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Cheng YJ, Wu Y, Wei HQ, Liao YJ, Qu LP, Pan YH, Liu LJ, Bi WT. A novel mutation in hERG gene associated with azithromycin-induced acquired long QT syndrome. Mol Biol Rep 2024; 51:520. [PMID: 38625436 DOI: 10.1007/s11033-024-09421-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 03/06/2024] [Indexed: 04/17/2024]
Abstract
BACKGROUND Mutations in human ether-à-go-go-related gene (hERG) potassium channels are closely associated with long QT syndrome (LQTS). Previous studies have demonstrated that macrolide antibiotics increase the risk of cardiovascular diseases. To date, the mechanisms underlying acquired LQTS remain elusive. METHODS A novel hERG mutation I1025N was identified in an azithromycin-treated patient with acquired long QT syndrome via Sanger sequencing. The mutant I1025N plasmid was transfected into HEK-293 cells, which were subsequently incubated with azithromycin. The effect of azithromycin and mutant I1025N on the hERG channel was evaluated via western blot, immunofluorescence, and electrophysiology techniques. RESULTS The protein expression of the mature hERG protein was down-regulated, whereas that of the immature hERG protein was up-regulated in mutant I1025N HEK-293 cells. Azithromycin administration resulted in a negative effect on the maturation of the hERG protein. Additionally, the I1025N mutation exerted an inhibitory effect on hERG channel current. Moreover, azithromycin inhibited hERG channel current in a concentration-dependent manner. The I1025N mutation and azithromycin synergistically decreased hERG channel expression and hERG current. However, the I1025N mutation and azithromycin did not alter channel gating dynamics. CONCLUSIONS These findings suggest that hERG gene mutations might be involved in the genetic susceptibility mechanism underlying acquired LQTS induced by azithromycin.
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Affiliation(s)
- Yun-Jiu Cheng
- Department of Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, China
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Yang Wu
- Department of Cardiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- NHC Key Laboratory of Assisted Circulation and Vascular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Hui-Qiang Wei
- Department of Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, China
| | - Yi-Jian Liao
- The First Clinical Medical College, Guangdong Medical University, Zhanjiang, China
| | - Li-Ping Qu
- Department of Cardiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- NHC Key Laboratory of Assisted Circulation and Vascular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Yue-Han Pan
- Department of Cardiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- NHC Key Laboratory of Assisted Circulation and Vascular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Li-Juan Liu
- Department of Cardiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
- NHC Key Laboratory of Assisted Circulation and Vascular Diseases, Sun Yat-sen University, Guangzhou, China.
| | - Wen-Tao Bi
- Department of Cardiovascular Medicine, People's Hospital of Macheng City, Macheng, China.
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El Harchi A, Hancox JC. hERG agonists pose challenges to web-based machine learning methods for prediction of drug-hERG channel interaction. J Pharmacol Toxicol Methods 2023; 123:107293. [PMID: 37468081 DOI: 10.1016/j.vascn.2023.107293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 05/23/2023] [Accepted: 07/12/2023] [Indexed: 07/21/2023]
Abstract
Pharmacological blockade of the IKr channel (hERG) by diverse drugs in clinical use is associated with the Long QT Syndrome that can lead to life threatening arrhythmia. Various computational tools including machine learning models (MLM) for the prediction of hERG inhibition have been developed to facilitate the throughput screening of drugs in development and optimise thus the prediction of hERG liabilities. The use of MLM relies on large libraries of training compounds for the quantitative structure-activity relationship (QSAR) modelling of hERG inhibition. The focus on inhibition omits potential effects of hERG channel agonist molecules and their associated QT shortening risk. It is instructive, therefore, to consider how known hERG agonists are handled by MLM. Here, two highly developed online computational tools for the prediction of hERG liability, Pred-hERG and HergSPred were probed for their ability to detect hERG activator drug molecules as hERG interactors. In total, 73 hERG blockers were tested with both computational tools giving overall good predictions for hERG blockers with reported IC50s below Pred-hERG and HergSPred cut-off threshold for hERG inhibition. However, for compounds with reported IC50s above this threshold such as disopyramide or sotalol discrepancies were observed. HergSPred identified all 20 hERG agonists selected as interacting with the hERG channel. Further studies are warranted to improve online MLM prediction of hERG related cardiotoxicity, by explicitly taking into account channel agonism as well as inhibition.
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Affiliation(s)
- Aziza El Harchi
- School of Physiology and Pharmacology and Neuroscience, Biomedical Sciences Building, The University of Bristol, University Walk, Bristol BS8 1TD, UK.
| | - Jules C Hancox
- School of Physiology and Pharmacology and Neuroscience, Biomedical Sciences Building, The University of Bristol, University Walk, Bristol BS8 1TD, UK
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3
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Pivonello R, Zacharieva S, Elenkova A, Tóth M, Shimon I, Stigliano A, Badiu C, Brue T, Georgescu CE, Tsagarakis S, Cohen F, Fleseriu M. Levoketoconazole in the treatment of patients with endogenous Cushing's syndrome: a double-blind, placebo-controlled, randomized withdrawal study (LOGICS). Pituitary 2022; 25:911-926. [PMID: 36085339 PMCID: PMC9675660 DOI: 10.1007/s11102-022-01263-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/15/2022] [Indexed: 10/14/2022]
Abstract
PURPOSE The efficacy of levoketoconazole for endogenous Cushing's syndrome was demonstrated in a phase 3, open-label study (SONICS). This study (LOGICS) evaluated drug-specificity of cortisol normalization. METHODS LOGICS was a phase 3, placebo-controlled, randomized-withdrawal study with open-label titration-maintenance (14-19 weeks) followed by double-blind, randomized-withdrawal (~ 8 weeks), and restoration (~ 8 weeks) phases. RESULTS 79 patients received levoketoconazole during titration-maintenance; 39 patients on a stable dose (~ 4 weeks or more) proceeded to randomization. These and 5 SONICS completers who did not require dose titration were randomized to levoketoconazole (n = 22) or placebo (n = 22). All patients with loss of response (the primary endpoint) met the prespecified criterion of mean urinary free cortisol (mUFC) > 1.5 × upper limit of normal. During randomized-withdrawal, 21 patients withdrawn to placebo (95.5%) lost mUFC response compared with 9 patients continuing levoketoconazole (40.9%); treatment difference: - 54.5% (95% CI - 75.7, - 27.4; P = 0.0002). At the end of randomized-withdrawal, mUFC normalization was observed among 11 (50.0%) patients receiving levoketoconazole and 1 (4.5%) receiving placebo; treatment difference: 45.5% (95% CI 19.2, 67.9; P = 0.0015). Restoration of levoketoconazole reversed loss of cortisol control in most patients who had received placebo. Adverse events were reported in 89% of patients during treatment with levoketoconazole (dose-titration, randomized-withdrawal, and restoration phases combined), most commonly nausea (29%) and hypokalemia (26%). Prespecified adverse events of special interest with levoketoconazole were liver-related (10.7%), QT interval prolongation (10.7%), and adrenal insufficiency (9.5%). CONCLUSIONS Levoketoconazole reversibly normalized urinary cortisol in patients with Cushing's syndrome. No new risks of levoketoconazole treatment were identified.
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Affiliation(s)
| | | | | | | | - Ilan Shimon
- Rabin Medical Center and Tel Aviv University, Tel Aviv, Israel
| | | | - Corin Badiu
- National Institute of Endocrinology CI Parhon and "C. Davila" University of Medicine and Pharmacy, Bucharest, Romania
| | - Thierry Brue
- Aix-Marseille Université and Assistance Publique - Hôpitaux de Marseille, Hôpital de la Conception, Marseille, France
| | - Carmen Emanuela Georgescu
- Iuliu Haţieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
- Endocrinology Clinical Unit, Cluj County Emergency Hospital, Cluj-Napoca, Romania
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4
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Fleseriu M, Auchus RJ, Pivonello R, Salvatori R, Zacharieva S, Biller BMK. Levoketoconazole: a novel treatment for endogenous Cushing's syndrome. Expert Rev Endocrinol Metab 2021; 16:159-174. [PMID: 34380370 DOI: 10.1080/17446651.2021.1945440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 06/10/2021] [Indexed: 02/08/2023]
Abstract
Introduction: Endogenous Cushing's syndrome (CS) is a rare, life-threatening endocrine disorder that is caused by chronic exposure to cortisol overproduction. Levoketoconazole (Recorlev), a 2S, 4R stereoisomer of ketoconazole, is a steroidogenesis inhibitor under investigation for the treatment of CS.Areas covered: This review covers the pharmacology, efficacy, and safety of levoketoconazole for the treatment of patients with endogenous CS.Expert opinion: Based on the preclinical and clinical pharmacology findings, levoketoconazole appears to be the relevant enantiomer of ketoconazole for inhibition of steroidogenesis, with more potent inhibition of both cortisol and androgen synthesis relative to ketoconazole racemate and the 2R, 4S stereoisomer dextroketoconazole. Results from the phase III SONICS study showed that levoketoconazole was effective in normalizing cortisol levels and improving biomarkers of cardiovascular risk in a significant percentage of patients. In addition, treatment with levoketoconazole showed improvements in subjective clinical assessments of clinician-rated CS clinical signs and symptoms, patient-reported quality of life, and depression symptom severity. Testosterone levels decreased significantly in women. Levoketoconazole had an acceptable safety profile with no unexpected safety signals. The favorable pharmacology, efficacy, and safety profile of levoketoconazole supports its use as medical therapy for CS, if approved.
