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Hadova K, Kmecova J, Ochodnicka‐Mackovicova K, Kralova E, Doka G, Bies Pivackova L, Vavrinec P, Stankovicova T, Krenek P, Klimas J. Rapid changes of mRNA expressions of cardiac ion channels affected by Torsadogenic drugs influence susceptibility of rat hearts to arrhythmias induced by Beta-Adrenergic stimulation. Pharmacol Res Perspect 2023; 11:e01134. [PMID: 37715323 PMCID: PMC10504435 DOI: 10.1002/prp2.1134] [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: 07/20/2023] [Revised: 08/16/2023] [Accepted: 08/17/2023] [Indexed: 09/17/2023] Open
Abstract
Drug-induced long QT syndrome (LQTS) and Torsades de Pointes (TdP) are serious concerns in drug development. Although rats are a useful scientific tool, their hearts, unlike larger species, usually do not respond to torsadogenic drugs. Consequently, their resistance to drug-induced arrhythmias is poorly understood. Here, we challenged rats with rapid delayed rectifier current (Ikr)-inhibiting antibiotic clarithromycin (CLA), loop diuretic furosemide (FUR) or their combination (CLA + FUR), and examined functional and molecular abnormalities after stimulation with isoproterenol. Clarithromycin and furosemide were administered orally at 12-h intervals for 7 days. To evaluate electrical instability, electrocardiography (ECG) was recorded either in vivo or ex vivo using the Langendorff-perfused heart method under basal conditions and subsequently under beta-adrenergic stimulation. Gene expression was measured using real-time quantitative PCR in left ventricular tissue. Indeed, FUR and CLA + FUR rats exhibited hypokalemia. CLA and CLA + FUR treatment resulted in drug-induced LQTS and even an episode of TdP in one CLA + FUR rat. The combined treatment dysregulated gene expression of several ion channels subunits, including KCNQ1, calcium channels and Na+/K + -ATPase subunits, while both monotherapies had no impact. The rat with recorded TdP exhibited differences in the expression of ion channel genes compared to the rest of rats within the CLA + FUR group. The ECG changes were not detected in isolated perfused hearts. Hence, we report rapid orchestration of ion channel reprogramming of hearts with QT prolongation induced by simultaneous administration of clarithromycin and furosemide in rats, which may account for their ability to avoid arrhythmias triggered by beta-adrenergic stimulation.
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Affiliation(s)
- Katarina Hadova
- Department of Pharmacology and Toxicology, Faculty of PharmacyComenius University BratislavaBratislavaSlovakia
| | - Jana Kmecova
- Department of Pharmacology and Toxicology, Faculty of PharmacyComenius University BratislavaBratislavaSlovakia
- State Institute for Drug ControlBratislavaSlovakia
| | | | - Eva Kralova
- Department of Pharmacology and Toxicology, Faculty of PharmacyComenius University BratislavaBratislavaSlovakia
| | - Gabriel Doka
- Department of Pharmacology and Toxicology, Faculty of PharmacyComenius University BratislavaBratislavaSlovakia
| | - Lenka Bies Pivackova
- Department of Pharmacology and Toxicology, Faculty of PharmacyComenius University BratislavaBratislavaSlovakia
| | - Peter Vavrinec
- Department of Pharmacology and Toxicology, Faculty of PharmacyComenius University BratislavaBratislavaSlovakia
| | - Tatiana Stankovicova
- Department of Pharmacology and Toxicology, Faculty of PharmacyComenius University BratislavaBratislavaSlovakia
| | - Peter Krenek
- Department of Pharmacology and Toxicology, Faculty of PharmacyComenius University BratislavaBratislavaSlovakia
| | - Jan Klimas
- Department of Pharmacology and Toxicology, Faculty of PharmacyComenius University BratislavaBratislavaSlovakia
