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Lu HR, Damiano BP, Kreir M, Rohrbacher J, van der Linde H, Saidov T, Teisman A, Gallacher DJ. The Potential Mechanisms behind Loperamide-Induced Cardiac Arrhythmias Associated with Human Abuse and Extreme Overdose. Biomolecules 2023; 13:1355. [PMID: 37759755 PMCID: PMC10527387 DOI: 10.3390/biom13091355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 09/01/2023] [Accepted: 09/03/2023] [Indexed: 09/29/2023] Open
Abstract
Loperamide has been a safe and effective treatment for diarrhea for many years. However, many cases of cardiotoxicity with intentional abuse of loperamide ingestion have recently been reported. We evaluated loperamide in in vitro and in vivo cardiac safety models to understand the mechanisms for this cardiotoxicity. Loperamide slowed conduction (QRS-duration) starting at 0.3 µM [~1200-fold (×) its human Free Therapeutic Plasma Concentration; FTPC] and reduced the QT-interval and caused cardiac arrhythmias starting at 3 µM (~12,000× FTPC) in an isolated rabbit ventricular-wedge model. Loperamide also slowed conduction and elicited Type II/III A-V block in anesthetized guinea pigs at overdose exposures of 879× and 3802× FTPC. In ion-channel studies, loperamide inhibited hERG (IKr), INa, and ICa currents with IC50 values of 0.390 µM, 0.526 µM, and 4.091 µM, respectively (i.e., >1560× FTPC). Additionally, in silico trials in human ventricular action potential models based on these IC50s confirmed that loperamide has large safety margins at therapeutic exposures (≤600× FTPC) and confirmed repolarization abnormalities in the case of extreme doses of loperamide. The studies confirmed the large safety margin for the therapeutic use of loperamide but revealed that at the extreme exposure levels observed in human overdose, loperamide can cause a combination of conduction slowing and alterations in repolarization time, resulting in cardiac proarrhythmia. Loperamide's inhibition of the INa channel and hERG-mediated IKr are the most likely basis for this cardiac electrophysiological toxicity at overdose exposures. The cardiac toxic effects of loperamide at the overdoses could be aggravated by co-medication with other drug(s) causing ion channel inhibition.
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Affiliation(s)
- Hua Rong Lu
- Global Safety Pharmacology, Janssen Research and Development, Turnhoutseweg 30, 2340 Beerse, Belgium; (B.P.D.); (J.R.); (H.v.d.L.); (T.S.); (A.T.); (D.J.G.)
| | | | - Mohamed Kreir
- Global Safety Pharmacology, Janssen Research and Development, Turnhoutseweg 30, 2340 Beerse, Belgium; (B.P.D.); (J.R.); (H.v.d.L.); (T.S.); (A.T.); (D.J.G.)
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Van Ammel K, Urmaliya V, Lu HR, Rohrbacher J, Kopljar I, Jansen H, Gallacher DJ, Teisman A. A translational analysis: In vitro hiPSC cardiomyocytes to human phase I analysis for a set of reference compounds with different QT/TdP risk categories. J Pharmacol Toxicol Methods 2019. [DOI: 10.1016/j.vascn.2019.05.127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Rohrbacher J, Jansen H, Van Ammel K, Lu HR, Urmaliya V, Teisman A, Gallacher DJ. A translational analysis: Cardiac ion channels and isolated rabbit left ventricular wedge in predicting CV safety risk. J Pharmacol Toxicol Methods 2019. [DOI: 10.1016/j.vascn.2019.05.128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Jansen H, Urmaliya V, Van Ammel K, van der Linde H, Rohrbacher J, Teisman A, Gallacher DJ. Translational research: What can we learn from the predictability of anesthetized guinea-pig and dog models for cardiovascular safety findings in man? J Pharmacol Toxicol Methods 2019. [DOI: 10.1016/j.vascn.2019.05.129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Urmaliya V, Van Ammel K, Rohrbacher J, van der Linde H, Lu HR, Jansen H, Gallacher DJ, Teisman A. An integrated translational analysis summary: Prediction of HERG, isolated wedge preparation, anaesthetized guinea pig and dog towards phase I clinical data for drugs with different QT/TdP risk categories. J Pharmacol Toxicol Methods 2019. [DOI: 10.1016/j.vascn.2019.05.130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Rohrbacher J, Loenders B, Hermans AN, Gallacher DJ. Evaluation of a hERG Receptor Binding and a Functional Patch Clamp Assay: How Do These Translate? J Pharmacol Toxicol Methods 2017. [DOI: 10.1016/j.vascn.2017.09.151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Passini E, Britton OJ, Lu HR, Rohrbacher J, Hermans AN, Gallacher DJ, Greig RJH, Bueno-Orovio A, Rodriguez B. Human In Silico Drug Trials Demonstrate Higher Accuracy than Animal Models in Predicting Clinical Pro-Arrhythmic Cardiotoxicity. Front Physiol 2017; 8:668. [PMID: 28955244 PMCID: PMC5601077 DOI: 10.3389/fphys.2017.00668] [Citation(s) in RCA: 162] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 08/23/2017] [Indexed: 01/08/2023] Open
Abstract