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Affiliation(s)
- Maria Fleseriu
- Oregon Health and Science University, Department of Medicine, Division of Endocrinology, Diabetes and Clinical Nutrition, Department of Neurological Surgery, and Pituitary Center, Portland, USA
| | - Richard J Auchus
- University of Michigan Medical School, Department of Internal Medicine and Department of Pharmacology, Ann Arbor, USA
| | - Rosario Pivonello
- Università Federico II Di Napoli, Dipartimento Di Medicina Clinica E Chirurgia, Sezione Di Endocrinologia, Naples, Italy
| | - Roberto Salvatori
- Johns Hopkins University, Department of Medicine, Division of Endocrinology, and Pituitary Center, Baltimore, USA
| | - Sabina Zacharieva
- Medical University-Sofia, Department of Endocrinology, Sofia, Bulgaria
| | - Beverly M K Biller
- Massachusetts General Hospital, Neuroendocrine and Pituitary Tumor Clinical Center, Boston, USA
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5
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Su S, Sun J, Wang Y, Xu Y. Cardiac hERG K + Channel as Safety and Pharmacological Target. Handb Exp Pharmacol 2021; 267:139-166. [PMID: 33829343 DOI: 10.1007/164_2021_455] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The human ether-á-go-go related gene (hERG, KCNH2) encodes the pore-forming subunit of the potassium channel responsible for a fast component of the cardiac delayed rectifier potassium current (IKr). Outward IKr is an important determinant of cardiac action potential (AP) repolarization and effectively controls the duration of the QT interval in humans. Dysfunction of hERG channel can cause severe ventricular arrhythmias and thus modulators of the channel, including hERG inhibitors and activators, continue to attract intense pharmacological interest. Certain inhibitors of hERG channel prolong the action potential duration (APD) and effective refractory period (ERP) to suppress premature ventricular contraction and are used as class III antiarrhythmic agents. However, a reduction of the hERG/IKr current has been recognized as a predominant mechanism responsible for the drug-induced delayed repolarization known as acquired long QT syndromes (LQTS), which is linked to an increased risk for "torsades de pointes" (TdP) ventricular arrhythmias and sudden cardiac death. Many drugs of different classes and structures have been identified to carry TdP risk. Hence, assessing hERG/IKr blockade of new drug candidates is mandatory in the drug development process according to the regulatory agencies. In contrast, several hERG channel activators have been shown to enhance IKr and shorten the APD and thus might have potential antiarrhythmic effects against pathological LQTS. However, these activators may also be proarrhythmic due to excessive shortening of APD and the ERP.
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Affiliation(s)
- Shi Su
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei, China
| | - Jinglei Sun
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei, China
| | - Yi Wang
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei, China
| | - Yanfang Xu
- Department of Pharmacology, Hebei Medical University, The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei, China.
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Mamoshina P, Rodriguez B, Bueno-Orovio A. Toward a broader view of mechanisms of drug cardiotoxicity. CELL REPORTS MEDICINE 2021; 2:100216. [PMID: 33763655 PMCID: PMC7974548 DOI: 10.1016/j.xcrm.2021.100216] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cardiotoxicity, defined as toxicity that affects the heart, is one of the most common adverse drug effects. Numerous drugs have been shown to have the potential to induce lethal arrhythmias by affecting cardiac electrophysiology, which is the focus of current preclinical testing. However, a substantial number of drugs can also affect cardiac function beyond electrophysiology. Within this broader sense of cardiotoxicity, this review discusses the key drug-protein interactions known to be involved in cardiotoxic drug response. We cover adverse effects of anticancer, central nervous system, genitourinary system, gastrointestinal, antihistaminic, anti-inflammatory, and anti-infective agents, illustrating that many share mechanisms of cardiotoxicity, including contractility, mitochondrial function, and cellular signaling.
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Affiliation(s)
| | - Blanca Rodriguez
- Department of Computer Science, BHF Centre of Research Excellence, University of Oxford, Oxford, UK
| | - Alfonso Bueno-Orovio
- Department of Computer Science, BHF Centre of Research Excellence, University of Oxford, Oxford, UK
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7
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Saponara S, Fusi F, Iovinelli D, Ahmed A, Trezza A, Spiga O, Sgaragli G, Valoti M. Flavonoids and hERG channels: Friends or foes? Eur J Pharmacol 2021; 899:174030. [PMID: 33727059 DOI: 10.1016/j.ejphar.2021.174030] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 02/28/2021] [Accepted: 03/11/2021] [Indexed: 01/24/2023]
Abstract
The cardiac action potential is regulated by several ion channels. Drugs capable to block these channels, in particular the human ether-à-go-go-related gene (hERG) channel, also known as KV11.1 channel, may lead to a potentially lethal ventricular tachyarrhythmia called "Torsades de Pointes". Thus, evaluation of the hERG channel off-target activity of novel chemical entities is nowadays required to safeguard patients as well as to avoid attrition in drug development. Flavonoids, a large class of natural compounds abundantly present in food, beverages, herbal medicines, and dietary food supplements, generally escape this assessment, though consumed in consistent amounts. Continuously growing evidence indicates that these compounds may interact with the hERG channel and block it. The present review, by examining numerous studies, summarizes the state-of-the-art in this field, describing the most significant examples of direct and indirect inhibition of the hERG channel current operated by flavonoids. A description of the molecular interactions between a few of these natural molecules and the Rattus norvegicus channel protein, achieved by an in silico approach, is also presented.
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Affiliation(s)
- Simona Saponara
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Fabio Fusi
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy.
| | - Daniele Iovinelli
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Amer Ahmed
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Alfonso Trezza
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Ottavia Spiga
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Giampietro Sgaragli
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy; Accademia Italiana della Vite e del Vino, via Logge degli Uffizi Corti 1, 50122, Florence, Italy
| | - Massimo Valoti
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy
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9
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Zequn Z, Yujia W, Dingding Q, Jiangfang L. Off-label use of chloroquine, hydroxychloroquine, azithromycin and lopinavir/ritonavir in COVID-19 risks prolonging the QT interval by targeting the hERG channel. Eur J Pharmacol 2020; 893:173813. [PMID: 33345848 PMCID: PMC7746509 DOI: 10.1016/j.ejphar.2020.173813] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 11/29/2020] [Accepted: 12/11/2020] [Indexed: 12/20/2022]
Abstract
Coronavirus disease-2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), poses an enormous challenge to the medical system, especially the lack of safe and effective COVID-19 treatment methods, forcing people to look for drugs that may have therapeutic effects as soon as possible. Some old drugs have shown clinical benefits after a few small clinical trials that attracted great attention. Clinically, however, many drugs, including those currently used in COVID-19, such as chloroquine, hydroxychloroquine, azithromycin, and lopinavir/ritonavir, may cause cardiotoxicity by acting on cardiac potassium channels, especially hERG channel through their off-target effects. The blocking of the hERG channel prolongs QT intervals on electrocardiograms; thus, it might induce severe ventricular arrhythmias and even sudden cardiac death. Therefore, while focusing on the efficacy of COVID-19 drugs, the fact that they block hERG channels to cause arrhythmias cannot be ignored. To develop safer and more effective drugs, it is necessary to understand the interactions between drugs and the hERG channel and the molecular mechanism behind this high affinity. In this review, we focus on the biochemical and molecular mechanistic aspects of drug-related blockade of the hERG channel to provide insights into QT prolongation caused by off-label use of related drugs in COVID-19, and hope to weigh the risks and benefits when using these drugs.
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Affiliation(s)
- Zheng Zequn
- Medical College, Ningbo University, Ningbo, Zhejiang, 315000, China
| | - Wu Yujia
- Medical College, Ningbo University, Ningbo, Zhejiang, 315000, China
| | - Qian Dingding
- Department of Cardiovascular, Lihuili Hospital Affiliated to Ningbo University, Ningbo, Zhejiang, 315211, China
| | - Lian Jiangfang
- Department of Cardiovascular, Lihuili Hospital Affiliated to Ningbo University, Ningbo, Zhejiang, 315211, China.
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Pashazadeh‐Panahi P, Hasanzadeh M, Eivazzadeh‐Keihan R. Spectrophotometric study of ketoconazole binding with citrate capped silver nanoparticles and its monitoring in human plasma samples. J Mol Recognit 2020; 33:e2830. [DOI: 10.1002/jmr.2830] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 11/22/2019] [Accepted: 12/04/2019] [Indexed: 11/08/2022]
Affiliation(s)
| | - Mohammad Hasanzadeh
- Pharmaceutical Analysis Research CenterTabriz University of Medical Sciences Tabriz Iran
| | - Reza Eivazzadeh‐Keihan
- Catalysts and Organic Synthesis Research LaboratoryDepartment of Chemistry, Iran University of Science and Technology Tehran Iran
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11
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Fleseriu M, Pivonello R, Elenkova A, Salvatori R, Auchus RJ, Feelders RA, Geer EB, Greenman Y, Witek P, Cohen F, Biller BMK. Efficacy and safety of levoketoconazole in the treatment of endogenous Cushing's syndrome (SONICS): a phase 3, multicentre, open-label, single-arm trial. Lancet Diabetes Endocrinol 2019; 7:855-865. [PMID: 31542384 DOI: 10.1016/s2213-8587(19)30313-4] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 08/12/2019] [Accepted: 08/13/2019] [Indexed: 01/16/2023]
Abstract
BACKGROUND Levoketoconazole is a ketoconazole stereoisomer in development for treatment of Cushing's syndrome and has not been assessed previously in a clinical trial in patients with Cushing's syndrome. We aimed to investigate the efficacy and safety of levoketoconazole in patients with endogenous Cushing's syndrome. METHODS SONICS is a phase 3, multicentre, open-label, non-randomised, single-arm study in which we recruited adults (≥18 years) with confirmed Cushing's syndrome and a mean 24-h urinary free cortisol (mUFC) of at least 1·5 times the upper limit of normal from 60 hospital and community sites in 19 countries (15 countries in Europe, and Canada, Israel, Turkey, and the USA). Patients were treated with oral levoketoconazole in a 2-21 week incremental dose-titration phase starting at 150 mg twice daily (150 mg increments until mUFC normalisation, maximum 600 mg twice daily) and a 6-month maintenance phase. The primary outcome was the proportion of patients with mUFC normalisation at end of maintenance, without dose increase during the maintenance phase (in the intention-to-treat population). Prespecified adverse events of special interest were potential liver toxicity, corrected QT prolongation, and adrenal insufficiency. This trial is registered with ClinicalTrials.gov, NCT01838551. FINDINGS Between July 30, 2014, and June 30, 2017, 201 individuals were screened and 94 patients were enrolled and received at least one dose of study medication. Of the 94 patients, 80 (85%) had pituitary Cushing's syndrome. Mean mUFC at baseline was 671·4 nmol/24 h (243·3 μg/24 h), which is 4·9 times the upper limit of normal. Of the 77 patients who advanced to the maintenance phase, 62 (81%) had mUFC normalisation by end-of-dose titration. At the end of the 6-month maintenance phase, 29 (31%) of 94 patients were responders; the least-squares mean estimate of the proportion of responders was 0·30 (95% CI 0·21-0·40; p=0·0154 vs null hypothesis of ≤0·20). The most common adverse events in the 94 patients were nausea (30 [32%]) and headache (26 [28%]). Adverse events led to study discontinuation in 12 (13%) of 94 patients. Two patients had a QT interval (Fridericia corrected) of more than 500 ms, and three patients had suspected adrenal insufficiency. Alanine aminotransferase reversibly increased to more than three times the upper limit of normal in ten (11%) patients. Four patients had serious adverse events that were considered probably or definitely related to the study drug: abnormal liver function test results (n=1), prolonged QT interval (n=2), and adrenal insufficiency (n=1). One person died from colon carcinoma unrelated to study medication. INTERPRETATION Twice-daily oral levoketoconazole treatment led to sustained improvements in urinary free cortisol, with an acceptable safety and tolerability profile. Levoketoconazole might represent a useful therapeutic option for the medical treatment of Cushing's syndrome. FUNDING Strongbridge Biopharma.