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Mason JM, O’Brien ME, Koehl JL, Ji CS, Hayes BD. Cardiovascular Pharmacology. Emerg Med Clin North Am 2022; 40:771-792. [DOI: 10.1016/j.emc.2022.06.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Ranolazine: An Old Drug with Emerging Potential; Lessons from Pre-Clinical and Clinical Investigations for Possible Repositioning. Pharmaceuticals (Basel) 2021; 15:ph15010031. [PMID: 35056088 PMCID: PMC8777683 DOI: 10.3390/ph15010031] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 12/16/2021] [Accepted: 12/20/2021] [Indexed: 02/07/2023] Open
Abstract
Ischemic heart disease is a significant public health problem with high mortality and morbidity. Extensive scientific investigations from basic sciences to clinics revealed multilevel alterations from metabolic imbalance, altered electrophysiology, and defective Ca2+/Na+ homeostasis leading to lethal arrhythmias. Despite the recent identification of numerous molecular targets with potential therapeutic interest, a pragmatic observation on the current pharmacological R&D output confirms the lack of new therapeutic offers to patients. By contrast, from recent trials, molecules initially developed for other fields of application have shown cardiovascular benefits, as illustrated with some anti-diabetic agents, regardless of the presence or absence of diabetes, emphasizing the clear advantage of “old” drug repositioning. Ranolazine is approved as an antianginal agent and has a favorable overall safety profile. This drug, developed initially as a metabolic modulator, was also identified as an inhibitor of the cardiac late Na+ current, although it also blocks other ionic currents, including the hERG/Ikr K+ current. The latter actions have been involved in this drug’s antiarrhythmic effects, both on supraventricular and ventricular arrhythmias (VA). However, despite initial enthusiasm and promising development in the cardiovascular field, ranolazine is only authorized as a second-line treatment in patients with chronic angina pectoris, notwithstanding its antiarrhythmic properties. A plausible reason for this is the apparent difficulty in linking the clinical benefits to the multiple molecular actions of this drug. Here, we review ranolazine’s experimental and clinical knowledge on cardiac metabolism and arrhythmias. We also highlight advances in understanding novel effects on neurons, the vascular system, skeletal muscles, blood sugar control, and cancer, which may open the way to reposition this “old” drug alone or in combination with other medications.
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Bazoukis G, Tse G, Letsas KP, Thomopoulos C, Naka KK, Korantzopoulos P, Bazoukis X, Michelongona P, Papadatos SS, Vlachos K, Liu T, Efremidis M, Baranchuk A, Stavrakis S, Tsioufis C. Impact of ranolazine on ventricular arrhythmias - A systematic review. J Arrhythm 2018; 34:124-128. [PMID: 29657587 PMCID: PMC5891418 DOI: 10.1002/joa3.12031] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 11/29/2017] [Indexed: 12/15/2022] Open
Abstract
Ranolazine is a new medication for the treatment of refractory angina. However, except its anti-anginal properties, it has been found to act as an anti-arrhythmic. The aim of our systematic review is to present the existing data about the impact of ranolazine in ventricular arrhythmias. We searched MEDLINE and Cochrane databases as well clinicaltrials.gov until September 1, 2017 to find all studies (clinical trials, observational studies, case reports/series) reported data about the impact of ranolazine in ventricular arrhythmias. Our search revealed 14 studies (3 clinical trials, 2 observational studies, 8 case reports, 1 case series). These data reported a beneficial impact of ranolazine in ventricular tachycardia/fibrillation, premature ventricular beats, and ICD interventions in different clinical settings. The existing data highlight the anti-arrhythmic properties of ranolazine in ventricular arrhythmias.
