences in acquisition rate. Fentanyl and FAs showed partial inverted-U dose-effect functions; cyclopropylfentanyl and fentanyl had similar potency, while acetylfentanyl and butyrylfentanyl were less potent. Maximal response rates were similar across drugs, with fentanyl and cyclopropylfentanyl showing maximum responding at 0.001 mg/kg/inj, acetylfentanyl at 0.01 mg/kg/inj, and butyrylfentanyl at 0.003 mg/kg/inj. No sex differences were detected for drug potency, efficacy, or rates of extinction. CONCLUSIONS Our work provides new evidence that FAs display significant abuse liability in male and female rats, which suggests the potential for compulsive use in humans.
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Affiliation(s)
- Alexander D Maitland
- Designer Drug Research Unit (DDRU), National Institute on Drug Abuse (NIDA), Intramural Research Program (IRP), 333 Cassell Drive, Suite 4400, Baltimore, MD, 21224, USA
| | - Shelby A McGriff
- Designer Drug Research Unit (DDRU), National Institute on Drug Abuse (NIDA), Intramural Research Program (IRP), 333 Cassell Drive, Suite 4400, Baltimore, MD, 21224, USA
| | - Grant C Glatfelter
- Designer Drug Research Unit (DDRU), National Institute on Drug Abuse (NIDA), Intramural Research Program (IRP), 333 Cassell Drive, Suite 4400, Baltimore, MD, 21224, USA
| | - Charles W Schindler
- Designer Drug Research Unit (DDRU), National Institute on Drug Abuse (NIDA), Intramural Research Program (IRP), 333 Cassell Drive, Suite 4400, Baltimore, MD, 21224, USA
| | - Michael H Baumann
- Designer Drug Research Unit (DDRU), National Institute on Drug Abuse (NIDA), Intramural Research Program (IRP), 333 Cassell Drive, Suite 4400, Baltimore, MD, 21224, USA.
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Landge VG, Mishra A, Thotamune W, Bonds AL, Alahakoon I, Karunarathne A, Young MC. Selective C-H Activation of Unprotected Allylamines by Control of Catalyst Speciation. CHEM CATALYSIS 2023; 3:100809. [PMID: 37982045 PMCID: PMC10653252 DOI: 10.1016/j.checat.2023.100809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2023]
Abstract
An outstanding challenge in the Pd-catalyzed functionalization of allylamines is the control of stereochemistry. Terminal alkenes preferentially undergo Heck-type reactions, while internal alkenes may undergo a mixture of Heck and C-H activation reactions that give mixtures of stereochemical products. In the case of unprotected allylamines, the challenge in achieving C-H activation is that facile in situ formation of Pd nanoparticles leads to preferential formation of trans rather than cis-substituted products. In this study we have demonstrated the feasibility of using mono-protected amino acid (MPAA) ligands as metal protecting groups to prevent aggregation and reduction, allowing the selective synthesis of free cis-arylated allylamines. This method complements Heck-selective methods, allowing complete stereochemical control over the synthesis of cinnamylamines, an important class of amine that can serve as therapeutics directly or as advanced intermediates. To highlight the utility of the methodology, we have demonstrated rapid access to mu opioid receptor ligands.