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Affiliation(s)
- Maria Fleseriu
- Department of Medicine and Neurological Surgery, Northwest Pituitary Center, Oregon Health & Science University, Portland, OR, USA.
| | - Rosario Pivonello
- Dipartimento di Medicina Clinica e Chirurgia, Sezione di Endocrinologia, Università di Napoli Federico II, Naples, Italy
| | - Atanaska Elenkova
- Department of Endocrinology, Medical University Sofia, Sofia, Bulgaria
| | - Roberto Salvatori
- Division of Endocrinology, Diabetes and Metabolism and Pituitary Center, Johns Hopkins University, Baltimore, MD, USA
| | - Richard J Auchus
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Richard A Feelders
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, Rotterdam, Netherlands
| | - Eliza B Geer
- Pituitary & Skull Base Tumor Center, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Yona Greenman
- Institute of Endocrinology and Metabolism, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel
| | - Przemyslaw Witek
- Department of Gastroenterology, Endocrinology and Internal Diseases, Military Institute of Medicine, Warsaw, Poland
| | | | - Beverly M K Biller
- Neuroendocrine Clinical Center, Massachusetts General Hospital, Boston, MA, USA
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12
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Molloy SF, Bradley J, Karunaharan N, Mputu M, Stone N, Phulusa J, Chawinga C, Gaskell K, Segula D, Ming D, Peirse M, Chanda D, Lakhi S, Loyse A, Kanyama C, Heyderman RS, Harrison TS. Effect of oral fluconazole 1200 mg/day on QT interval in African adults with HIV-associated cryptococcal meningitis. AIDS 2018; 32:2259-2261. [PMID: 30102652 PMCID: PMC6150187 DOI: 10.1097/qad.0000000000001961] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 06/27/2018] [Indexed: 11/25/2022]
Abstract
: We assessed the effect of fluconazole 1200 mg/day on the QT interval in cryptococcal meningitis patients. Mean corrected QT (QTc) change from baseline to day 7 was 10.1 ms (IQR: -28 to 46 ms) in the fluconazole treatment group and -12.6 ms (IQR: -39 to 13.5 ms) in those not taking fluconazole (P = 0.04). No significant increase in QTc measurements over 500 ms was observed with fluconazole. Nevertheless, it remains important to correct any electrolyte imbalance and avoid concomitant drugs that may increase QTc.
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Affiliation(s)
- Síle F. Molloy
- Centre for Global Health, Institute for Infection and Immunity, St George's University of London
- Joint first authors
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
- Joint first authors
| | - Natasha Karunaharan
- Centre for Global Health, Institute for Infection and Immunity, St George's University of London
| | - Muhammad Mputu
- University Teaching Hospital, Lusaka, Zambia
- University of Zambia School of Medicine, Lusaka, Zambia
| | - Neil Stone
- Centre for Global Health, Institute for Infection and Immunity, St George's University of London
| | - Jacob Phulusa
- University of North Carolina Project–Malawi, Kamuzu Central Hospital, Lilongwe
| | - Chimwemwe Chawinga
- University of North Carolina Project–Malawi, Kamuzu Central Hospital, Lilongwe
| | - Kate Gaskell
- Malawi–Liverpool–Wellcome Trust Clinical Research Programme, College of Medicine, University of Malawi, Malawi
| | - Dalitso Segula
- Malawi–Liverpool–Wellcome Trust Clinical Research Programme, College of Medicine, University of Malawi, Malawi
| | - Damien Ming
- Malawi–Liverpool–Wellcome Trust Clinical Research Programme, College of Medicine, University of Malawi, Malawi
| | - Mary Peirse
- Malawi–Liverpool–Wellcome Trust Clinical Research Programme, College of Medicine, University of Malawi, Malawi
| | - Duncan Chanda
- University Teaching Hospital, Lusaka, Zambia
- University of Zambia School of Medicine, Lusaka, Zambia
| | | | - Angela Loyse
- Centre for Global Health, Institute for Infection and Immunity, St George's University of London
| | - Cecilia Kanyama
- University of North Carolina Project–Malawi, Kamuzu Central Hospital, Lilongwe
| | - Robert S. Heyderman
- Malawi–Liverpool–Wellcome Trust Clinical Research Programme, College of Medicine, University of Malawi, Malawi
- University College London, London, UK
| | - Thomas S. Harrison
- Centre for Global Health, Institute for Infection and Immunity, St George's University of London
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13
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Wiśniowska B, Lisowski B, Kulig M, Polak S. Drug interaction at hERG channel: In vitro assessment of the electrophysiological consequences of drug combinations and comparison against theoretical models. J Appl Toxicol 2017; 38:450-458. [DOI: 10.1002/jat.3552] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 09/24/2017] [Accepted: 09/24/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Barbara Wiśniowska
- Pharmacoepidemiology and Pharmacoeconomics Unit, Faculty of Pharmacy; Jagiellonian University Medical College; Medyczna 9, Str., 30-688 Kraków Poland
| | - Bartosz Lisowski
- Pharmacoepidemiology and Pharmacoeconomics Unit, Faculty of Pharmacy; Jagiellonian University Medical College; Medyczna 9, Str., 30-688 Kraków Poland
- M. Smoluchowski Institute of Physics; Jagiellonian University; Kraków Poland
- Department of Biophysics; Jagiellonian University Medical College; Kraków Poland
| | - Magdalena Kulig
- Pharmacoepidemiology and Pharmacoeconomics Unit, Faculty of Pharmacy; Jagiellonian University Medical College; Medyczna 9, Str., 30-688 Kraków Poland
| | - Sebastian Polak
- Pharmacoepidemiology and Pharmacoeconomics Unit, Faculty of Pharmacy; Jagiellonian University Medical College; Medyczna 9, Str., 30-688 Kraków Poland
- Simcyp (part of Certara); S2 4SU Sheffield UK
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14
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Jeevaratnam K, Chadda KR, Huang CLH, Camm AJ. Cardiac Potassium Channels: Physiological Insights for Targeted Therapy. J Cardiovasc Pharmacol Ther 2017; 23:119-129. [PMID: 28946759 PMCID: PMC5808825 DOI: 10.1177/1074248417729880] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The development of novel drugs specifically directed at the ion channels underlying particular features of cardiac action potential (AP) initiation, recovery, and refractoriness would contribute to an optimized approach to antiarrhythmic therapy that minimizes potential cardiac and extracardiac toxicity. Of these, K+ channels contribute numerous and diverse currents with specific actions on different phases in the time course of AP repolarization. These features and their site-specific distribution make particular K+ channel types attractive therapeutic targets for the development of pharmacological agents attempting antiarrhythmic therapy in conditions such as atrial fibrillation. However, progress in the development of such temporally and spatially selective antiarrhythmic drugs against particular ion channels has been relatively limited, particularly in view of our incomplete understanding of the complex physiological roles and interactions of the various ionic currents. This review summarizes the physiological properties of the main cardiac potassium channels and the way in which they modulate cardiac electrical activity and then critiques a number of available potential antiarrhythmic drugs directed at them.
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Affiliation(s)
- Kamalan Jeevaratnam
- 1 Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,2 School of Medicine, Perdana University-Royal College of Surgeons Ireland, Serdang, Selangor Darul Ehsan, Malaysia
| | - Karan R Chadda
- 1 Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,3 Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Christopher L-H Huang
- 3 Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.,4 Division of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - A John Camm
- 5 Cardiac Clinical Academic Group, St George's Hospital Medical School, University of London, Cranmer Terrace, London, United Kingdom
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15
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Song T, Zhang Y, Song Q, Han X, Guan S, Zhang X, Chu X, Zhang F, Zhang J, Chu L. Bufalin, a bufanolide steroid from the parotoid glands of the Chinese toad, suppresses hERG K + currents expressed in HEK293 cells. Fundam Clin Pharmacol 2017; 31:695-700. [PMID: 28755515 DOI: 10.1111/fcp.12306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 07/21/2017] [Accepted: 07/26/2017] [Indexed: 01/16/2023]
Abstract
In this study, we investigated the effect of bufalin on the human ether-à-go-go-related gene (hERG) K+ channels using the perforated patch recording technique. We measured a half-maximal inhibitory concentration (IC50 ) of 24.83 μM and maximal inhibitory effect of 39.45 ± 1.14% with bufalin. These findings suggest that bufalin is a potent hERG K+ channel blocker and may provide a new way for understanding Chan Su-induced arrhythmia.
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Affiliation(s)
- Tao Song
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, 050200, Hebei, China
| | - Yuanyuan Zhang
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, 050200, Hebei, China.,Hebei key laboratory of integrative Medicine on Liver-Kidney Patterns, Shijiazhuang, 050200, Hebei, China
| | - Qiongtao Song
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, 050200, Hebei, China
| | - Xue Han
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, 050200, Hebei, China
| | - Shengjiang Guan
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, 050200, Hebei, China
| | - Xuan Zhang
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, 050200, Hebei, China.,Hebei key laboratory of integrative Medicine on Liver-Kidney Patterns, Shijiazhuang, 050200, Hebei, China
| | - Xi Chu
- Department of Pharmacy, The Fourth Hospital of Hebei Medical University, No. 12, Jiankang Road, Shijiazhuang, 050011, Hebei, China
| | - Fenghua Zhang
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, 050200, Hebei, China
| | - Jianping Zhang
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, 050200, Hebei, China.,Hebei key laboratory of integrative Medicine on Liver-Kidney Patterns, Shijiazhuang, 050200, Hebei, China
| | - Li Chu
- Hebei University of Chinese Medicine, No. 3, Xingyuan Road, Shijiazhuang, 050200, Hebei, China.,Hebei key laboratory of integrative Medicine on Liver-Kidney Patterns, Shijiazhuang, 050200, Hebei, China
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16
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Huang H, Pugsley MK, Fermini B, Curtis MJ, Koerner J, Accardi M, Authier S. Cardiac voltage-gated ion channels in safety pharmacology: Review of the landscape leading to the CiPA initiative. J Pharmacol Toxicol Methods 2017; 87:11-23. [PMID: 28408211 DOI: 10.1016/j.vascn.2017.04.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 03/27/2017] [Accepted: 04/06/2017] [Indexed: 12/15/2022]
Abstract
Voltage gated ion channels are central in defining the fundamental properties of the ventricular cardiac action potential (AP), and are also involved in the development of drug-induced arrhythmias. Many drugs can inhibit cardiac ion currents, including the Na+ current (INa), L-type Ca2+ current (Ica-L), and K+ currents (Ito, IK1, IKs, and IKr), and thereby affect AP properties in a manner that can trigger or sustain cardiac arrhythmias. Since publication of ICH E14 and S7B over a decade ago, there has been a focus on drug effects on QT prolongation clinically, and on the rapidly activating delayed rectifier current (IKr), nonclinically, for evaluation of proarrhythmic risk. This focus on QT interval prolongation and a single ionic current likely impacted negatively some drugs that lack proarrhythmic liability in humans. To rectify this issue, the Comprehensive in vitro proarrhythmia assay (CiPA) initiative has been proposed to integrate drug effects on multiple cardiac ionic currents with in silico modelling of human ventricular action potentials, and in vitro data obtained from human stem cell-derived ventricular cardiomyocytes to estimate proarrhythmic risk of new drugs with improved accuracy. In this review, we present the physiological functions and the molecular basis of major cardiac ion channels that contribute to the ventricle AP, and discuss the CiPA paradigm in drug development.