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Affiliation(s)
- George Bazoukis
- Department of Cardiology Catheterization Laboratory Evangelismos General Hospital of Athens Athens Greece
| | - Gary Tse
- Department of Medicine and Therapeutics Faculty of Medicine Chinese University of Hong Kong Hong Kong China.,Li Ka Shing Institute of Health Sciences Faculty of Medicine Chinese University of Hong Kong Hong Kong China
| | - Konstantinos P Letsas
- Department of Cardiology Catheterization Laboratory Evangelismos General Hospital of Athens Athens Greece
| | | | - Katerina K Naka
- Second Department of Cardiology School of Medicine University of Ioannina Ioannina Greece
| | | | - Xenophon Bazoukis
- Department of Cardiology General Hospital of Ioannina, "G Hatzikosta" Ioannina Greece
| | - Paschalia Michelongona
- Department of Cardiology Catheterization Laboratory Evangelismos General Hospital of Athens Athens Greece
| | - Stamatis S Papadatos
- Faculty Department of Internal Medicine Athens School of Medicine Sotiria General Hospital National and Kapodistrian University of Athens Athens Greece
| | - Konstantinos Vlachos
- Department of Cardiology Catheterization Laboratory Evangelismos General Hospital of Athens Athens Greece
| | - Tong Liu
- Department of Cardiology Tianjin Institute of Cardiology Second Hospital of Tianjin Medical University Tianjin China
| | - Michael Efremidis
- Department of Cardiology Catheterization Laboratory Evangelismos General Hospital of Athens Athens Greece
| | - Adrian Baranchuk
- Division of Cardiology, Electrophysiology and Pacing Kingston General Hospital Queen's University Kingston ON Canada
| | - Stavros Stavrakis
- University of Oklahoma Health Sciences Center Oklahoma City Oklahoma
| | - Costas Tsioufis
- First Cardiology Clinic Hippokration Hospital University of Athens Athens Greece
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5
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Pre- and Delayed Treatments With Ranolazine Ameliorate Ventricular Arrhythmias and Nav1.5 Downregulation in Ischemic/Reperfused Rat Hearts. J Cardiovasc Pharmacol 2016; 68:269-279. [DOI: 10.1097/fjc.0000000000000412] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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6
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Morissette P, Regan C, Fitzgerald K, Gerenser P, Travis J, Wang S, Fanelli P, Sannajust F. Shortening of the electromechanical window in the ketamine/xylazine-anesthetized guinea pig model to assess pro-arrhythmic risk in early drug development. J Pharmacol Toxicol Methods 2016; 81:171-82. [DOI: 10.1016/j.vascn.2016.06.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 05/23/2016] [Accepted: 06/04/2016] [Indexed: 11/26/2022]
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7
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Chiba T, Kondo N, Takahara A. Influences of rapid pacing-induced electrical remodeling on pharmacological manipulation of the atrial refractoriness in rabbits. J Pharmacol Sci 2016; 130:170-6. [DOI: 10.1016/j.jphs.2016.02.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 01/28/2016] [Accepted: 02/21/2016] [Indexed: 01/10/2023] Open
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8
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Thomas SHL, Behr ER. Pharmacological treatment of acquired QT prolongation and torsades de pointes. Br J Clin Pharmacol 2015; 81:420-7. [PMID: 26183037 DOI: 10.1111/bcp.12726] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 07/13/2015] [Accepted: 07/14/2015] [Indexed: 12/21/2022] Open
Abstract
Torsades de pointes (TdP) is a characteristic polymorphic ventricular arrhythmia associated with delayed ventricular repolarization as evidenced on the surface electrocardiogram by QT interval prolongation. It typically occurs in self-limiting bursts, causing dizziness and syncope, but may occasionally progress to ventricular fibrillation and sudden death. Acquired long QT syndromes are mainly caused by cardiac disease, electrolyte abnormalities or exposure to drugs that block rectifying potassium channels, especially IKr. Management of TdP or marked QT prolongation includes removal or correction of precipitants, including discontinuation of culprit drugs and institution of cardiac monitoring. Electrolyte abnormalities and hypoxia should be corrected, with potassium concentrations maintained in the high normal range. Immediate treatment of TdP is by intravenous administration of magnesium sulphate, terminating prolonged episodes using electrical cardioversion. In refractory cases of recurrent TdP, the arrhythmia can be suppressed by increasing the underlying heart rate using isoproterenol (isoprenaline) or transvenous pacing. Other interventions are rarely needed, but there are case reports of successful use of lidocaine or phenytoin. Anti-arrhythmic drugs that prolong ventricular repolarization should be avoided. Some episodes of TdP could be avoided by careful prescribing of QT prolonging drugs, including an individualized assessment of risks and benefits before use, performing baseline and periodic electrocardiograms and measurement of electrolytes, especially during acute illnesses, using the lowest effective dose for the shortest possible time and avoiding potential drug interactions. These steps are particularly important in those with underlying repolarization abnormalities and those who have previously experienced drug-induced TdP.