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Affiliation(s)
- Vinod G. Landge
- Department of Chemistry & Biochemistry, School of Green Chemistry & Engineering, The University of Toledo, Toledo, OH 43606, USA
| | - Ankita Mishra
- Department of Chemistry & Biochemistry, School of Green Chemistry & Engineering, The University of Toledo, Toledo, OH 43606, USA
| | - Waruna Thotamune
- Department of Chemistry, Saint Louis University, 3501 Laclede Avenue, St. Louis, MO 63103, USA
| | - Audrey L. Bonds
- Department of Chemistry & Biochemistry, School of Green Chemistry & Engineering, The University of Toledo, Toledo, OH 43606, USA
| | - Indunil Alahakoon
- Department of Chemistry & Biochemistry, School of Green Chemistry & Engineering, The University of Toledo, Toledo, OH 43606, USA
| | - Ajith Karunarathne
- Department of Chemistry, Saint Louis University, 3501 Laclede Avenue, St. Louis, MO 63103, USA
| | - Michael C. Young
- Department of Chemistry & Biochemistry, School of Green Chemistry & Engineering, The University of Toledo, Toledo, OH 43606, USA
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Xie B, Le Rouzic VP, Goldberg A, Tsai MHM, Chen L, Zhang T, Sinha A, Pan YX, Baumann MH, Shi L. Binding preference at the μ-opioid receptor underlies distinct pharmacology of cyclopropyl versus valeryl analogs of fentanyl. Neuropharmacology 2023; 227:109442. [PMID: 36731721 PMCID: PMC9974845 DOI: 10.1016/j.neuropharm.2023.109442] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 01/12/2023] [Accepted: 01/25/2023] [Indexed: 01/31/2023]
Abstract
Illicitly manufactured fentanyl is driving the current opioid crisis, and various fentanyl analogs are appearing in recreational drug markets worldwide. To assess the potential health risks posed by fentanyl analogs, it is necessary to understand structure-activity relationships for these compounds. Here we compared the pharmacology of two structurally related fentanyl analogs implicated in opioid overdose: cyclopropylfentanyl and valerylfentanyl. Cyclopropylfentanyl has a three-carbon ring attached to the carbonyl group on the fentanyl scaffold, whereas valerylfentanyl has a four-carbon chain at the same position. In vitro assays examining μ-opioid receptor (MOR) coupling to G proteins in CHO cells showed that cyclopropylfentanyl is a full agonist (EC50 = 8.6 nM, %Emax = 113%), with potency and efficacy similar to fentanyl (EC50 = 10.3 nM, %Emax = 113%). By contrast, valerylfentanyl is a partial agonist at MOR (EC50 = 179.8 nM, %Emax = 60%). Similar results were found in assays assessing MOR-mediated β-arrestin recruitment in HEK cells. In vivo studies in male CD-1 mice demonstrated that both fentanyl analogs induce naloxone-reversible antinociception and respiratory suppression, but cyclopropylfentanyl is 100-times more potent as an antinociceptive agent (ED50 = 0.04 mg/kg, s. c.) than valerylfentanyl (ED50 = 4.0 mg/kg, s. c.). Molecular simulation results revealed that the alkyl chain of valerylfentanyl cannot be well accommodated by the active state of MOR and may transition the receptor toward an inactive state, converting the fentanyl scaffold to a partial agonist. Taken together, our results suggest that cyclopropylfentanyl presents much greater risk of adverse effects when compared to valerylfentanyl. Moreover, the summed findings may provide clues to the design of therapeutic opioids with reduced adverse side effects.
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Affiliation(s)
- Bing Xie
- Computational Chemistry and Molecular Biophysics Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Valerie P Le Rouzic
- Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
| | - Alexander Goldberg
- Computational Chemistry and Molecular Biophysics Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Meng-Hua M Tsai
- Computational Chemistry and Molecular Biophysics Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Li Chen
- Computational Chemistry and Molecular Biophysics Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Tiffany Zhang
- Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
| | - Antara Sinha
- Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
| | - Ying-Xian Pan
- Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA; Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ, 07103, USA
| | - Michael H Baumann
- Designer Drug Research Unit, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Lei Shi
- Computational Chemistry and Molecular Biophysics Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA.