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Affiliation(s)
- Hai Huang
- CiToxLAB North America, 445, Armand-Frappier Boul, Laval H7V 4B3, QC, Canada
| | - Michael K Pugsley
- Department of Toxicology, Purdue Pharma L.P., Cranbury, NJ 08512, USA
| | | | - Michael J Curtis
- Cardiovascular Division, Faculty of Life Sciences & Medicine, King's College London, Rayne Institute, St Thomas' Hospital, London SE17EH, UK
| | - John Koerner
- Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Michael Accardi
- CiToxLAB North America, 445, Armand-Frappier Boul, Laval H7V 4B3, QC, Canada
| | - Simon Authier
- CiToxLAB North America, 445, Armand-Frappier Boul, Laval H7V 4B3, QC, Canada.
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17
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Bohnen MS, Peng G, Robey SH, Terrenoire C, Iyer V, Sampson KJ, Kass RS. Molecular Pathophysiology of Congenital Long QT Syndrome. Physiol Rev 2017; 97:89-134. [PMID: 27807201 PMCID: PMC5539372 DOI: 10.1152/physrev.00008.2016] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Ion channels represent the molecular entities that give rise to the cardiac action potential, the fundamental cellular electrical event in the heart. The concerted function of these channels leads to normal cyclical excitation and resultant contraction of cardiac muscle. Research into cardiac ion channel regulation and mutations that underlie disease pathogenesis has greatly enhanced our knowledge of the causes and clinical management of cardiac arrhythmia. Here we review the molecular determinants, pathogenesis, and pharmacology of congenital Long QT Syndrome. We examine mechanisms of dysfunction associated with three critical cardiac currents that comprise the majority of congenital Long QT Syndrome cases: 1) IKs, the slow delayed rectifier current; 2) IKr, the rapid delayed rectifier current; and 3) INa, the voltage-dependent sodium current. Less common subtypes of congenital Long QT Syndrome affect other cardiac ionic currents that contribute to the dynamic nature of cardiac electrophysiology. Through the study of mutations that cause congenital Long QT Syndrome, the scientific community has advanced understanding of ion channel structure-function relationships, physiology, and pharmacological response to clinically employed and experimental pharmacological agents. Our understanding of congenital Long QT Syndrome continues to evolve rapidly and with great benefits: genotype-driven clinical management of the disease has improved patient care as precision medicine becomes even more a reality.
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Affiliation(s)
- M S Bohnen
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - G Peng
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - S H Robey
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - C Terrenoire
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - V Iyer
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - K J Sampson
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - R S Kass
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
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18
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Hazell L, Raschi E, Ponti F, Thomas SHL, Salvo F, Ahlberg Helgee E, Boyer S, Sturkenboom M, Shakir S. Evidence for the hERG Liability of Antihistamines, Antipsychotics, and Anti‐Infective Agents: A Systematic Literature Review From the ARITMO Project. J Clin Pharmacol 2016; 57:558-572. [DOI: 10.1002/jcph.838] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 10/08/2016] [Indexed: 01/28/2023]
Affiliation(s)
- Lorna Hazell
- Drug Safety Research Unit Southampton United Kingdom
| | - Emanuel Raschi
- Department of Medical and Surgical SciencesUniversity of Bologna Bologna Italy
| | - Fabrizio Ponti
- Department of Medical and Surgical SciencesUniversity of Bologna Bologna Italy
| | - Simon H. L. Thomas
- Institute of Cellular MedicineFaculty of MedicineNewcastle University Newcastle United Kingdom
| | | | - Ernst Ahlberg Helgee
- Drug Safety and MetabolismAstraZeneca Innovative Medicines and Early Development Mölndal Sweden
| | - Scott Boyer
- Computational Toxicology, Swedish Toxicology Sciences Research Center Södertälje Sweden
| | | | - Saad Shakir
- Drug Safety Research Unit Southampton United Kingdom
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19
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Wiśniowska B, Polak S. The Role of Interaction Model in Simulation of Drug Interactions and QT Prolongation. CURRENT PHARMACOLOGY REPORTS 2016; 2:339-344. [PMID: 27917367 PMCID: PMC5114317 DOI: 10.1007/s40495-016-0075-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Computational modelling is a cornerstone of Comprehensive In Vitro Proarrhythmia Assay and is re-increasingly being used in drug development. Electrophysiological effects of drug-drug interactions can be predicted in silico, e.g. with the use of in vitro cardiac ion channel data, PK profiles and human ventricular cardiomyocyte models. There are, however, several approaches with different assumptions used to assess the combined effect of multiple drugs, and there is no agreed standard interaction model. The aim of this study was to assess whether the choice of the drug-drug interaction (DDI) model (Bliss independence, Loewe additivity, or simple sum) influences the results of QT interval simulation trial. The Simcyp Simulator version 12.1 (Simcyp Ltd. [part of Certara], Sheffield, UK) and Cardiac Safety Simulator 2.0 (Simcyp Ltd. [part of Certara], Sheffield, UK) were used to simulate results of 8 virtual trials mimicking clinical studies and generate individual QTc data. The combined effect of inhibitory actions of drugs which were given simultaneously was calculated with use of three different interaction models. The PD effect of DDI was assessed and the differences between mean observed and mean predicted ΔQTcB values for terfenadine interactions were not statistically significant in all but one cases. Differences between the three DDI models are not statistically significant, implying that the choice of the DDI model, in the case of lack of synergy or antagonism, is irrelevant to the average predicted effect at the clinical level. However, in some cases, it can influence the verdict on combinatorial therapy safety for individual patients.
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Affiliation(s)
- Barbara Wiśniowska
- Unit of Pharmacoepidemiology and Pharmacoeconomics, Faculty of Pharmacy, Medical College, Jagiellonian University, Medyczna 9 Street, 30-688 Kraków, Poland
| | - Sebastian Polak
- Unit of Pharmacoepidemiology and Pharmacoeconomics, Faculty of Pharmacy, Medical College, Jagiellonian University, Medyczna 9 Street, 30-688 Kraków, Poland
- Simcyp (part of Certara), Blades Enterprise Centre John Street, Sheffield, S2 4SU UK
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20
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Cubeddu LX. Drug-induced Inhibition and Trafficking Disruption of ion Channels: Pathogenesis of QT Abnormalities and Drug-induced Fatal Arrhythmias. Curr Cardiol Rev 2016; 12:141-54. [PMID: 26926294 PMCID: PMC4861943 DOI: 10.2174/1573403x12666160301120217] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 02/29/2016] [Indexed: 01/11/2023] Open
Abstract
Risk of severe and fatal ventricular arrhythmias, presenting as Torsade de Pointes (TdP), is increased in congenital and acquired forms of long QT syndromes (LQTS). Drug-induced inhibition of K+ currents, IKs, IKr, IK1, and/or Ito, delay repolarization, prolong QT, and increase the risk of TdP. Drug-induced interference with IKr is the most common cause of acquired LQTS/TdP. Multiple drugs bind to KNCH2-hERG-K+ channels affecting IKr, including antiarrythmics, antibiotics, antivirals, azole-antifungals, antimalarials, anticancer, antiemetics, prokinetics, antipsychotics, and antidepressants. Azithromycin has been recently added to this list. In addition to direct channel inhibition, some drugs interfere with the traffic of channels from the endoplasmic reticulum to the cell membrane, decreasing mature channel membrane density; e.g., pentamidine, geldalamicin, arsenic trioxide, digoxin, and probucol. Other drugs, such as ketoconazole, fluoxetine, norfluoxetine, citalopram, escitalopram, donepezil, tamoxifen, endoxifen, atazanavir, and roxitromycin, induce both direct channel inhibition and impaired channel trafficking. Although many drugs prolong the QT interval, TdP is a rare event. The following conditions increase the risk of drug-induced TdP: a) Disease states/electrolyte levels (heart failure, structural cardiac disease, bradycardia, hypokalemia); b) Pharmacogenomic variables (presence of congenital LQTS, subclinical ion-channel mutations, history of or having a relative with history of drug-induced long QT/TdP); c) Pharmacodynamic and kinetic factors (high doses, women, elderly, metabolism inhibitors, combining two or more QT prolonging drugs, drugs that prolong the QT and increase QT dispersion, and drugs with multiple actions on ion channels). Because most of these conditions are preventable, careful evaluation of risk factors and increased knowledge of drug use associated with repolarization abnormalities are strongly recommended.
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Affiliation(s)
- Luigi X Cubeddu
- Division of Cardio-Metabolic Research, Department of Pharmaceutical Sciences, Health professions Division, Nova Southeastern University, 3200 S. University Dr., Davie, FL, 333218, USA.