Early prediction of cardiotoxicity is critical for drug development. Current animal models raise ethical and translational questions, and have limited accuracy in clinical risk prediction. Human-based computer models constitute a fast, cheap and potentially effective alternative to experimental assays, also facilitating translation to human. Key challenges include consideration of inter-cellular variability in drug responses and integration of computational and experimental methods in safety pharmacology. Our aim is to evaluate the ability of in silico drug trials in populations of human action potential (AP) models to predict clinical risk of drug-induced arrhythmias based on ion channel information, and to compare simulation results against experimental assays commonly used for drug testing. A control population of 1,213 human ventricular AP models in agreement with experimental recordings was constructed. In silico drug trials were performed for 62 reference compounds at multiple concentrations, using pore-block drug models (IC50/Hill coefficient). Drug-induced changes in AP biomarkers were quantified, together with occurrence of repolarization/depolarization abnormalities. Simulation results were used to predict clinical risk based on reports of Torsade de Pointes arrhythmias, and further evaluated in a subset of compounds through comparison with electrocardiograms from rabbit wedge preparations and Ca2+-transient recordings in human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs). Drug-induced changes in silico vary in magnitude depending on the specific ionic profile of each model in the population, thus allowing to identify cell sub-populations at higher risk of developing abnormal AP phenotypes. Models with low repolarization reserve (increased Ca2+/late Na+ currents and Na+/Ca2+-exchanger, reduced Na+/K+-pump) are highly vulnerable to drug-induced repolarization abnormalities, while those with reduced inward current density (fast/late Na+ and Ca2+ currents) exhibit high susceptibility to depolarization abnormalities. Repolarization abnormalities in silico predict clinical risk for all compounds with 89% accuracy. Drug-induced changes in biomarkers are in overall agreement across different assays: in silico AP duration changes reflect the ones observed in rabbit QT interval and hiPS-CMs Ca2+-transient, and simulated upstroke velocity captures variations in rabbit QRS complex. Our results demonstrate that human in silico drug trials constitute a powerful methodology for prediction of clinical pro-arrhythmic cardiotoxicity, ready for integration in the existing drug safety assessment pipelines.
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Affiliation(s)
- Elisa Passini
- Computational Cardiovascular Science Group, Department of Computer Science, University of OxfordOxford, United Kingdom
| | - Oliver J Britton
- Computational Cardiovascular Science Group, Department of Computer Science, University of OxfordOxford, United Kingdom
| | - Hua Rong Lu
- Global Safety, Pharmacology, Discovery Sciences, Janssen Research and Development, Janssen Pharmaceutica NVBeerse, Belgium
| | - Jutta Rohrbacher
- Global Safety, Pharmacology, Discovery Sciences, Janssen Research and Development, Janssen Pharmaceutica NVBeerse, Belgium
| | - An N Hermans
- Global Safety, Pharmacology, Discovery Sciences, Janssen Research and Development, Janssen Pharmaceutica NVBeerse, Belgium
| | - David J Gallacher
- Global Safety, Pharmacology, Discovery Sciences, Janssen Research and Development, Janssen Pharmaceutica NVBeerse, Belgium
| | | | - Alfonso Bueno-Orovio
- Computational Cardiovascular Science Group, Department of Computer Science, University of OxfordOxford, United Kingdom
| | - Blanca Rodriguez
- Computational Cardiovascular Science Group, Department of Computer Science, University of OxfordOxford, United Kingdom
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Kuijlaars J, Oyelami T, Diels A, Rohrbacher J, Versweyveld S, Meneghello G, Tuefferd M, Verstraelen P, Detrez JR, Verschuuren M, De Vos WH, Meert T, Peeters PJ, Cik M, Nuydens R, Brône B, Verheyen A. Sustained synchronized neuronal network activity in a human astrocyte co-culture system. Sci Rep 2016; 6:36529. [PMID: 27819315 PMCID: PMC5098163 DOI: 10.1038/srep36529] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 10/17/2016] [Indexed: 02/03/2023] Open
Abstract
Impaired neuronal network function is a hallmark of neurodevelopmental and neurodegenerative disorders such as autism, schizophrenia, and Alzheimer's disease and is typically studied using genetically modified cellular and animal models. Weak predictive capacity and poor translational value of these models urge for better human derived in vitro models. The implementation of human induced pluripotent stem cells (hiPSCs) allows studying pathologies in differentiated disease-relevant and patient-derived neuronal cells. However, the differentiation process and growth conditions of hiPSC-derived neurons are non-trivial. In order to study neuronal network formation and (mal)function in a fully humanized system, we have established an in vitro co-culture model of hiPSC-derived cortical neurons and human primary astrocytes that recapitulates neuronal network synchronization and connectivity within three to four weeks after final plating. Live cell calcium imaging, electrophysiology and high content image analyses revealed an increased maturation of network functionality and synchronicity over time for co-cultures compared to neuronal monocultures. The cells express GABAergic and glutamatergic markers and respond to inhibitors of both neurotransmitter pathways in a functional assay. The combination of this co-culture model with quantitative imaging of network morphofunction is amenable to high throughput screening for lead discovery and drug optimization for neurological diseases.
