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Yoon SH, Lee HL, Jeong DU, Lim KM, Park SJ, Kim KS. Assessment of the proarrhythmic effects of repurposed antimalarials for COVID-19 treatment using a comprehensive in vitro proarrhythmia assay (CiPA). Front Pharmacol 2023; 14:1220796. [PMID: 37649890 PMCID: PMC10464612 DOI: 10.3389/fphar.2023.1220796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 08/07/2023] [Indexed: 09/01/2023] Open
Abstract
Due to the outbreak of the SARS-CoV-2 virus, drug repurposing and Emergency Use Authorization have been proposed to treat the coronavirus disease 2019 (COVID-19) during the pandemic. While the efficiency of the drugs has been discussed, it was identified that certain compounds, such as chloroquine and hydroxychloroquine, cause QT interval prolongation and potential cardiotoxic effects. Drug-induced cardiotoxicity and QT prolongation may lead to life-threatening arrhythmias such as torsades de pointes (TdP), a potentially fatal arrhythmic symptom. Here, we evaluated the risk of repurposed pyronaridine or artesunate-mediated cardiac arrhythmias alone and in combination for COVID-19 treatment through in vitro and in silico investigations using the Comprehensive in vitro Proarrhythmia Assay (CiPA) initiative. The potential effects of each drug or in combinations on cardiac action potential (AP) and ion channels were explored using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and Chinese hamster ovary (CHO) cells transiently expressing cardiac ion channels (Nav1.5, Cav1.2, and hERG). We also performed in silico computer simulation using the optimized O'Hara-Rudy human ventricular myocyte model (ORd model) to classify TdP risk. Artesunate and dihydroartemisinin (DHA), the active metabolite of artesunate, are classified as a low risk of inducing TdP based on the torsade metric score (TMS). Moreover, artesunate does not significantly affect the cardiac APs of hiPSC-CMs even at concentrations up to 100 times the maximum serum concentration (Cmax). DHA modestly prolonged at APD90 (10.16%) at 100 times the Cmax. When considering Cmax, pyronaridine, and the combination of both drugs (pyronaridine and artesunate) are classified as having an intermediate risk of inducing TdP. However, when considering the unbound concentration (the free fraction not bound to carrier proteins or other tissues inducing pharmacological activity), both drugs are classified as having a low risk of inducing TdP. In summary, pyronaridine, artesunate, and a combination of both drugs have been confirmed to pose a low proarrhythmogenic risk at therapeutic and supratherapeutic (up to 4 times) free Cmax. Additionally, the CiPA initiative may be suitable for regulatory use and provide novel insights for evaluating drug-induced cardiotoxicity.
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Affiliation(s)
- Seung-Hyun Yoon
- R&D Center for Advanced Pharmaceuticals and Evaluation, Korea Institute of Toxicology, Daejeon, Republic of Korea
- College of Veterinary Medicine, Research Institute of Veterinary Medicine, Chungnam National University, Daejeon, Republic of Korea
| | - Hyun-Lee Lee
- R&D Center for Advanced Pharmaceuticals and Evaluation, Korea Institute of Toxicology, Daejeon, Republic of Korea
| | - Da Un Jeong
- Intelligent Human Twin Research Center, Electronics and Telecommunications Research Institute, Daejeon, Republic of Korea
| | - Ki Moo Lim
- Department of IT Convergence Engineering, Kumoh National Institute of Technology, Gumi, Republic of Korea
| | - Seong-Jun Park
- College of Veterinary Medicine, Research Institute of Veterinary Medicine, Chungnam National University, Daejeon, Republic of Korea
| | - Ki-Suk Kim
- R&D Center for Advanced Pharmaceuticals and Evaluation, Korea Institute of Toxicology, Daejeon, Republic of Korea
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Lother A, Kohl P. The heterocellular heart: identities, interactions, and implications for cardiology. Basic Res Cardiol 2023; 118:30. [PMID: 37495826 PMCID: PMC10371928 DOI: 10.1007/s00395-023-01000-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/17/2023] [Accepted: 07/17/2023] [Indexed: 07/28/2023]
Abstract
The heterocellular nature of the heart has been receiving increasing attention in recent years. In addition to cardiomyocytes as the prototypical cell type of the heart, non-myocytes such as endothelial cells, fibroblasts, or immune cells are coming more into focus. The rise of single-cell sequencing technologies enables identification of ever more subtle differences and has reignited the question of what defines a cell's identity. Here we provide an overview of the major cardiac cell types, describe their roles in homeostasis, and outline recent findings on non-canonical functions that may be of relevance for cardiology. We highlight modes of biochemical and biophysical interactions between different cardiac cell types and discuss the potential implications of the heterocellular nature of the heart for basic research and therapeutic interventions.