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21
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Han SN, Jing Y, Yang LL, Zhang Z, Zhang LR. Propofol inhibits hERG K + channels and enhances the inhibition effects on its mutations in HEK293 cells. Eur J Pharmacol 2016; 791:168-178. [PMID: 27575519 DOI: 10.1016/j.ejphar.2016.08.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 08/12/2016] [Accepted: 08/25/2016] [Indexed: 12/19/2022]
Abstract
QT interval prolongation, a potential risk for arrhythmias, may result from gene polymorphisms relevant to cardiomyocyte repolarization. Another noted cause of QT interval prolongation is the administration of chemical compounds such as anesthetics, which may affect a specific type of cardiac K+ channel encoded by the human ether-a-go-go-related gene (hERG). hERG K+ current was recorded using whole-cell patch clamp in human embryonic kidney (HEK293) cells expressing wild type (WT) or mutated hERG channels. Expression of hERG K+ channel proteins was evaluated using western blot and confirmed by fluorescent staining and imaging. Computational modeling was adopted to identify the possible binding site(s) of propofol with hERG K+ channels. Propofol had a significant inhibitory effect on WT hERG K+ currents in a concentration-dependent manner, with a half-maximal inhibitory concentration (IC50) of 60.9±6.4μM. Mutations in drug-binding sites (Y652A or F656C) of the hERG channel were found to attenuate hERG current blockage by propofol. However, propofol did not inhibit the trafficking of hERG protein to the cell membrane. Meanwhile, for the three selective hERG K+ channel mutant heterozygotes WT/Q738X-hERG, WT/A422T-hERG, and WT/H562P-hERG, the IC50 of propofol was calculated as 14.2±2.8μM, 3.3±1.2μM, and 5.9±1.9μM, respectively, which were much lower than that for the wild type. These findings indicate that propofol may potentially increase QT interval prolongation risk in patients via direct inhibition of the hERG K+ channel, especially in those with other concurrent triggering factors such as hERG gene mutations.
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Affiliation(s)
- Sheng-Na Han
- Department of Pharmacology, Basic Medical College, Zhengzhou University, Zhengzhou 450001, China
| | - Ying Jing
- Department of Physiology and Neurobiology, Basic Medical College, Zhengzhou University, Zhengzhou 450001, China
| | - Lin-Lin Yang
- Department of Pharmacology, Basic Medical College, Zhengzhou University, Zhengzhou 450001, China; Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Zhao Zhang
- Jiangsu Key Laboratory for Molecular & Medical Biotechnology, College of Life Science in Nanjing Normal University, Nanjing 210046, China.
| | - Li-Rong Zhang
- Department of Pharmacology, Basic Medical College, Zhengzhou University, Zhengzhou 450001, China.
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22
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Evaluation of nefazodone-induced cardiotoxicity in human induced pluripotent stem cell-derived cardiomyocytes. Toxicol Appl Pharmacol 2016; 296:42-53. [DOI: 10.1016/j.taap.2016.01.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 01/12/2016] [Accepted: 01/21/2016] [Indexed: 01/10/2023]
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23
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Foo B, Williamson B, Young JC, Lukacs G, Shrier A. hERG quality control and the long QT syndrome. J Physiol 2016; 594:2469-81. [PMID: 26718903 DOI: 10.1113/jp270531] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 12/07/2015] [Indexed: 11/08/2022] Open
Abstract
Long-QT syndrome type-2 (LQT2) is characterized by reduced functional expression of the human ether-à-go-go related (hERG) gene product, resulting in impaired cardiac repolarization and predisposition to fatal arrhythmia. Previous studies have implicated abnormal trafficking of misfolded hERG as the primary mechanism of LQT2, with misfolding being caused by mutations in the hERG gene (inherited) or drug treatment (acquired). More generally, environmental and metabolic stresses present a constant challenge to the folding of proteins, including hERG, and must be countered by robust protein quality control (QC) systems. Disposal of partially unfolded yet functional plasma membrane (PM) proteins by protein QC contributes to the loss-of-function phenotype in various conformational diseases including cystic fibrosis (CF) and long-QT syndrome type-2 (LQT2). The prevalent view has been that the loss of PM expression of hERG is attributed to biosynthetic block by endoplasmic reticulum (ER) QC pathways. However, there is a growing appreciation for protein QC pathways acting at post-ER cellular compartments, which may contribute to conformational disease pathogenesis. This article will provide a background on the structure and cellular trafficking of hERG as well as inherited and acquired LQT2. We will review previous work on hERG ER QC and introduce the more novel view that there is a significant peripheral QC at the PM and peripheral cellular compartments. Particular attention is drawn to the unique role of the peripheral QC system in acquired LQT2. Understanding the QC process and players may provide targets for therapeutic intervention in dealing with LQT2.
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Affiliation(s)
- Brian Foo
- Department of Physiology, McGill University, Montréal, Québec, Canada, H3G 1Y6
| | - Brittany Williamson
- Department of Biochemistry, McGill University, Montréal, Québec, Canada, H3G 1Y6
| | - Jason C Young
- Department of Biochemistry, McGill University, Montréal, Québec, Canada, H3G 1Y6
| | - Gergely Lukacs
- Department of Physiology, McGill University, Montréal, Québec, Canada, H3G 1Y6
| | - Alvin Shrier
- Department of Physiology, McGill University, Montréal, Québec, Canada, H3G 1Y6
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24
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De Martin M, Toja PM, Goulene K, Radaelli P, Cavagnini F, Stramba-Badiale M, Pecori Giraldi F. No Untoward Effect of Long-Term Ketoconazole Administration on Electrocardiographic QT Interval in Patients with Cushing's Disease. Basic Clin Pharmacol Toxicol 2015; 118:279-83. [PMID: 26386326 DOI: 10.1111/bcpt.12490] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 09/01/2015] [Indexed: 02/04/2023]
Abstract
Ketoconazole is listed among drugs that prolong QT interval and may increase the risk of torsade de pointes, a severe ventricular arrhythmia. This compound has recently been approved for treatment of Cushing's syndrome, a severe endocrine disorder. These patients harbour several risk factors for prolonged QT interval, for example hypokalaemia and left ventricular hypertrophy, but no study has evaluated whether administration of ketoconazole affects their QT interval. The aim of this study was to assess the QT interval in patients with Cushing's disease during long-term administration of ketoconazole. Electrocardiograms from 15 patients with Cushing's disease (12 women, 3 men, age: 37.8 ± 2.66 years) on ketoconazole treatment (100 mg-800 mg qd) for 1 month to 12 years were reviewed retrospectively. QT interval was measured and corrected for heart rate (QTc). Measurements before and during ketoconazole treatment were compared and any abnormal QTc value recorded. Concurrent medical therapies were also documented. On average, QTc was superimposable before and during ketoconazole treatment (393.2 ± 7.17 versus 403.3 ± 6.05 msec. in women; 424.3 ± 23.54 versus 398.0 ± 14.93 msec. in men, N.S.). QTc normalized on ketoconazole in one man with prolonged QTc prior to treatment; no abnormal QTc was observed in any other patient during the entire observation period, even during concurrent treatment with other QT-prolonging drugs. In conclusion, long-term ketoconazole administration does not appear to be associated with significant prolongation of QT interval in patients with Cushing's disease. ECG monitoring can follow recommendations drawn for other low-risk QT-prolonging drugs with attention to specific risk factors, for example hypokalaemia and drug interactions.
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Affiliation(s)
- Martina De Martin
- Neuroendocrinology Research Laboratory, IRCCS Istituto Auxologico Italiano, Milan, Italy
| | - Paola Maria Toja
- Division of Endocrinology and Metabolic Diseases, IRCCS Istituto Auxologico Italiano, Milan, Italy
| | - Karine Goulene
- Department of Geriatrics and Cardiovascular Medicine, IRCCS Istituto Auxologico Italiano, Milan, Italy
| | - Piero Radaelli
- Neuroendocrinology Research Laboratory, IRCCS Istituto Auxologico Italiano, Milan, Italy
| | - Francesco Cavagnini
- Neuroendocrinology Research Laboratory, IRCCS Istituto Auxologico Italiano, Milan, Italy
| | - Marco Stramba-Badiale
- Department of Geriatrics and Cardiovascular Medicine, IRCCS Istituto Auxologico Italiano, Milan, Italy
| | - Francesca Pecori Giraldi
- Neuroendocrinology Research Laboratory, IRCCS Istituto Auxologico Italiano, Milan, Italy.,Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
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Nogawa H, Kawai T. hERG trafficking inhibition in drug-induced lethal cardiac arrhythmia. Eur J Pharmacol 2014; 741:336-9. [DOI: 10.1016/j.ejphar.2014.06.044] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 06/16/2014] [Accepted: 06/23/2014] [Indexed: 02/01/2023]
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Mitcheson J, Arcangeli A. The Therapeutic Potential of hERG1 K+ Channels for Treating Cancer and Cardiac Arrhythmias. ION CHANNEL DRUG DISCOVERY 2014. [DOI: 10.1039/9781849735087-00258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
hERG potassium channels present pharmacologists and medicinal chemists with a dilemma. On the one hand hERG is a major reason for drugs being withdrawn from the market because of drug induced long QT syndrome and the associated risk of inducing sudden cardiac death, and yet hERG blockers are still widely used in the clinic to treat cardiac arrhythmias. Moreover, in the last decade overwhelming evidence has been provided that hERG channels are aberrantly expressed in cancer cells and that they contribute to tumour cell proliferation, resistance to apoptosis, and neoangiogenesis. Here we provide an overview of the properties of hERG channels and their role in excitable cells of the heart and nervous system as well as in cancer. We consider the therapeutic potential of hERG, not only with regard to the negative impact due to drug induced long QT syndrome, but also its future potential as a treatment in the fight against cancer.
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Affiliation(s)
- John Mitcheson
- University of Leicester, Department of Cell Physiology and Pharmacology, Medical Sciences Building University Road Leicester LE1 9HN UK
| | - Annarosa Arcangeli
- Department of Experimental Pathology and Oncology, University of Florence Viale GB Morgagni, 50 50134 Firenze Italy
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Varkevisser R, Houtman MJC, Linder T, de Git KCG, Beekman HDM, Tidwell RR, Ijzerman AP, Stary-Weinzinger A, Vos MA, van der Heyden MAG. Structure-activity relationships of pentamidine-affected ion channel trafficking and dofetilide mediated rescue. Br J Pharmacol 2014; 169:1322-34. [PMID: 23586323 DOI: 10.1111/bph.12208] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 02/13/2013] [Accepted: 04/04/2013] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Drug interference with normal hERG protein trafficking substantially reduces the channel density in the plasma membrane and thereby poses an arrhythmic threat. The chemical substructures important for hERG trafficking inhibition were investigated using pentamidine as a model drug. Furthermore, the relationship between acute ion channel block and correction of trafficking by dofetilide was studied. EXPERIMENTAL APPROACH hERG and K(IR)2.1 trafficking in HEK293 cells was evaluated by Western blot and immunofluorescence microscopy after treatment with pentamidine and six pentamidine analogues, and correction with dofetilide and four dofetilide analogues that displayed different abilities to inhibit IKr . Molecular dynamics simulations were used to address mode, number and type of interactions between hERG and dofetilide analogues. KEY RESULTS Structural modifications of pentamidine differentially affected plasma membrane levels of hERG and K(IR)2.1. Modification of the phenyl ring or substituents directly attached to it had the largest effect, affirming the importance of these chemical residues in ion channel binding. PA-4 had the mildest effects on both ion channels. Dofetilide corrected pentamidine-induced hERG, but not K(IR)2.1 trafficking defects. Dofetilide analogues that displayed high channel affinity, mediated by pi-pi stacks and hydrophobic interactions, also restored hERG protein levels, whereas analogues with low affinity were ineffective. CONCLUSIONS AND IMPLICATIONS Drug-induced trafficking defects can be minimized if certain chemical features are avoided or 'synthesized out'; this could influence the design and development of future drugs. Further analysis of such features in hERG trafficking correctors may facilitate the design of a non-blocking corrector for trafficking defective hERG proteins in both congenital and acquired LQTS.