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Affiliation(s)
- Simon H L Thomas
- Medical Toxicology Centre, Wolfson Building, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE2 4HH.,National Poisons Information Service Newcastle Unit, Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE1 4LP
| | - Elijah R Behr
- Cardiovascular Research Centre, St George's University of London, London, SW17 0RE, UK
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Gupta T, Khera S, Kolte D, Aronow WS, Iwai S. Antiarrhythmic properties of ranolazine: A review of the current evidence. Int J Cardiol 2015; 187:66-74. [PMID: 25828315 DOI: 10.1016/j.ijcard.2015.03.324] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 03/20/2015] [Indexed: 12/19/2022]
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10
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Sossalla S, Wallisch N, Toischer K, Sohns C, Vollmann D, Seegers J, Lüthje L, Maier LS, Zabel M. Effects of ranolazine on torsades de pointes tachycardias in a healthy isolated rabbit heart model. Cardiovasc Ther 2015; 32:170-7. [PMID: 24785406 PMCID: PMC4285941 DOI: 10.1111/1755-5922.12078] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
PURPOSE Torsades de pointes (TdP) tachycardias are triggered, polymorphic ventricular arrhythmias arising from early afterdepolarizations (EADs) and increased dispersion of repolarization. Ranolazine is a new agent which reduces pathologically elevated late INa but also IKr . Aim of this study was to evaluate the effects of ranolazine in a validated isolated Langendorff-perfused rabbit heart model. METHODS TdP was reproducibly induced with d-sotalol (10(-4) mol/L) and low potassium (K) (1.0 mmol/L for 5 min, pacing at CL 1000 ms). In 10 hearts, ECG and 8 epi- and endocardial monophasic action potentials were recorded. Action potential duration (APD) was measured at 90% repolarization and dispersion defined as APD max-min. RESULTS D-sotalol prolonged APD90 and increased dispersion of APD90 , simultaneously causing EADs and induction of TdP. The combination of d-sotalol and two concentrations of ranolazine did not increase dispersion of ventricular APD90 as compared to vehicle. Ranolazine at 5 μmol/L did not cause additional induction of EADs and/or TdP but also did not significantly suppress arrhythmogenic triggers. The higher concentration of ranolazine (10 μmol/L) in combination with d-sotalol caused further prolongation of APD90 , at the same time reduction in APD90 dispersion. In parallel, the incidence of EADs was reduced and an antitorsadogenic effect was seen. CONCLUSIONS In the healthy isolated rabbit heart (where late INa is not elevated), ranolazine does not cause proarrhythmia but exerts antiarrhythmic effects in a dose-dependent manner against d-sotalol/low K-induced TdP. This finding-despite additional APD prolongation-supports the safety of a combined use of both drugs and merits clinical investigation.