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Affiliation(s)
- Jacobine Kuijlaars
- Hasselt University, Biomedical Research Institute, Diepenbeek, B-3590, Belgium
| | - Tutu Oyelami
- Janssen Research & Development, a division of Janssen Pharmaceutica N.V, Beerse, B-2340, Belgium
| | - Annick Diels
- Janssen Research & Development, a division of Janssen Pharmaceutica N.V, Beerse, B-2340, Belgium
| | - Jutta Rohrbacher
- Janssen Research & Development, a division of Janssen Pharmaceutica N.V, Beerse, B-2340, Belgium
| | - Sofie Versweyveld
- Janssen Research & Development, a division of Janssen Pharmaceutica N.V, Beerse, B-2340, Belgium
| | - Giulia Meneghello
- Janssen Research & Development, a division of Janssen Pharmaceutica N.V, Beerse, B-2340, Belgium
| | - Marianne Tuefferd
- Janssen Research & Development, a division of Janssen Pharmaceutica N.V, Beerse, B-2340, Belgium
| | - Peter Verstraelen
- Antwerp University, Department of Veterinary Science, Antwerp, B-2020, Belgium
| | - Jan R. Detrez
- Antwerp University, Department of Veterinary Science, Antwerp, B-2020, Belgium
| | - Marlies Verschuuren
- Antwerp University, Department of Veterinary Science, Antwerp, B-2020, Belgium
| | - Winnok H. De Vos
- Antwerp University, Department of Veterinary Science, Antwerp, B-2020, Belgium
- Ghent University, Department of Molecular Biotechnology, Ghent, B-9000, Belgium
| | - Theo Meert
- Hasselt University, Biomedical Research Institute, Diepenbeek, B-3590, Belgium
- Janssen Research & Development, a division of Janssen Pharmaceutica N.V, Beerse, B-2340, Belgium
| | - Pieter J. Peeters
- Janssen Research & Development, a division of Janssen Pharmaceutica N.V, Beerse, B-2340, Belgium
| | - Miroslav Cik
- Janssen Research & Development, a division of Janssen Pharmaceutica N.V, Beerse, B-2340, Belgium
| | - Rony Nuydens
- Janssen Research & Development, a division of Janssen Pharmaceutica N.V, Beerse, B-2340, Belgium
| | - Bert Brône
- Hasselt University, Biomedical Research Institute, Diepenbeek, B-3590, Belgium
| | - An Verheyen
- Janssen Research & Development, a division of Janssen Pharmaceutica N.V, Beerse, B-2340, Belgium
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Lu HR, Hermans A, Kopljar I, Rohrbacher J, Teisman A, Gallacher DJ. Could in vitro animal assays be replaced by human stem cell-based assays for drug-induced cardiac risks: Beyond QT-prolongation/CIPA? J Pharmacol Toxicol Methods 2016. [DOI: 10.1016/j.vascn.2016.02.164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Pugsley M, Rohrbacher J, Gallacher D, Waldie I, Gillard N. The hERG channel blocking actions of astemizole and dofetilide in CHO vs. HEK cells. J Pharmacol Toxicol Methods 2015. [DOI: 10.1016/j.vascn.2015.08.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Rohrbacher J, Damiano BP, Girgis IG, Pugsley MK, Teisman A, Gallacher DJ. The source of hERG IC50 values (manual vs. automated patch clamp) may influence in silico modeling. J Pharmacol Toxicol Methods 2015. [DOI: 10.1016/j.vascn.2015.08.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Damiano BP, Rohrbacher J, Pugsley MK, Girgis I, Lu HR, Gallacher DJ. A comparison of in silico cardiac action potential simulations with electrophysiological effects in the isolated rabbit wedge preparation for compounds with different ion channel blocking profiles. J Pharmacol Toxicol Methods 2015. [DOI: 10.1016/j.vascn.2015.08.