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Affiliation(s)
- R Varkevisser
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
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HAN SHENGNA, YANG SONGHUA, ZHANG YU, SUN XIAOYAN, DUAN YANYAN, HU XIANGJIE, FAN TIANLI, HUANG CHENZHENG, YANG GE, ZHANG ZHAO, ZHANG LIRONG. Identification and functional characterization of the human ether-a-go-go-related gene Q738X mutant associated with hereditary long QT syndrome type 2. Int J Mol Med 2014; 34:810-5. [DOI: 10.3892/ijmm.2014.1827] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 06/23/2014] [Indexed: 11/06/2022] Open
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Han SN, Yang SH, Zhang Y, Duan YY, Sun XY, Chen Q, Fan TL, Ye ZK, Huang CZ, Hu XJ, Zhang Z, Zhang LR. Blockage of hERG current and the disruption of trafficking as induced by roxithromycin. Can J Physiol Pharmacol 2013; 91:1112-8. [DOI: 10.1139/cjpp-2012-0456] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Roxithromycin is an oral macrolide antibiotic agent that has been repeatedly reported to provoke excessive prolongation of the Q–T interval and torsades de pointes in clinical settings. To investigate the mechanisms underlying the arrhythmogenic side effects of roxithromycin, we studied the molecular mechanisms of roxithromycin on human ether-à-go-go-related gene (hERG) K+ channels expressed in human embryonic kidney (HEK293) cells. Roxithromycin was found to inhibit wild-type (WT) hERG currents in a concentration-dependent manner with a half-maximum block concentration (IC50) of 55.8 ± 9.1 μmol/L. S6 residue hERG mutants (Y652A and F656C) showed reduced levels of hERG current blockage attributable to roxithromycin. Roxithromycin also inhibited the trafficking of hERG protein to the cell membrane, as confirmed by Western blot analysis and confocal microscopy. These findings indicate that roxithromycin may cause acquired long-QT syndrome via direct inhibition of hERG current and by disruption of hERG protein trafficking. Mutations in drug-binding sites (Y652A or F656C) of the hERG channel were found to attenuate hERG current blockage by roxithromycin, but did not significantly alter the disruption of trafficking.
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Affiliation(s)
- Sheng-Na Han
- Department of Pharmacology, School of Medicine, Zhengzhou University, Zhengzhou, China
| | - Song-Hua Yang
- The First Affiliated Hospital, Zhengzhou University, Zhengzhou, China
| | - Yu Zhang
- Pharmacy College of Zhengzhou Railway Vocational, Zhengzhou, China
| | - Yan-Yan Duan
- Department of Pharmacology, School of Medicine, Zhengzhou University, Zhengzhou, China
| | - Xiao-Yan Sun
- Department of Pharmacology, School of Medicine, Zhengzhou University, Zhengzhou, China
| | - Qiu Chen
- Department of Pharmacology, School of Medicine, Zhengzhou University, Zhengzhou, China
| | - Tian-Li Fan
- Department of Pharmacology, School of Medicine, Zhengzhou University, Zhengzhou, China
| | - Zhen-Kun Ye
- Department of Pharmacology, School of Medicine, Zhengzhou University, Zhengzhou, China
| | - Chen-Zheng Huang
- Department of Pharmacology, School of Medicine, Zhengzhou University, Zhengzhou, China
| | - Xiang-Jie Hu
- Department of Pharmacology, School of Medicine, Zhengzhou University, Zhengzhou, China
| | - Zhao Zhang
- Jiangsu the Key Laboratory for Molecular and Medical Biotechnology, College of Life Science in Nanjing Normal University, Nanjing, China
| | - Li-Rong Zhang
- Department of Pharmacology, School of Medicine, Zhengzhou University, Zhengzhou, China
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Apaja PM, Foo B, Okiyoneda T, Valinsky WC, Barriere H, Atanasiu R, Ficker E, Lukacs GL, Shrier A. Ubiquitination-dependent quality control of hERG K+ channel with acquired and inherited conformational defect at the plasma membrane. Mol Biol Cell 2013; 24:3787-804. [PMID: 24152733 PMCID: PMC3861077 DOI: 10.1091/mbc.e13-07-0417] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Membrane trafficking in concert with the peripheral quality control machinery plays a critical role in preserving plasma membrane (PM) protein homeostasis. Unfortunately, the peripheral quality control may also dispose of partially or transiently unfolded polypeptides and thereby contribute to the loss-of-expression phenotype of conformational diseases. Defective functional PM expression of the human ether-a-go-go-related gene (hERG) K(+) channel leads to the prolongation of the ventricular action potential that causes long QT syndrome 2 (LQT2), with increased propensity for arrhythmia and sudden cardiac arrest. LQT2 syndrome is attributed to channel biosynthetic processing defects due to mutation, drug-induced misfolding, or direct channel blockade. Here we provide evidence that a peripheral quality control mechanism can contribute to development of the LQT2 syndrome. We show that PM hERG structural and metabolic stability is compromised by the reduction of extracellular or intracellular K(+) concentration. Cardiac glycoside-induced intracellular K(+) depletion conformationally impairs the complex-glycosylated channel, which provokes chaperone- and C-terminal Hsp70-interacting protein-dependent polyubiquitination, accelerated internalization, and endosomal sorting complex required for transport-dependent lysosomal degradation. A similar mechanism contributes to the down-regulation of PM hERG harboring LQT2 missense mutations, with incomplete secretion defect. These results suggest that PM quality control plays a determining role in the loss-of-expression phenotype of hERG in certain hereditary and acquired LTQ2 syndromes.
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Affiliation(s)
- Pirjo M Apaja
- Department of Physiology and Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, QC H3E 1Y6, Canada
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DI Veroli GY, Davies MR, Zhang H, Abi-Gerges N, Boyett MR. hERG inhibitors with similar potency but different binding kinetics do not pose the same proarrhythmic risk: implications for drug safety assessment. J Cardiovasc Electrophysiol 2013; 25:197-207. [PMID: 24118558 DOI: 10.1111/jce.12289] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 08/22/2013] [Accepted: 08/29/2013] [Indexed: 02/02/2023]
Abstract
INTRODUCTION Since the discovery of the link that exists between drug-induced hERG inhibition and Torsade de Pointes (TdP), extreme attention has been given to avoid new drugs inhibiting this channel. hERG inhibition is routinely screened for in new drugs and, typically, IC50 values are compared to projected plasma concentrations to define a safety margin. METHODS AND RESULTS We aimed to show that drugs with similar hERG potency are not uniformly pro-arrhythmic-this depends on the drug binding kinetics and mode of action (trapped or not) rather than the IC50 value only. We used a mathematical model of hERG and its related encoded current IKr to simulate drug binding in different configurations. Expression systems mimicking the screening process were first investigated. hERG model was then incorporated into a canine action potential (AP) and tissue model to study the impact of drug binding configurations on AP and pseudo-ECG (QT interval prolongation). Our data show that: (1) trapped and not trapped configurations and different binding kinetics could be identified during hERG screening; (2) slow binding, not trapped drugs, induced less AP prolongation and minimal QT interval prolongation (4.7%) at a concentration equal to the IC50 whereas maximal pro-arrhythmic risk was observed for trapped drugs at the same concentration (QT interval prolongation, 23.1%). CONCLUSION Our study demonstrates the need for screening for hERG binding configurations rather than potency alone. It also demonstrates the potential link between hERG, drug mode of action and TdP, and the need to question the current regulatory guidance.
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Affiliation(s)
- Giovanni Y DI Veroli
- Institute of Cardiovascular Sciences, University of Manchester, Manchester, UK; Translational Safety, Drug Safety & Metabolism, AstraZeneca, Manchester, UK
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Jehle J, Ficker E, Wan X, Deschenes I, Kisselbach J, Wiedmann F, Staudacher I, Schmidt C, Schweizer PA, Becker R, Katus HA, Thomas D. Mechanisms of zolpidem-induced long QT syndrome: acute inhibition of recombinant hERG K(+) channels and action potential prolongation in human cardiomyocytes derived from induced pluripotent stem cells. Br J Pharmacol 2013; 168:1215-29. [PMID: 23061993 DOI: 10.1111/bph.12002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 09/09/2012] [Accepted: 09/23/2012] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE Zolpidem, a short-acting hypnotic drug prescribed to treat insomnia, has been clinically associated with acquired long QT syndrome (LQTS) and torsade de pointes (TdP) tachyarrhythmia. LQTS is primarily attributed to reduction of cardiac human ether-a-go-go-related gene (hERG)/I(Kr) currents. We hypothesized that zolpidem prolongs the cardiac action potential through inhibition of hERG K(+) channels. EXPERIMENTAL APPROACH Two-electrode voltage clamp and whole-cell patch clamp electrophysiology was used to record hERG currents from Xenopus oocytes and from HEK 293 cells. In addition, hERG protein trafficking was evaluated in HEK 293 cells by Western blot analysis, and action potential duration (APD) was assessed in human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes. KEY RESULTS Zolpidem caused acute hERG channel blockade in oocytes (IC(50) = 61.5 μM) and in HEK 293 cells (IC(50) = 65.5 μM). Mutation of residues Y652 and F656 attenuated hERG inhibition, suggesting drug binding to a receptor site inside the channel pore. Channels were blocked in open and inactivated states in a voltage- and frequency-independent manner. Zolpidem accelerated hERG channel inactivation but did not affect I-V relationships of steady-state activation and inactivation. In contrast to the majority of hERG inhibitors, hERG cell surface trafficking was not impaired by zolpidem. Finally, acute zolpidem exposure resulted in APD prolongation in hiPSC-derived cardiomyocytes. CONCLUSIONS AND IMPLICATIONS Zolpidem inhibits cardiac hERG K(+) channels. Despite a relatively low affinity of zolpidem to hERG channels, APD prolongation may lead to acquired LQTS and TdP in cases of reduced repolarization reserve or zolpidem overdose.