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Affiliation(s)
- Achim Lother
- Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, Albertstr. 25, 79104, Freiburg, Germany.
- Interdisciplinary Medical Intensive Care, Faculty of Medicine, Medical Center-University of Freiburg, University of Freiburg, Freiburg, Germany.
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, Faculty of Medicine, University Heart Center, University of Freiburg, Freiburg, Germany
- CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
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Jiang T, Ma X, Chen H, Jia H, Xiong Y. Diazepam ameliorated myocardial ischemia-reperfusion injury via inhibition of C-C chemokine receptor type 2/Tumor necrosis factor-alpha/Interleukins and Bcl-2-associated X protein/Caspase-3 pathways in experimental rats. J Vet Med Sci 2021; 83:1965-1976. [PMID: 34719607 PMCID: PMC8762406 DOI: 10.1292/jvms.21-0344] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Myocardial ischemia-reperfusion injury (IRI) is one of the most leading concerns for
public health globally. Diazepam, a local anesthetic, has been reported for its
cardioprotective potential. The present investigation aimed to evaluate the possible
mechanism of action of diazepam against left anterior descending ligation-induced
myocardial IRI in experimental rats. IRI was induced in healthy male rats by ligating
coronary artery for 30 min and then reperfused for 60 min. The animals were pre-treated
with either vehicle or diltiazem (10 mg/kg) or diazepam (1, 2.5, and 5 mg/kg) for 14 days.
Compared to the IRI group, diazepam (2.5 and 5 mg/kg) markedly
(P<0.05) attenuated IRI-induced alterations in cardiac function and
oxido-nitrosative stress. In addition, diazepam prominently (P<0.05)
improved cardiac Na+K+ATPase, Ca2+ATPase levels and
hypoxia-inducible factor-1 alpha (HIF-1α) mRNA expression. It also significantly
(P<0.05) down-regulated cardiac mRNA expressions of cardiac troponin
I (cTn-I), C-C chemokine receptor type 2 (CCR2), tumor necrosis factor-alpha (TNF-α),
interleukins (IL)-1β, and IL-6. In western blot analysis, IRI-induced myocardial apoptosis
was reduced by diazepam treatment reflected by a marked (P<0.05)
decreased in Bcl-2-associated X protein (Bax) and Caspase-3 protein expression. Diazepam
also efficiently (P<0.05) improved IRI-induced histological aberration
in cardiac tissue. In conclusion, diazepam exerts cardioprotective effect by inhibiting
inflammatory release (CCR2, TNF-α, and ILs), oxido-nitrosative stress, and apoptosis (Bax
and Caspase-3) pathway during myocardial IRI in experimental rats.