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Lu HR, Rohrbacher J, Hermans AN, Gallacher DJ. Lack of clear effects of QT-shortening drugs in human pluripotent stem cell-derived cardiomyocytes: A mystery that still needs to be solved. J Pharmacol Toxicol Methods 2014. [DOI: 10.1016/j.vascn.2014.03.156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Braam S, Langenberg K, Rohrbacher J, Grandela K, Mummery C, Towart R, Cik M, Diels A, Lu HR, Gallacher D. Cellular assays for monitoring cardiomyocyte electrophysiology. J Pharmacol Toxicol Methods 2013. [DOI: 10.1016/j.vascn.2013.01.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Eichenbaum G, Pugsley MK, Gallacher DJ, Towart R, McIntyre G, Shukla U, Davenport JM, Lu HR, Rohrbacher J, Hillsamer V. Role of mixed ion channel effects in the cardiovascular safety assessment of the novel anti-MRSA fluoroquinolone JNJ-Q2. Br J Pharmacol 2012; 166:1694-707. [PMID: 22289150 DOI: 10.1111/j.1476-5381.2012.01874.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE JNJ-Q2, a novel broad-spectrum fluoroquinolone with anti-methicillin-resistant Staphylococcus aureus activity, was evaluated in a comprehensive set of non-clinical and clinical cardiovascular safety studies. The effect of JNJ-Q2 on different cardiovascular parameters was compared with that of moxifloxacin, sparfloxacin and ofloxacin. Through comparisons with these well-known fluoroquinolones, the importance of effects on compensatory ion channels to the cardiovascular safety of JNJ-Q2 was investigated. EXPERIMENTAL APPROACH JNJ-Q2 and comparator fluoroquinolones were evaluated in the following models/test systems: hERG-transfected HEK293 cells sodium channel-transfected CHO cells, guinea pig right atria, arterially perfused rabbit left ventricular wedge preparations and in vivo studies in anaesthetized guinea pigs, anaesthetized and conscious telemetered dogs, and a thorough QT study in humans. KEY RESULTS The trend for effects of JNJ-Q2 on Tp-Te, QT, QRS and PR intervals in the non-clinical models and the plateau in QTc with increasing plasma concentration in humans are consistent with offsetting sodium and calcium channel activities that were observed in the non-clinical studies. These mixed ion channel activities result in the less pronounced or comparable increase in QTc interval for JNJ-Q2 compared with moxifloxacin and sparfloxacin despite its greater in vitro inhibition of I(Kr). CONCLUSIONS AND IMPLICATIONS Based on the non-clinical and clinical cardiovascular safety assessment, JNJ-Q2 has a safe cardiovascular profile for administration in humans with comparable or reduced potential to prolong QT intervals, compared with moxifloxacin. The results demonstrate the importance of compensatory sodium and calcium channel activity in offsetting potassium channel activity for compounds with a fluoroquinolone core.
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Affiliation(s)
- G Eichenbaum
- Janssen Research & Development, LLC., a division of Janssen Pharmaceutical Companies of Johnson & Johnson, Drug Safety Sciences, Raritan, NJ 08869, USA.