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Affiliation(s)
- J Jehle
- Department of Cardiology, Medical University Hospital, Heidelberg, Heidelberg, Germany
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34
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Cardiac ion channel trafficking defects and drugs. Pharmacol Ther 2013; 139:24-31. [DOI: 10.1016/j.pharmthera.2013.03.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 03/14/2013] [Indexed: 01/19/2023]
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Rampe D, Brown AM. A history of the role of the hERG channel in cardiac risk assessment. J Pharmacol Toxicol Methods 2013; 68:13-22. [DOI: 10.1016/j.vascn.2013.03.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 03/14/2013] [Accepted: 03/14/2013] [Indexed: 01/25/2023]
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Inside job: ligand-receptor pharmacology beneath the plasma membrane. Acta Pharmacol Sin 2013; 34:859-69. [PMID: 23685953 PMCID: PMC3703709 DOI: 10.1038/aps.2013.51] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 04/07/2013] [Indexed: 12/24/2022] Open
Abstract
Most drugs acting on the cell surface receptors are membrane permeable and thus able to engage their target proteins in different subcellular compartments. However, these drugs' effects on cell surface receptors have historically been studied on the plasma membrane alone. Increasing evidence suggests that small molecules may also modulate their targeted receptors through membrane trafficking or organelle-localized signaling inside the cell. These additional modes of interaction have been reported for functionally diverse ligands of GPCRs, ion channels, and transporters. Such intracellular drug-target engagements affect cell surface expression. Concurrent intracellular and cell surface signaling may also increase the complexity and therapeutic opportunities of small molecule modulation. Here we discuss examples of ligand-receptor interactions that are present in both intra- and extracellular sites, and the potential therapeutic opportunities presented by this phenomenon.
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Azzam R, Shaikh AG, Serra A, Katirji B. Exacerbation of myasthenia gravis with voriconazole. Muscle Nerve 2013; 47:928-30. [PMID: 23666793 DOI: 10.1002/mus.23751] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/10/2012] [Indexed: 11/11/2022]
Abstract
INTRODUCTION We describe a patient with stable generalized myasthenia gravis who presented with new onset severe ophthalmoplegia and ptosis after initiation of voriconazole for aspergillosis. METHODS Ligand-protein docking software was used to simulate the interaction of voriconazole with the acetylcholine receptor (AChR). We tested voriconazole binding to AChR in comparison to high affinity and neutral compounds. RESULTS There was no clinical improvement after intravenous immunoglobulin infusion and plasmapheresis. However, the patient improved slowly after withdrawal of voriconazole. Based on our results, voriconazole binds favorably to AChR and may putatively block muscle nicotinic AChRs. Other theoretical explanations include blocking potassium channels and reducing their intracellular trafficking. CONCLUSIONS The mechanisms involved in ocular exacerbation may be multi-factorial, reflecting the intricate dynamics of the neuromuscular junction. It is important to consider medications that harbor pyridine or pyrimidine moieties as potential causes of exacerbation in myasthenic patients, especially those who present with ocular symptoms.
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Affiliation(s)
- Raed Azzam
- Neuromuscular Center, Department of Neurology and Neurological Institute, University Hospitals Case Medical Center, 11100 Euclid Avenue, Cleveland, Ohio 44106-5098, USA
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Liu Q, Mao X, Zeng F, Jin S, Yang X. Effect of daurisoline on HERG channel electrophysiological function and protein expression. JOURNAL OF NATURAL PRODUCTS 2012; 75:1539-1545. [PMID: 22974355 DOI: 10.1021/np300232b] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Daurisoline (1) is a bis-benzylisoquinoline alkaloid isolated from the rhizomes of Menispermum dauricum. The antiarrhythmic effect of 1 has been demonstrated in different experimental animals. In previous studies, daurisoline (1) prolonged action potential duration (APD) in a normal use-dependent manner. However, the electrophysiological mechanisms for 1-induced prolongation of APD have not been documented. In the present study, the direct effect of 1 was investigated on the hERG current and the expression of mRNA and protein in human embryonic kidney 293 (HEK293) cells stably expressing the hERG channel. It was shown that 1 inhibits hERG current in a concentration- and voltage-dependent manner. In the presence of 10 μM 1, steady-state inactivation of V(1/2) was shifted negatively by 15.9 mV, and 1 accelerated the onset of inactivation. Blockade of hERG channels was dependent on channel opening. The expression and function of hERG were unchanged by 1 at 1 and 10 μM, while hERG expression and the hERG current were decreased significantly by 1 at 30 μM. These results indicate that 1, at concentrations below 30 μM, exerts a blocking effect on hERG, but does not affect the expression and function of the hERG channel. This may explain the relatively lower risk of long QT syndrome after long-term usage.
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Affiliation(s)
- Qiangni Liu
- Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology , The Key Laboratory of Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, Wuhan, Hubei, 430030, People's Republic of China
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Vandenberg JI, Perry MD, Perrin MJ, Mann SA, Ke Y, Hill AP. hERG K+ Channels: Structure, Function, and Clinical Significance. Physiol Rev 2012; 92:1393-478. [DOI: 10.1152/physrev.00036.2011] [Citation(s) in RCA: 463] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The human ether-a-go-go related gene (hERG) encodes the pore-forming subunit of the rapid component of the delayed rectifier K+ channel, Kv11.1, which are expressed in the heart, various brain regions, smooth muscle cells, endocrine cells, and a wide range of tumor cell lines. However, it is the role that Kv11.1 channels play in the heart that has been best characterized, for two main reasons. First, it is the gene product involved in chromosome 7-associated long QT syndrome (LQTS), an inherited disorder associated with a markedly increased risk of ventricular arrhythmias and sudden cardiac death. Second, blockade of Kv11.1, by a wide range of prescription medications, causes drug-induced QT prolongation with an increase in risk of sudden cardiac arrest. In the first part of this review, the properties of Kv11.1 channels, including biogenesis, trafficking, gating, and pharmacology are discussed, while the second part focuses on the pathophysiology of Kv11.1 channels.
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Affiliation(s)
- Jamie I. Vandenberg
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Matthew D. Perry
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Mark J. Perrin
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Stefan A. Mann
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Ying Ke
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Adam P. Hill
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
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Yun J, Bae H, Choi SE, Kim JH, Choi YW, Lim I, Lee CS, Lee MW, Ko JH, Seo SJ, Bang H. Hirsutenone directly blocks human ether-a-go-go related gene K+ channels. Biol Pharm Bull 2012; 34:1815-22. [PMID: 22130236 DOI: 10.1248/bpb.34.1815] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of the present study was to investigate whether hirsutenone affects the human ether-a-go-go related gene (hERG) K(+) channels. Many drugs promote formation of the acquired form of long QT syndrome (LQTS) by blocking the hERG K(+) channels. Hirsutenone, a new candidate for the treatment inflammatory skin lesions, induced a concentration-dependent decrease in hERG K(+) current amplitudes. Hirsutenone significantly decreased the time constants at the onset of inactivation. However, the reductions in the time constants of steady-state inactivation and the recovery from inactivation after hirsutenone treatment were not significant. In addition, the drug had no effect on the voltage-dependent activation curve or the steady-state inactivation curve. In summary, hirsutenone potentially acts as a blocker of hERG K(+) channels functioning by modifying the channel inactivation kinetics.
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Affiliation(s)
- Jihyun Yun
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul 156–756, Korea
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Dennis AT, Wang L, Wan H, Nassal D, Deschenes I, Ficker E. Molecular determinants of pentamidine-induced hERG trafficking inhibition. Mol Pharmacol 2011; 81:198-209. [PMID: 22046004 DOI: 10.1124/mol.111.075135] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Pentamidine is an antiprotozoal compound that clinically causes acquired long QT syndrome (acLQTS), which is associated with prolonged QT intervals, tachycardias, and sudden cardiac arrest. Pentamidine delays terminal repolarization in human heart by acutely blocking cardiac inward rectifier currents. At the same time, pentamidine reduces surface expression of the cardiac potassium channel I(Kr)/human ether à-go-go-related gene (hERG). This is unusual in that acLQTS is caused most often by direct block of the cardiac potassium current I(Kr)/hERG. The present study was designed to provide a more complete picture of how hERG surface expression is disrupted by pentamidine at the cellular and molecular levels. Using biochemical and electrophysiological methods, we found that pentamidine exclusively inhibits hERG export from the endoplasmic reticulum to the cell surface in a heterologous expression system as well as in cardiomyocytes. hERG trafficking inhibition could be rescued in the presence of the pharmacological chaperone astemizole. We used rescue experiments in combination with an extensive mutational analysis to locate an interaction site for pentamidine at phenylalanine 656, a crucial residue in the canonical drug binding site of terminally folded hERG. Our data suggest that pentamidine binding to a folding intermediate of hERG arrests channel maturation in a conformational state that cannot be exported from the endoplasmic reticulum. We propose that pentamidine is the founding member of a novel pharmacological entity whose members act as small molecule antichaperones.
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Affiliation(s)
- Adrienne T Dennis
- Rammelkamp Center for Education and Research, MetroHealth Campus, Cleveland, OH 44109, USA
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Dennis AT, Nassal D, Deschenes I, Thomas D, Ficker E. Antidepressant-induced ubiquitination and degradation of the cardiac potassium channel hERG. J Biol Chem 2011; 286:34413-25. [PMID: 21832094 PMCID: PMC3190784 DOI: 10.1074/jbc.m111.254367] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2011] [Revised: 07/30/2011] [Indexed: 11/06/2022] Open
Abstract
The most common cause for adverse cardiac events by antidepressants is acquired long QT syndrome (acLQTS), which produces electrocardiographic abnormalities that have been associated with syncope, torsade de pointes arrhythmias, and sudden cardiac death. acLQTS is often caused by direct block of the cardiac potassium current I(Kr)/hERG, which is crucial for terminal repolarization in human heart. Importantly, desipramine belongs to a group of tricyclic antidepressant compounds that can simultaneously block hERG and inhibit its surface expression. Although up to 40% of all hERG blockers exert combined hERG block and trafficking inhibition, few of these compounds have been fully characterized at the cellular level. Here, we have studied in detail how desipramine inhibits hERG surface expression. We find a previously unrecognized combination of two entirely different mechanisms; desipramine increases hERG endocytosis and degradation as a consequence of drug-induced channel ubiquitination and simultaneously inhibits hERG forward trafficking from the endoplasmic reticulum. This unique combination of cellular effects in conjunction with acute channel block may explain why tricyclic antidepressants as a compound class are notorious for their association with arrhythmias and sudden cardiac death. Taken together, we describe the first example of drug-induced channel ubiquitination and degradation. Our data are directly relevant to the cardiac safety of not only tricyclic antidepressants but also other therapeutic compounds that exert multiple effects on hERG, as hERG trafficking and degradation phenotypes may go undetected in most preclinical safety assays designed to screen for acLQTS.