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Affiliation(s)
| | | | | | | | - Ying Xiong
- Department of Anesthesiology, 3201 Hospital
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Madden JC, Pawar G, Cronin MT, Webb S, Tan YM, Paini A. In silico resources to assist in the development and evaluation of physiologically-based kinetic models. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.comtox.2019.03.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Polak S, Tylutki Z, Holbrook M, Wiśniowska B. Better prediction of the local concentration-effect relationship: the role of physiologically based pharmacokinetics and quantitative systems pharmacology and toxicology in the evolution of model-informed drug discovery and development. Drug Discov Today 2019; 24:1344-1354. [PMID: 31132414 DOI: 10.1016/j.drudis.2019.05.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 03/04/2019] [Accepted: 05/21/2019] [Indexed: 12/15/2022]
Abstract
Model-informed drug discovery and development (MID3) is an umbrella term under which sit several computational approaches: quantitative systems pharmacology (QSP), quantitative systems toxicology (QST) and physiologically based pharmacokinetics (PBPK). QSP models are built using mechanistic knowledge of the pharmacological pathway focusing on the putative mechanism of drug efficacy; whereas QST models focus on safety and toxicity issues and the molecular pathways and networks that drive these adverse effects. These can be mediated through exaggerated on-target or off-target pharmacology, immunogenicity or the physiochemical nature of the compound. PBPK models provide a mechanistic description of individual organs and tissues to allow the prediction of the intra- and extra-cellular concentration of the parent drug and metabolites under different conditions. Information on biophase concentration enables the prediction of a drug effect in different organs and assessment of the potential for drug-drug interactions. Together, these modelling approaches can inform the exposure-response relationship and hence support hypothesis generation and testing, compound selection, hazard identification and risk assessment through to clinical proof of concept (POC) and beyond to the market.
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Affiliation(s)
- Sebastian Polak
- Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9 Street, 30-688 Kraków, Poland; Certara-Simcyp, Level 2-Acero, 1 Concourse Way, Sheffield, S1 2BJ, UK.
| | - Zofia Tylutki
- Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9 Street, 30-688 Kraków, Poland; Certara-Simcyp, Level 2-Acero, 1 Concourse Way, Sheffield, S1 2BJ, UK
| | - Mark Holbrook
- Certara-Simcyp, Level 2-Acero, 1 Concourse Way, Sheffield, S1 2BJ, UK
| | - Barbara Wiśniowska
- Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9 Street, 30-688 Kraków, Poland
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Hausner EA, Elmore SA, Yang X. Overview of the Components of Cardiac Metabolism. Drug Metab Dispos 2019; 47:673-688. [PMID: 30967471 PMCID: PMC7333657 DOI: 10.1124/dmd.119.086611] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 03/26/2019] [Indexed: 12/20/2022] Open
Abstract
Metabolism in organs other than the liver and kidneys may play a significant role in how a specific organ responds to chemicals. The heart has metabolic capability for energy production and homeostasis. This homeostatic machinery can also process xenobiotics. Cardiac metabolism includes the expression of numerous organic anion transporters, organic cation transporters, organic carnitine (zwitterion) transporters, and ATP-binding cassette transporters. Expression and distribution of the transporters within the heart may vary, depending on the patient’s age, disease, endocrine status, and various other factors. Several cytochrome P450 (P450) enzyme classes have been identified within the heart. The P450 hydroxylases and epoxygenases within the heart produce hydroxyeicosatetraneoic acids and epoxyeicosatrienoic acids, metabolites of arachidonic acid, which are critical in regulating homeostatic processes of the heart. The susceptibility of the cardiac P450 system to induction and inhibition from exogenous materials is an area of expanding knowledge, as are the metabolic processes of glucuronidation and sulfation in the heart. The susceptibility of various transcription factors and signaling pathways of the heart to disruption by xenobiotics is not fully characterized but is an area with implications for disruption of normal postnatal development, as well as modulation of adult cardiac health. There are knowledge gaps in the timelines of physiologic maturation and deterioration of cardiac metabolism. Cross-species characterization of cardiac-specific metabolism is needed for nonclinical work of optimum translational value to predict possible adverse effects, identify sensitive developmental windows for the design and conduct of informative nonclinical and clinical studies, and explore the possibilities of organ-specific therapeutics.
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Affiliation(s)
- Elizabeth A Hausner
- United States Food and Drug Administration, Center for Drug Evaluation and Research, Silver Spring, Maryland (E.A.H., X.Y.); and National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina (S.A.E.)
| | - Susan A Elmore
- United States Food and Drug Administration, Center for Drug Evaluation and Research, Silver Spring, Maryland (E.A.H., X.Y.); and National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina (S.A.E.)
| | - Xi Yang
- United States Food and Drug Administration, Center for Drug Evaluation and Research, Silver Spring, Maryland (E.A.H., X.Y.); and National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina (S.A.E.)