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Lu HR, Vlaminckx E, Rohrbacher J, Cools F, Gallacher GJ. Direct effects of arsenic trioxide on action potentials in isolated cardiac tissues: Importance of the choice of species, type of cardiac tissues and perfusion time. J Pharmacol Toxicol Methods 2012. [DOI: 10.1016/j.vascn.2012.08.076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Cools FJ, Janssens S, Vanlommel A, Verrelst J, de Hoogt R, Rohrbacher J, Lu HR, Teisman A, Gallacher DJ. Can hERG trafficking be detected in vivo? Effects of sub-acute dosing of arsenic trioxide in telemetered guinea-pigs. J Pharmacol Toxicol Methods 2012. [DOI: 10.1016/j.vascn.2012.08.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Loenders BG, Verrelst J, Lu HR, Vlaminckx E, Rohrbacher J, Teisman A, Gallacher DJ. Compound-X-induced TdP in the anesthetized guinea-pig: Unraveling the mechanism of action. J Pharmacol Toxicol Methods 2010. [DOI: 10.1016/j.vascn.2010.11.078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Lu HR, Rohrbacher J, Vlaminckx E, Van Ammel K, Yan GX, Gallacher DJ. Predicting drug-induced slowing of conduction and pro-arrhythmia: identifying the 'bad' sodium current blockers. Br J Pharmacol 2010; 160:60-76. [PMID: 20331615 DOI: 10.1111/j.1476-5381.2010.00646.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE The regulatory guidelines (ICHS7B) for the identification of only drug-induced long QT and pro-arrhythmias have certain limitations. EXPERIMENTAL APPROACH Conduction time (CT) was measured in isolated Purkinje fibres, left ventricular perfused wedges and perfused hearts from rabbits, and sodium current was measured in Chinese hamster ovary cells, transfected with Na(v)1.5 channels. KEY RESULTS A total of 355 compounds were screened for their effects on CT: 32% of these compounds slowed conduction, 65% had no effect and 3% accelerated conduction. Lidocaine and flecainide, which slow conduction, were tested in more detail as reference compounds. In isolated Purkinje fibres, flecainide largely slowed conduction and markedly increased triangulation, while lidocaine slightly slowed conduction and did not produce significant triangulation. Also in isolated left ventricular wedge preparations, flecainide largely slowed conduction in a rate-dependent manner, and elicited ventricular tachycardia (VT). Lidocaine slightly slowed conduction, reduced Tp-Te and did not induce VT. Similarly in isolated hearts, flecainide markedly slowed conduction, increased Tp-Te and elicited VT or ventricular fibrillation (VF). The slowing of conduction and induction of VT/VF with flecainide was much more evident in a condition of ischaemia/reperfusion. Lidocaine abolished ischaemia/reperfusion-induced VT/VF. Flecainide blocked sodium current (I(Na)) preferentially in the activated state (i.e. open channel) with slow binding and dissociation rates in a use-dependent manner, and lidocaine weakly blocked I(Na). CONCLUSION AND IMPLICATIONS Slowing conduction by blocking I(Na) could be potentially pro-arrhythmic. It is possible to differentiate between compounds with 'good' (lidocaine-like) and 'bad' (flecainide-like) I(Na) blocking activities in these models.
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Affiliation(s)
- Hua Rong Lu
- Center of Excellence for Cardiovascular Safety Research, Johnson & Johnson Pharmaceutical Research & Development (PRD), Division of Janssen Pharmaceutica, Beerse, Belgium.
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Lu HR, Vlaminckx E, Van de Water A, Rohrbacher J, Hermans A, Gallacher DJ. In-vitro experimental models for the risk assessment of antibiotic-induced QT prolongation. Eur J Pharmacol 2008; 577:222-32. [PMID: 18074444 DOI: 10.1016/j.ejphar.2007.07.070] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The prolongation of the ventricular repolarization and proarrhythmic effects (Torsade de Pointes: TdP) of five reference antibiotics were compared in four in-vitro models. 1. Using the patch clamp technique on the human ether-a-gogo-related gene (HERG) current, the rank order for blockade of the HERG-current (IC(50)) was: sparfloxacin (44 microM)>telithromycin=moxifloxacin=erythromycin (+/-100 microM). 2. Assessing their effects on action potential duration (APD(90)) and incidence of early afterdepolarizations in isolated rabbit Purkinje fibers, the rank order was: sparfloxacin>moxifloxacin>telithromycin>erythromycin (prolongation of APD(90) at 100 microM: 83%, 48%, 33% and 17% from baseline compared to +5% with solvent, P<0.05, respectively). 3. Assessing the drug effects on the APD(60), triangulation, reverse use-dependency, and instability in isolated Langendorff-perfused rabbit hearts, the rank order was: moxifloxacin>erythromycin>sparfloxacin>telithromycin. 4. Assessing their torsadogenic potentials (scores of effects on QT-interval, peak of the T wave to end of T wave: T(p-e), T(p-e)/QT ratio, R wave on T wave (R on T) and TdP in isolated rabbit left ventricular wedge preparations, the rank order for their TdP risk score was: sparfloxacin>erythromycin>moxifloxacin>telithromycin. Additional experiments with grepafloxacin indicate that the rank order to detect grepafloxacin-induced long QT was the wedge preparation>the Purkinje fiber>HERG>the isolated heart, where the isolated heart was unable to detect grepafloxacin-induced APD prolongation. The present study demonstrates that the first three in-vitro models can be used to assess the ability of antibiotic compounds to delay ventricular repolarization. However, with respect to their known clinical effects on QT and TdP incidence, the wedge preparation appears to be more predictive and suitable for detecting torsadogenic action of antibiotics.
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Affiliation(s)
- Hua Rong Lu
- Center of Excellence for Cardiovascular Safety Research, Johnson & Johnson Pharmaceutical Research and Development, Division of Janssen Pharmaceutica N.V. B-2340, Beerse, Belgium.