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Varshneya NB, Hassanien SH, Holt MC, Stevens DL, Layle NK, Bassman JR, Iula DM, Beardsley PM. Respiratory depressant effects of fentanyl analogs are opioid receptor-mediated. Biochem Pharmacol 2021; 195:114805. [PMID: 34673011 DOI: 10.1016/j.bcp.2021.114805] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/09/2021] [Accepted: 10/13/2021] [Indexed: 02/04/2023]
Abstract
Opioid-related fatalities involving synthetic opioids have reached unprecedented levels. This study evaluated the respiratory depressant effects of seven fentanyl analogs that have either emerged in the illicit drug supply or been identified in toxicological analyses following fatal or non-fatal intoxications. Adult male Swiss Webster mice were administered fentanyl analogs (isobutyrylfentanyl, crotonylfentanyl, para-methoxyfentanyl, para-methoxybutyrylfentanyl, 3-furanylfentanyl, thiophenefentanyl, and benzodioxolefentanyl) and their effects on minute volume as compared to mu-opioid receptor (MOR) agonist standards (fentanyl, morphine, and buprenorphine) were measured using whole body plethysmography (WBP). All drugs elicited significant (p ≤ 0.05) hypoventilation relative to vehicle for at least one dose tested: morphine (1, 3.2, 10, 32 mg/kg), buprenorphine, (0.032, 0.1, 0.32, 1, 3.2 mg/kg), fentanyl (0.0032, 0.01, 0.032, 0.1, 1, 32 mg/kg), isobutyrylfentanyl (0.1, 0.32, 1, 3.2, 10 mg/kg), crotonylfentanyl (0.1, 0.32, 1, 3.2, 10 mg/kg), para-methoxyfentanyl (0.1, 0.32, 1, 3.2, 10 mg/kg), para-methoxybutyrylfentanyl (0.32, 1, 3.2, 10 mg/kg), 3-furanylfentanyl (0.1, 0.32, 1, 3.2, 10 mg/kg), thiophenefentanyl (1, 3.2, 10, 32, 100 mg/kg), and benzodioxolefentanyl (3.2, 10, 32, 100 mg/kg). The ED50 values for hypoventilation showed a rank order of potency as follows: fentanyl (ED50 = 0.96 mg/kg) > 3-furanylfentanyl (ED50 = 2.60 mg/kg) > crotonylfentanyl (ED50 = 2.72 mg/kg) > para-methoxyfentanyl (ED50 = 3.31 mg/kg) > buprenorphine (ED50 = 10.8 mg/kg) > isobutyrylfentanyl (ED50 = 13.5 mg/kg) > para-methoxybutyrylfentanyl (ED50 = 16.1 mg/kg) > thiophenefentanyl (ED50 = 18.0 mg/kg) > morphine (ED50 = 55.3 mg/kg) > benzodioxolefentanyl (ED50 = 10,168 mg/kg). A naloxone pretreatment (10 mg/kg) attenuated the hypoventilatory effects of all drugs. These results establish that the respiratory depressant effects of these fentanyl analogs are at least in part mediated by the MOR.
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Affiliation(s)
- Neil B Varshneya
- Behavioral Pharmacology Research Unit, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
| | - Sherif H Hassanien
- Forensic Chemistry Division, Cayman Chemical Company, Ann Arbor, MI, USA
| | - Melissa C Holt
- Forensic Chemistry Division, Cayman Chemical Company, Ann Arbor, MI, USA
| | - David L Stevens
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Nathan K Layle
- Forensic Chemistry Division, Cayman Chemical Company, Ann Arbor, MI, USA
| | - Jonathon R Bassman
- Forensic Chemistry Division, Cayman Chemical Company, Ann Arbor, MI, USA
| | - Donna M Iula
- Forensic Chemistry Division, Cayman Chemical Company, Ann Arbor, MI, USA
| | - Patrick M Beardsley
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA; Center for Biomarker Research & Precision Medicine, Virginia Commonwealth University School of Pharmacy, Richmond, VA, USA
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Pharmacokinetics and pharmacodynamics of cyclopropylfentanyl in male rats. Psychopharmacology (Berl) 2021; 238:3629-3641. [PMID: 34613431 PMCID: PMC8629808 DOI: 10.1007/s00213-021-05981-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 09/06/2021] [Indexed: 01/29/2023]
Abstract