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Affiliation(s)
- Adrienne T. Dennis
- From the Rammelkamp Center for Education and Research, MetroHealth Campus, Case Western Reserve University, Cleveland Ohio 44109
| | - Drew Nassal
- From the Rammelkamp Center for Education and Research, MetroHealth Campus, Case Western Reserve University, Cleveland Ohio 44109
- the Department of Physiology and Biophysics, Case Western Reserve University, Cleveland Ohio 44106, and
| | - Isabelle Deschenes
- From the Rammelkamp Center for Education and Research, MetroHealth Campus, Case Western Reserve University, Cleveland Ohio 44109
- the Department of Physiology and Biophysics, Case Western Reserve University, Cleveland Ohio 44106, and
| | - Dierk Thomas
- the Department of Cardiology, Medical University Hospital Heidelberg, D-69120 Heidelberg, Germany
| | - Eckhard Ficker
- From the Rammelkamp Center for Education and Research, MetroHealth Campus, Case Western Reserve University, Cleveland Ohio 44109
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Church MK. Safety and efficacy of bilastine: a new H(1)-antihistamine for the treatment of allergic rhinoconjunctivitis and urticaria. Expert Opin Drug Saf 2011; 10:779-93. [PMID: 21831011 DOI: 10.1517/14740338.2011.604029] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION New H(1)-antihistamines should be effective in relieving the symptoms of allergic disease, should have a rapid onset and long duration of action and should neither cause sedation nor interact with cytochrome P450. A review of bilastine was undertaken to determine whether this newer H(1)-antihistamine meets these requirements. AREAS COVERED A Medline search was conducted to identify preclinical and clinical studies of bilastine. This was supplemented with additional articles or abstracts cited in reference lists and/or obtained from online sources and internal reports supplied by Faes Farma. Review of these data indicated that bilastine has high selectivity for H(1)-receptors, is rapidly and effectively absorbed, undergoes negligible metabolism and is a substrate for P-glycoprotein, which limits its passage across the blood-brain barrier. At the recommended dose of 20 mg, bilastine is non-sedative, does not enhance the effects of alcohol or CNS sedatives, does not impair actual driving tests, shows no cardiotoxicity and has a similar efficacy to other second-generation H(1)-antihistamines in the treatment of allergic rhinoconjunctivitis and urticaria. EXPERT OPINION In view of its favorable pharmacological and clinical characteristics, bilastine is likely to have particular benefit in urticaria for which guidelines recommend increasing the dosage of H(1)-antihistamines up to fourfold if standard dosing is ineffective.
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Affiliation(s)
- Martin K Church
- Allergie-Centrum-Charité, Department of Dermatology and Allergy, Charité-Universitätsmedizin Berlin, Charitéplatz 1, D-10117, Berlin, Germany.
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Supplemental Studies for Cardiovascular Risk Assessment in Safety Pharmacology: A Critical Overview. Cardiovasc Toxicol 2011; 11:285-307. [DOI: 10.1007/s12012-011-9133-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Sissung TM, Gardner ER, Piekarz RL, Howden R, Chen X, Woo S, Franke R, Clark JA, Miller-DeGraff L, Steinberg SM, Venzon D, Liewehr D, Kleeberger SR, Bates SE, Price DK, Rosing DR, Cabell C, Sparreboom A, Figg WD. Impact of ABCB1 allelic variants on QTc interval prolongation. Clin Cancer Res 2011; 17:937-46. [PMID: 21106724 PMCID: PMC3074531 DOI: 10.1158/1078-0432.ccr-10-0925] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
PURPOSE Although the ABCB1 (P-glycoprotein) drug transporter is a constituent of several blood-tissue barriers (i.e., blood-brain and blood-nerve), its participation in a putative blood-heart barrier has been poorly explored. ABCB1 could decrease the intracardiac concentrations of drugs that cause QT prolongation and cardiotoxicity. EXPERIMENTAL DESIGN ABCB1-related romidepsin transport kinetics were explored in LLC-PK1 cells transfected with different ABCB1 genetic variants. ABCB1 plasma and intracardiac concentrations were determined in Abcb1a/1b (-/-) mice and wild-type FVB controls. These same mice were used to evaluate romidepsin-induced heart rate-corrected QT interval (QTc) prolongation over time. Finally, a cohort of 83 individuals with available QTcB and ABCB1 genotyping data were used to compare allelic variation in ABCB1 versus QTc-prolongation phenotype. RESULTS Here, we show that mice lacking the ABCB1-type P-glycoprotein have higher intracardiac concentrations of a model ABCB1 substrate, romidepsin, that correspond to changes in QT prolongation from baseline (ΔQTc) over time. Consistent with this observation, we also show that patients carrying genetic variants that could raise ABCB1 expression in the cardiac endothelium have lower ΔQTc following a single dose of romidepsin. CONCLUSIONS To our knowledge, this is the first evidence that Abcb1-type P-glycoprotein can limit intracardiac exposure to a drug that mediates QT prolongation and suggests that certain commonly inherited polymorphisms in ABCB1 may serve as markers for QT prolongation following the administration of ABCB1-substrate drugs.
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Affiliation(s)
- Tristan M. Sissung
- Clinical Pharmacology Program, Center for Cancer Research National Cancer Institute, Bethesda, MD
| | - Erin R. Gardner
- Clinical Pharmacology Program, SAIC-Frederick, NCI-Frederick, MD
| | - Richard L. Piekarz
- Medical Oncology Branch, Center for Cancer Research National Cancer Institute, Bethesda, MD
| | - Reuben Howden
- Laboratory of Respiratory Biology, National Institute of Environmental Health Science, Durham, NC
| | - Xaiohong Chen
- Clinical Pharmacology Program, Center for Cancer Research National Cancer Institute, Bethesda, MD
| | - Sukyung Woo
- Clinical Pharmacology Program, Center for Cancer Research National Cancer Institute, Bethesda, MD
| | - Ryan Franke
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, TN
| | - James A. Clark
- Laboratory of Respiratory Biology, National Institute of Environmental Health Science, Durham, NC
| | - Laura Miller-DeGraff
- Laboratory of Respiratory Biology, National Institute of Environmental Health Science, Durham, NC
| | - Seth M. Steinberg
- Biostatistics and Data Management Section, National Cancer Institute, Bethesda, MD
| | - David Venzon
- Biostatistics and Data Management Section, National Cancer Institute, Bethesda, MD
| | - David Liewehr
- Biostatistics and Data Management Section, National Cancer Institute, Bethesda, MD
| | - Steven R. Kleeberger
- Laboratory of Respiratory Biology, National Institute of Environmental Health Science, Durham, NC
| | - Susan E. Bates
- Medical Oncology Branch, Center for Cancer Research National Cancer Institute, Bethesda, MD
| | - Douglas K. Price
- Molecular Pharmacology Section, Center for Cancer Research National Cancer Institute, Bethesda, MD
| | - Douglas R. Rosing
- Cardiovascular Branch, National Heart Lung and Blood Institute, Bethesda, MD
| | | | - Alex Sparreboom
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, TN
| | - William D. Figg
- Clinical Pharmacology Program, Center for Cancer Research National Cancer Institute, Bethesda, MD
- Medical Oncology Branch, Center for Cancer Research National Cancer Institute, Bethesda, MD
- Molecular Pharmacology Section, Center for Cancer Research National Cancer Institute, Bethesda, MD
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Staudacher I, Wang L, Wan X, Obers S, Wenzel W, Tristram F, Koschny R, Staudacher K, Kisselbach J, Koelsch P, Schweizer PA, Katus HA, Ficker E, Thomas D. hERG K+ channel-associated cardiac effects of the antidepressant drug desipramine. Naunyn Schmiedebergs Arch Pharmacol 2010; 383:119-39. [DOI: 10.1007/s00210-010-0583-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 11/19/2010] [Indexed: 01/31/2023]
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Fluconazole inhibits hERG K(+) channel by direct block and disruption of protein trafficking. Eur J Pharmacol 2010; 650:138-44. [PMID: 20951697 DOI: 10.1016/j.ejphar.2010.10.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 09/15/2010] [Accepted: 10/03/2010] [Indexed: 11/21/2022]
Abstract
Fluconazole, a commonly used azole antifungal drug, can induce QT prolongation, which may lead to Torsades de Pointes and sudden death. To investigate the arrhythmogenic side effects of fluconazole, we studied the effect of fluconazole on human ether-a-go-go-related gene (hERG) K(+) channels (wild type, Y652A and F656C) expressed in human embryonic kidney (HEK293) cells using a whole-cell patch clamp technique, Western blot analysis and confocal microscopy. Fluconazole inhibited wild type hERG currents in a concentration-dependent manner, with a half-maximum block concentration (IC(50)) of 48.2±9.4μM. Fluconazole did not change other channel kinetics (activation and steady-state inactivation) of hERG channel. Mutations in drug- binding sites (Y652A or F656C) of the hERG channel significantly attenuated the hERG current blockade by fluconazole. In addition, fluconazole inhibited the trafficking of hERG protein by Western blot analysis and confocal microscopy, respectively. These findings indicate that fluconazole may cause acquired long QT syndrome (LQTS) via a direct inhibition of hERG current and by disrupting hERG protein trafficking, and the mutations Y652 and F656 may be obligatory determinants in inhibition of hERG current for fluconazole.
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Smyth JW, Shaw RM. Forward trafficking of ion channels: what the clinician needs to know. Heart Rhythm 2010; 7:1135-40. [PMID: 20621620 DOI: 10.1016/j.hrthm.2010.05.030] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Accepted: 05/20/2010] [Indexed: 11/25/2022]
Abstract
Each heartbeat requires precisely orchestrated action potential propagation through the myocardium, achieved by coordination of about a million ion channels on the surface of each cardiomyocyte. Specific ion channels must occur within discrete subdomains of the sarcolemma to exert their electrophysiological effects with highest efficiency (e.g., voltage-gated Ca(2+) channels at T-tubules and gap junctions at intercalated discs). Regulation of ion channel movement to their appropriate membrane subdomain is an exciting research frontier with opportunity for novel therapeutic manipulation of ion channels in the treatment of heart disease. Although much research has generally focused on internalization and subsequent degradation of ion channels, the field of forward trafficking of de novo ion channels from the cell interior to the sarcolemma has now emerged as a key regulatory step in cardiac electrophysiological function. In this brief review, we provide an overview of the current understanding of the cellular biology governing the forward trafficking of ion channels.
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Affiliation(s)
- James W Smyth
- Cardiovascular Research Institute and Department of Medicine, University of California San Francisco, San Francisco, California, USA.
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