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Mikkelsen CR, Jornil JR, Andersen LV, Banner J, Hasselstrøm JB. Distribution of Eight QT-Prolonging Drugs and Their Main Metabolites Between Postmortem Cardiac Tissue and Blood Reveals Potential Pitfalls in Toxicological Interpretation. J Anal Toxicol 2019; 42:375-383. [PMID: 29579279 DOI: 10.1093/jat/bky018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 02/12/2018] [Indexed: 12/13/2022] Open
Abstract
Femoral blood concentrations are usually used in postmortem toxicology to assess possible toxic effects of drugs. This includes QT-prolongation and other cardiac dysrhythmia, which could have been the cause of death. However, blood concentration is only a surrogate for the active site concentration, and therefore cardiac tissue concentration may provide a more accurate toxicological interpretation. Thus, cardiac tissue and femoral and cardiac blood concentrations were examined for eight frequently used QT-prolonging drugs (QTD) and their metabolites in a mentally ill population. In total, 180 cases were included from the Danish autopsy-based forensic study SURVIVE. The concentrations were analyzed using ultra-performance liquid chromatography coupled with tandem mass spectrometry utilizing stable isotopically labeled internal standards. The results showed that the cardiac tissue concentrations were significantly higher compared to femoral and cardiac blood concentrations, with two exceptions. The median cardiac tissue-to-femoral blood concentration ratio (Kb) ranged from 2.2 (venlafaxine) to 15 (nortriptyline). The inter-individual fold difference between the minimum and maximum Kb ranged from 2.6-fold (Z-hydroxynortriptyline) to 61 (venlafaxine). For 12 compounds, postmortem redistribution appeared to be minimal, whereas four compounds displayed some degree of postmortem redistribution. Citalopram and quetiapine were selected for in-depth analysis of the relation between the toxicological interpretation and femoral blood/cardiac tissue concentrations. Within this dataset, citalopram displayed a wide overlap in cardiac tissue concentrations (~50%) between non-toxic and toxic citalopram cases, as estimated from femoral blood concentrations. In contrast, quetiapine displayed no overlap in cardiac tissue concentrations between non-toxic and toxic quetiapine cases based on femoral blood concentrations. The implication of the citalopram finding is that possible intoxications can be overlooked when only considering femoral blood concentrations. Based on the present findings, non-toxic cardiac tissue 10th-90th percentile concentration ranges were estimated for citalopram (0.93-4.4 mg/kg) and quetiapine (0.0073-0.60 mg/kg).
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Affiliation(s)
- Christian R Mikkelsen
- Section of Forensic Chemistry, Department of Forensic Medicine, Aarhus University, Palle Juul-Jensens Boulevard 99, Aarhus, Denmark
| | - Jakob R Jornil
- Section of Forensic Chemistry, Department of Forensic Medicine, Aarhus University, Palle Juul-Jensens Boulevard 99, Aarhus, Denmark
| | - Ljubica V Andersen
- Section of Forensic Chemistry, Department of Forensic Medicine, Aarhus University, Palle Juul-Jensens Boulevard 99, Aarhus, Denmark.,Department of Clinical Pharmacology, Aarhus University, Wilhelm Meyers Allé 4, Aarhus C, Denmark
| | - Jytte Banner
- Section of Forensic Pathology, Department of Forensic Medicine, University of Copenhagen, Frederik V's Vej 11, Copenhagen, Denmark
| | - Jørgen B Hasselstrøm
- Section of Forensic Chemistry, Department of Forensic Medicine, Aarhus University, Palle Juul-Jensens Boulevard 99, Aarhus, Denmark
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Patel N, Wiśniowska B, Jamei M, Polak S. Real Patient and its Virtual Twin: Application of Quantitative Systems Toxicology Modelling in the Cardiac Safety Assessment of Citalopram. AAPS JOURNAL 2017; 20:6. [PMID: 29181593 DOI: 10.1208/s12248-017-0155-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 10/16/2017] [Indexed: 11/30/2022]
Abstract
A quantitative systems toxicology (QST) model for citalopram was established to simulate, in silico, a 'virtual twin' of a real patient to predict the occurrence of cardiotoxic events previously reported in patients under various clinical conditions. The QST model considers the effects of citalopram and its most notable electrophysiologically active primary (desmethylcitalopram) and secondary (didesmethylcitalopram) metabolites, on cardiac electrophysiology. The in vitro cardiac ion channel current inhibition data was coupled with the biophysically detailed model of human cardiac electrophysiology to investigate the impact of (i) the inhibition of multiple ion currents (IKr, IKs, ICaL); (ii) the inclusion of metabolites in the QST model; and (iii) unbound or total plasma as the operating drug concentration, in predicting clinically observed QT prolongation. The inclusion of multiple ion channel current inhibition and metabolites in the simulation with unbound plasma citalopram concentration provided the lowest prediction error. The predictive performance of the model was verified with three additional therapeutic and supra-therapeutic drug exposure clinical cases. The results indicate that considering only the hERG ion channel inhibition of only the parent drug is potentially misleading, and the inclusion of active metabolite data and the influence of other ion channel currents should be considered to improve the prediction of potential cardiac toxicity. Mechanistic modelling can help bridge the gaps existing in the quantitative translation from preclinical cardiac safety assessment to clinical toxicology. Moreover, this study shows that the QST models, in combination with appropriate drug and systems parameters, can pave the way towards personalised safety assessment.