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Lu HR, Vlaminckx E, Van de Water A, Rohrbacher J, Hermans A, Gallacher DJ. In-vitro experimental models for the risk assessment of antibiotic-induced QT prolongation. Eur J Pharmacol 2006; 553:229-39. [PMID: 17054943 DOI: 10.1016/j.ejphar.2006.09.035] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Revised: 09/06/2006] [Accepted: 09/12/2006] [Indexed: 11/27/2022]
Abstract
The prolongation of the ventricular repolarization and proarrhythmic effects (Torsade de Pointes: TdP) of five reference antibiotics were compared in four in-vitro models. 1. Using the patch clamp technique on the human ether-a-gogo-related gene (HERG) current, the rank order for blockade of the HERG-current (IC(50)) was: sparfloxacin (44 microM)>telithromycin=moxifloxacin=erythromycin (+/-100 microM). 2. Assessing their effects on action potential duration (APD(90)) and incidence of early afterdepolarizations in isolated rabbit Purkinje fibers, the rank order was: sparfloxacin>moxifloxacin>telithromycin>erythromycin (prolongation of APD(90) at 100 microM: 83%, 48%, 33% and 17% from baseline compared to +5% with solvent, P<0.05, respectively). 3. Assessing the drug effects on the APD(60), triangulation, reverse use-dependency, and instability in isolated Langendorff-perfused rabbit hearts, the rank order was: moxifloxacin>erythromycin>sparfloxacin>telithromycin. 4. Assessing their torsadogenic potentials (scores of effects on QT-interval, peak of the T wave to end of T wave: T(p-e), T(p-e)/QT ratio, R wave on T wave (R on T) and TdP in isolated rabbit left ventricular wedge preparations, the rank order for their TdP risk score was: sparfloxacin>erythromycin>moxifloxacin>telithromycin. Additional experiments with grepafloxacin indicate that the rank order to detect grepafloxacin-induced long QT was the wedge preparation>the Purkinje fiber>HERG>the isolated heart, where the isolated heart was unable to detect grepafloxacin-induced APD prolongation. The present study demonstrates that the first three in-vitro models can be used to assess the ability of antibiotic compounds to delay ventricular repolarization. However, with respect to their known clinical effects on QT and TdP incidence, the wedge preparation appears to be more predictive and suitable for detecting torsadogenic action of antibiotics.
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Affiliation(s)
- Hua Rong Lu
- Center of Excellence for Cardiovascular Safety Research, Johnson and Johnson Pharmaceutical Research and Development, a Division of Janssen Pharmaceutica N.V. B-2340, Beerse, Belgium.
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Dubin AE, Nasser N, Rohrbacher J, Hermans AN, Marrannes R, Grantham C, Van Rossem K, Cik M, Chaplan SR, Gallacher D, Xu J, Guia A, Byrne NG, Mathes C. Identifying modulators of hERG channel activity using the PatchXpress planar patch clamp. ACTA ACUST UNITED AC 2005; 10:168-81. [PMID: 15799960 DOI: 10.1177/1087057104272295] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The authors used the PatchXpress 7000A system to measure compound activity at the hERG channel using procedures that mimicked the "gold-standard" conventional whole-cell patch clamp. A set of 70 compounds, including hERG antagonists with potencies spanning 3 orders of magnitude, were tested on hERG302-HEK cells using protocols aimed at either identifying compound activity at a single concentration or obtaining compound potency from a cumulative concentration dependence paradigm. After exposure to compounds and subsequent washout of the wells to determine reversibility of the block, blockade by a reference compound served as a quality control. Electrical parameters and voltage dependence were similar to those obtained using a conventional whole-cell patch clamp. Rank order of compound potency was also comparable to that determined by conventional methods. One exception was flunarizine, a particularly lipophilic compound. The PatchXpress accurately identified the activity of 29 moderately potent antagonists, which only weakly displace radiolabeled astemizole and are false negatives in the binding assay. Finally, no false hits were observed from a collection of relatively inactive compounds. High-quality data acquisition by PatchXpress should help accelerate secondary screening for ion channel modulators and the drug discovery process.
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Affiliation(s)
- Adrienne E Dubin
- Pain and Related Disorders, Johnson and Johnson Pharmaceutical Research and Development, San Diego, CA 92121, USA.