BACKGROUND Illicitly manufactured fentanyl and its analogs are a major driving force behind the ongoing opioid crisis. Cyclopropylfentanyl is a fentanyl analog associated with many overdose deaths, but limited knowledge is available about its pharmacology. In the present study, we developed a bioanalytical method for the determination of cyclopropylfentanyl and its main metabolite cyclopropylnorfentanyl and evaluated pharmacokinetic-pharmacodynamic relationships in rats. METHOD An ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for determination of cyclopropylfentanyl and cyclopropylnorfentanyl in rat plasma. Male Sprague-Dawley rats fitted with jugular catheters and temperature transponders received cyclopropylfentanyl (30, 100, and 300 μg/kg) or saline subcutaneously. Blood specimens were withdrawn over an 8-h time period, along with measurements of pharmacodynamic endpoints. RESULTS The analytical method was validated, and both analytes exhibited a low limit of quantification (15 pg/mL). Cyclopropylfentanyl caused dose-related increases in hot plate latency (ED50 = 48 µg/kg) and catalepsy (ED50 = 87 µg/kg) and produced long-lasting hypothermia at the highest dose. Plasma cyclopropylfentanyl rose rapidly in a dose-related fashion, reaching maximal concentration (Cmax) after 15-28 min, whereas metabolite Cmax occurred later at 45-90 min. Cyclopropylfentanyl Cmax values were similar to concentrations measured in non-fatal intoxications in humans; however, differences in parent drug: metabolite ratio indicated possible interspecies variance in metabolism. CONCLUSION Our study shows that cyclopropylfentanyl produces typical opioid-like effects in male rats. Cyclopropylfentanyl displays much greater analgesic potency when compared to morphine, suggesting that cyclopropylfentanyl poses increased overdose risk for unsuspecting users.
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Åstrand A, Vikingsson S, Jakobsen I, Björn N, Kronstrand R, Gréen H. Activation of the μ-opioid receptor by alicyclic fentanyls: Changes from high potency full agonists to low potency partial agonists with increasing alicyclic substructure. Drug Test Anal 2020; 13:169-174. [PMID: 32749741 PMCID: PMC7891621 DOI: 10.1002/dta.2906] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 07/14/2020] [Accepted: 07/31/2020] [Indexed: 12/12/2022]
Abstract
Fentanyl analogs represent an important group of new psychoactive substances and knowing their efficacy and potency might assist in interpreting observed concentrations. The potency of fentanyl analogs can be estimated from in vitro studies and can be used to establish structure–activity relationships. In this study, recombinant CHO‐K1 cells (AequoScreen) expressing the human μ‐opioid receptor were used to establish dose–response curves via luminescent analysis for cyclopropyl‐, cyclobutyl‐, cyclopentyl‐, cyclohexyl‐, and 2,2,3,3‐tetramethylcyclopropylfentanyl (TMCPF), on three separate occasions, using eight different concentrations in an eight‐fold serial dilution in triplicates starting at ~60 μM. Fentanyl was used as a full agonist reference while morphine and buprenorphine were included for comparison. Cyclopropylfentanyl (EC50 = 4.3 nM), cyclobutylfentanyl (EC50 = 6.2 nM), and cyclopentylfentanyl (EC50 = 13 nM) were full agonists slightly less potent than fentanyl (EC50 = 1.7 nM). Cyclohexylfentanyl (EC50 = 3.1 μM, efficacy 48%) and TMCPF (EC50 = 1.5 μM, efficacy 65%) were partial agonists less potent than morphine (EC50 = 430 nM). Based on the results, cyclopropyl‐, cyclobutyl‐, and cyclopentylfentanyl would be expected to induce intoxication or cause fatal poisonings at similar concentrations to fentanyl, while the toxic or fatal concentrations of cyclohexylfentanyl and TMCPF would be expected to be much higher.
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Affiliation(s)
- Anna Åstrand
- Division of Drug Research, Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Svante Vikingsson
- Division of Drug Research, Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden.,Department of Forensic Genetics and Forensic Toxicology, National Board of Forensic Medicine, Linköping, Sweden
| | - Ingrid Jakobsen
- Division of Drug Research, Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden.,Department of Laboratory Medicine, Örebro University Hospital, Örebro, Sweden
| | - Niclas Björn
- Division of Drug Research, Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Robert Kronstrand
- Division of Drug Research, Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden.,Department of Forensic Genetics and Forensic Toxicology, National Board of Forensic Medicine, Linköping, Sweden
| | - Henrik Gréen
- Division of Drug Research, Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden.,Department of Forensic Genetics and Forensic Toxicology, National Board of Forensic Medicine, Linköping, Sweden
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