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Affiliation(s)
- Nikunjkumar Patel
- Simcyp Limited, a Certara Company, Blades Enterprise Centre, John Street, Sheffield, S2 4SU, UK.,Faculty of Pharmacy, Jagiellonian University Medical College, Kraków, Poland
| | - Barbara Wiśniowska
- Faculty of Pharmacy, Jagiellonian University Medical College, Kraków, Poland
| | - Masoud Jamei
- Simcyp Limited, a Certara Company, Blades Enterprise Centre, John Street, Sheffield, S2 4SU, UK
| | - Sebastian Polak
- Simcyp Limited, a Certara Company, Blades Enterprise Centre, John Street, Sheffield, S2 4SU, UK. .,Faculty of Pharmacy, Jagiellonian University Medical College, Kraków, Poland.
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A four-compartment PBPK heart model accounting for cardiac metabolism - model development and application. Sci Rep 2017; 7:39494. [PMID: 28051093 PMCID: PMC5209692 DOI: 10.1038/srep39494] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 11/21/2016] [Indexed: 12/20/2022] Open
Abstract
In the field of cardiac drug efficacy and safety assessment, information on drug concentration in heart tissue is desirable. Because measuring drug concentrations in human cardiac tissue is challenging in healthy volunteers, mathematical models are used to cope with such limitations. With a goal of predicting drug concentration in cardiac tissue, we have developed a whole-body PBPK model consisting of seventeen perfusion-limited compartments. The proposed PBPK heart model consisted of four compartments: the epicardium, midmyocardium, endocardium, and pericardial fluid, and accounted for cardiac metabolism using CYP450. The model was written in R. The plasma:tissues partition coefficients (Kp) were calculated in Simcyp Simulator. The model was fitted to the concentrations of amitriptyline in plasma and the heart. The estimated parameters were as follows: 0.80 for the absorption rate [h−1], 52.6 for Kprest, 0.01 for the blood flow through the pericardial fluid [L/h], and 0.78 for the P-parameter describing the diffusion between the pericardial fluid and epicardium [L/h]. The total cardiac clearance of amitriptyline was calculated as 0.316 L/h. Although the model needs further improvement, the results support its feasibility, and it is a first attempt to provide an active drug concentration in various locations within heart tissue using a PBPK approach.