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Rohrbacher J, Ichinohe N, Kitai ST. Electrophysiological characteristics of substantia nigra neurons in organotypic cultures: spontaneous and evoked activities. Neuroscience 2000; 97:703-14. [PMID: 10842015 DOI: 10.1016/s0306-4522(00)00046-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Morphological and electrophysiological characteristics of dopaminergic and non-dopaminergic neurons in the substantia nigra and their postsynaptic responses to stimulation of the tegmental pedunculopontine nucleus were studied in rat organotypic triple cultures. These cultures consisted of the subthalamic nucleus explant, ventral mesencephalic explant, inclusive of the substantia nigra and the mesopontine tegmentum explant, inclusive of the tegmental pedunculopontine nucleus, prepared from one- to two-day-old rats. Intracellular sharp and whole-cell recordings were obtained from three- to eight-week-old organotypic cultures. Recorded neurons were identified as dopaminergic and non-dopaminergic neurons with tyrosine hydroxylase immunohistochemistry. Dopaminergic neurons had long duration action potentials, prominent afterhyperpolarization, time-dependent inward and outward rectification and strong frequency adaptation. Spontaneous firing patterns varied from regular, irregular to burst firing. Non-dopaminergic neurons had short duration action potentials, in general no rectifying currents, and maintained high firing frequencies. Spontaneous firing patterns in these neurons were irregular or burst firing. Morphological analysis of the recorded neurons labeled with neurobiotin revealed that non-dopaminergic neurons had more extensive arborization of higher-order dendrites than dopaminergic neurons. Dopaminergic and non-dopaminergic neurons receive glutamatergic and cholinergic excitatory inputs from the tegmental pedunculopontine nucleus. These results indicate that morphological and electrophysiological characteristics of substantia nigra neurons in the organotypic culture are generally similar to those reported in in vitro slice and in vivo studies. However, spontaneous activities of dopamine neurons observed in the organotypic culture preparation more closely resemble those in in vivo preparation compared to in vitro preparation.
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Affiliation(s)
- J Rohrbacher
- University of Tennessee, College of Medicine, Department of Anatomy and Neurobiology, TN 38163, Memphis, USA
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Rohrbacher J, Sauer K, Lewen A, Misgeld U. Enhancement of synaptic excitation by GABAA receptor antagonists in rat embryonic midbrain culture. J Neurophysiol 1998; 79:1113-6. [PMID: 9463468 DOI: 10.1152/jn.1998.79.2.1113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Alterations of synaptic excitation induced by exposure to gamma-aminobutyric acid-A (GABAA) receptor antagonists were investigated employing tight-seal whole cell recording from single neurons or pairs of neurons in rat embryonic midbrain culture. Application of GABAA receptor antagonists led to sustained depolarizations followed by synchronous paroxysmal depolarization shifts (PDSs). PDSs induced a transient increase in miniature excitatory postsynaptic currents in the presence as well as in the absence of a N-methyl-aspartate receptor antagonist. The increase in glutamate release supports the excitatory drive required to reinitiate PDSs from the quiescent interburst intervals. After washout of GABAA receptor antagonists, synaptic activity remained grouped, regardless of the presence or absence of PDS blockade by tetrodotoxin (TTX). Impediment of action potential-triggered transmitter release by Cd2+ or TTX also induced grouped activity. We conclude that changes in synaptic excitation are produced by the impaired GABAA inhibition per se and by the initiation of PDSs.
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Affiliation(s)
- J Rohrbacher
- Physiologisches Institut der Universität Heidelberg, D-69120 Heidelberg, Germany
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Rohrbacher J, Jarolimek W, Lewen A, Misgeld U. GABAB receptor-mediated inhibition of spontaneous inhibitory synaptic currents in rat midbrain culture. J Physiol 1997; 500 ( Pt 3):739-49. [PMID: 9161988 PMCID: PMC1159421 DOI: 10.1113/jphysiol.1997.sp022055] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
1. Tight-seal, whole-cell recording was used to study GABAB receptor-mediated inhibition of spontaneous inhibitory synaptic currents in cultured rat midbrain neurones. 2. Spontaneous miniature inhibitory postsynaptic currents (mIPSCs) were recorded in tetrodotoxin (TTX), Cd2+ and Ba2+. (R)-(-)-baclofen reduced the frequency of mIPSCs through a presynaptic mechanism. The EC50 for this effect was 7 microM. It was antagonized by the GABAB receptor antagonist CGP55845A (0.5 microM). 3. In pertussis toxin (PTX)-treated cultures, some GABAB receptor-mediated reduction of the frequency of mIPSCs persisted. In contrast, PTX treatment totally abolished inhibition of miniature excitatory postsynaptic currents (mEPSCs). 4. In PTX-treated cultures, a saturating concentration of (R)-(-)-baclofen inhibited action potential-generated IPSCs but no EPSCs. 5. PTX treatment abolished the (R)-(-)-baclofen-mediated inhibition of high voltage-activated somatic Ca2+ currents and of spontaneous IPSCs depending on presynaptic Ca2+ entry. 6. We conclude that cellular mechanisms underlying GABAB receptor-mediated inhibition of mIPSCs contribute to auto-inhibition of GABA release.
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Affiliation(s)
- J Rohrbacher
- I. Institute of Physiology, University of Heidelberg, Germany
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Radnikow G, Rohrbacher J, Misgeld U. Heterogeneity in use-dependent depression of inhibitory postsynaptic potentials in the rat neostriatum in vitro. J Neurophysiol 1997; 77:427-34. [PMID: 9120583 DOI: 10.1152/jn.1997.77.1.427] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
"Minimal stimulation" was applied to evoke responses in an "all-or-none" fashion in presumed medium spiny neurons of rat neostriatal slices in the presence of antagonists for glutamatergic excitation. For comparison, responses were evoked in the same cells by compound stimulation. Bicuculline (30 microM) blocked responses evoked by minimal stimulation, indicating that they were gamma-aminobutyric acid-A (GABAA)-receptor-mediated inhibitory postsynaptic potentials (IPSPS), whereas responses evoked by compound stimulation were only reduced in amplitude. Likewise, R(-)baclofen (1-20 microM) blocked IPSPS evoked by minimal stimulation in all but one cell. On the contrary, responses evoked by compound stimulation were always reduced in amplitude but never blocked. Paired-pulse depression (PPD) of averaged responses to minimal and compound stimulation was observed at a stimulus interval of 300 ms. The GABAB receptor antagonist CGP55845A (0.5 microM) had no effect on PPD evoked by compound stimulation but abolished PPD evoked by minimal stimulation. In a second set of experiments, the two stimulation paradigms were used to evoke responses in neostriatal slices continuously bathed in R(-)baclofen (10-20 microM). In R(-)baclofen a strong PPD was evoked by minimal and by compound stimulation. The amplitude of the response to compound stimulation increased on application of CGP55845A (0.5 microM). At the same time, PPD evoked by compound stimulation decreased. On the contrary, IPSP amplitude and PPD evoked by minimal stimulation remained unchanged. We conclude that two types of GABAergic terminals exist in the rat neostriatum, only one of which is regulated by GABAB receptors. However, the other class of terminals, not regulated by GABAB receptors, displays a much more pronounced PPD.
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Affiliation(s)
- G Radnikow
- I. Physiologisches Institut, Universität Heidelberg, Germany
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Rohrbacher J, Krieglstein K, Honerkamp S, Lewen A, Misgeld U. 5,7-Dihydroxytryptamine uptake discriminates living serotonergic cells from dopaminergic cells in rat midbrain culture. Neurosci Lett 1995; 199:207-10. [PMID: 8577399 DOI: 10.1016/0304-3940(95)12060-h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Dissociated cells from embryonic rat midbrain develop in dissociated culture into glutamatergic, GABAergic and aminergic cells. The autofluorescent serotonin analogue, 5,7-dihydroxytryptamine (5,7-DHT), is taken up by a small population of cells that is immunoreactive to 5-hydroxytryptamine. Tyrosine hydroxylase-immunoreactive cells do not accumulate 5,7-DHT. 5,7-DHT uptake, therefore, is well suited for the identification of living serotonergic cells and their discrimination from dopaminergic cells.
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Affiliation(s)
- J Rohrbacher
- I. Physiologisches Institut, Universität Heidelberg, Germany
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Abstract
The competitive N-methyl-D-aspartate (NMDA) receptor antagonists, DL-(E)-2-amino-4-methyl-5-phosphono-3-pentanoic acid (CGP 37849) and D(-)-2-amino-5-phosphonovaleric acid (APV), and the non-competitive NMDA antagonists, memantine and amantadine, which are used in the treatment of Parkinson's disease, were tested for their effects on intrastriatally evoked excitatory postsynaptic potentials (EPSPs) in rat neostriatal slices. Fast, non-NMDA receptor mediated synaptic excitation was not affected by any of the NMDA receptor antagonists. The NMDA component of the EPSPs was more prominent following reduction of the non-NMDA component of the EPSP by the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 5-10 microM). Memantine (30 microM) and amantadine (100 microM) had similar effects in reducing the NMDA component, but were not as effective as CGP 37849 (1-5 microM) or APV (10 microM). The data are compatible with a possible locus of action of memantine and amantadine in the neostriatum.
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Affiliation(s)
- J Rohrbacher
- I. Physiologisches Institut, Universität Heidelberg, Germany
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