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George CH, Mitchell AN, Preece R, Bannister ML, Yousef Z. Pleiotropic mechanisms of action of perhexiline in heart failure. Expert Opin Ther Pat 2016; 26:1049-59. [PMID: 27455171 DOI: 10.1080/13543776.2016.1211111] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
INTRODUCTION The re-purposing of the anti-anginal drug perhexiline (PHX) has resulted in symptomatic improvements in heart failure (HF) patients. The inhibition of carnitine palmitoyltransferase-1 (CPT-1) has been proposed as the primary mechanism underlying the therapeutic benefit of PHX. This hypothesis is contentious. AREAS COVERED We reviewed the primary literature and patent landscape of PHX from its initial development in the 1960s through to its emergence as a drug beneficial for HF. We focused on its physico-chemistry, molecular targets, tissue accumulation and clinical dosing. EXPERT OPINION Dogma that the beneficial effects of PHX are due primarily to potent myocardial CPT-1 inhibition is not supported by the literature and all available evidence point to it being extremely unlikely that the major effects of PHX occur via this mechanism. In vivo PHX is much more likely to be an inhibitor of surface membrane ion channels and also to have effects on other components of cellular metabolism and reactive oxygen species (ROS) generation across the cardiovascular system. However, the possibility that minor effects of PHX on CPT-1 underpin disproportionately large effects on myocardial function cannot be entirely excluded, especially given the massive accumulation of the drug in heart tissue.
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Affiliation(s)
- Christopher H George
- a Wales Heart Research Institute, School of Medicine , Cardiff University , Cardiff , UK
| | - Alice N Mitchell
- a Wales Heart Research Institute, School of Medicine , Cardiff University , Cardiff , UK
| | - Ryan Preece
- a Wales Heart Research Institute, School of Medicine , Cardiff University , Cardiff , UK
| | - Mark L Bannister
- a Wales Heart Research Institute, School of Medicine , Cardiff University , Cardiff , UK
| | - Zaheer Yousef
- a Wales Heart Research Institute, School of Medicine , Cardiff University , Cardiff , UK
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Poulin P. A paradigm shift in pharmacokinetic-pharmacodynamic (PKPD) modeling: rule of thumb for estimating free drug level in tissue compared with plasma to guide drug design. J Pharm Sci 2015; 104:2359-68. [PMID: 25943586 DOI: 10.1002/jps.24468] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 04/07/2015] [Accepted: 04/07/2015] [Indexed: 01/04/2023]
Abstract
A basic assumption in pharmacokinetics-pharmacodynamics research is that the free drug concentration is similar in plasma and tissue, and, hence, in vitro plasma data can be used to estimate the in vivo condition in tissue. However, in a companion manuscript, it has been demonstrated that this assumption is violated for the ionized drugs. Nonetheless, these observations focus on in vitro static environments and do not challenge data with an in vivo dynamic system. Therefore, an extension from an in vitro to an in vivo system becomes the necessary next step. The objective of this study was to perform theoretical simulations of the free drug concentration in tissue and plasma by using a physiologically based pharmacokinetics (PBPK) model reproducing the in vivo conditions in human. Therefore, the effects of drug ionization, lipophilicity, and clearance have been taken into account in a dynamic system. This modeling exercise was performed as a proof of concept to demonstrate that free drug concentration in tissue and plasma may also differ in a dynamic system for passively permeable drugs that are ionized at the physiological pH. The PBPK model simulations indicated that free drug concentrations in tissue cells and plasma significantly differ for the ionized drugs because of the pH gradient effect between cells and interstitial space. Hence, a rule of thumb for potentially performing more accurate PBPK/PD modeling is suggested, which states that the free drug concentration in tissue and plasma will differ for the ionizable drugs in contrast to the neutral drugs. In addition to the pH gradient effect for the ionizable drugs, lipophilicity and clearance effects will increase or decrease the free drug concentration in tissue and plasma for each class of drugs; thus, higher will be the drug lipophilicity and clearance, lower would be the free drug concentration in plasma, and, hence, in tissue, in a dynamic in vivo system. Therefore, only considering the value of free fraction in plasma derived from a static in vitro environment might be biased to guide drug design (the old paradigm), and, hence, it is recommended to use a PBPK model to reproduce more accurately the in vivo condition in tissue (the new paradigm). This newly developed approach can be used to predict free drug concentration in diverse tissue compartments for small molecules in toxicology and pharmacology studies, which can be leveraged to optimize the pharmacokinetics drivers of tissue distribution based upon physicochemical and physiological input parameters in an attempt to optimize free drug level in tissue. Overall, this present study provides guidance on the application of plasma and tissue concentration information in PBPK/PD research in preclinical and clinical studies, which is in accordance with the recent literature.
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