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Affiliation(s)
- Samuel Sossalla
- Klinik für Kardiologie und Pneumologie/Herzzentrum, Georg-August-Universität Göttingen, Göttingen, Germany; DZHK (German Center for Cardiovascular Research), Göttingen, Germany
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11
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Assessment of anti-arrhythmic activity of antipsychotic drugs in an animal model: Influence of non-cardiac α1-adrenergic receptors. Eur J Pharmacol 2015; 748:10-7. [DOI: 10.1016/j.ejphar.2014.12.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 11/28/2014] [Accepted: 12/10/2014] [Indexed: 01/09/2023]
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12
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Varkevisser R, van der Heyden MAG, Tieland RG, Beekman JDM, Vos MA. Vernakalant is devoid of proarrhythmic effects in the complete AV block dog model. Eur J Pharmacol 2013; 720:49-54. [PMID: 24211677 DOI: 10.1016/j.ejphar.2013.10.054] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 10/25/2013] [Accepted: 10/29/2013] [Indexed: 11/28/2022]
Abstract
The anesthetized chronic AV-blocked dog (cAVB) and methoxamine-sensitized rabbit model are widely used to determine pro-arrhythmic properties of drugs. In general, both models show similar results. However, conflicting data have also been reported; K201 and AZD1305 induced Torsade de Pointes (TdP) exclusively in cAVB dogs. Vernakalant, an antiarrhythmic drug that blocks several ion channels has been approved only in Europe. Its propensity to induce repolarization-dependent TdP arrhythmias has been evaluated solely in the methoxamine-sensitized rabbits. We therefore assessed the proarrhythmic potential of vernakalant in the cAVB dog model. Vernakalant was evaluated in 10 mongrel dogs (sinus rhythm (SR) 2mg/kg; chronic AV block (cAVB) 2+3mg/kg). The same dogs were challenged with dofetilide (25 μg/kg) to evaluate TdP inducibility. During the serial experiments the animals were paced from the right ventricular apex (60 beats/min). Short-term variability of repolarization (STV) was quantified for proarrhythmic risk. In SR (n=8) vernakalant prolonged QT (265 ± 11 to 311 ± 18 ms P<0.01(**)) but not PQ or QRS. In cAVB (n=8), 2mg/kg vernakalant prolonged QT (391 ± 43 to 519 ± 73 ms(**)) and QRS (103 ± 24 to 108 ± 23 ms(**)). After a 30 min lag-time, 3mg/kg vernakalant (n=4) increased QT to a lesser extent (413 ± 34 to 454 ± 27 ms(**)) while maintaining QRS prolongation (114 ± 18 to 122 ± 20 ms(**)). Neither dose increased STV or caused arrhythmias. Dofetilide prolonged QT (398 ± 51 to 615 ± 71 ms(**)), increased STV (1.0 ± 0.4 to 2.2 ± 1.0 ms P<0.05(⁎)) and induced TdP arrhythmias in 6/8(⁎) cAVB dogs. Vernakalant did not induce arrhythmias in the cAVB dog model. Higher dosages (3mg/kg) did not prolong repolarization further whereas negative inotropic effects were starting to become apparent precluding further increases in dose.
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Affiliation(s)
- Rosanne Varkevisser
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
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13
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Verrier RL. Ranolazine's sweet side - improvement of glycaemic control by the novel mechanism of skeletal muscle microvascular recruitment. J Physiol 2013; 591:4961. [DOI: 10.1113/jphysiol.2013.260687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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14
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Khazraei H, Mirkhani H, Purkhosrow A. Vasorelaxant effect of ranolazine on isolated normal and diabetic rat aorta: A study of possible mechanisms. ACTA ACUST UNITED AC 2013; 100:153-62. [DOI: 10.1556/aphysiol.100.2013.2.3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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15
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Sicouri S, Belardinelli L, Antzelevitch C. Antiarrhythmic effects of the highly selective late sodium channel current blocker GS-458967. Heart Rhythm 2013; 10:1036-43. [PMID: 23524321 DOI: 10.1016/j.hrthm.2013.03.023] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Indexed: 12/14/2022]
Abstract
BACKGROUND Previous studies have shown that late sodium channel current (INa) blockers such as ranolazine can exert antiarrhythmic effects by suppressing early and delayed afterdepolarization (EAD and DAD)-induced triggered activity. OBJECTIVE To evaluate the electrophysiological properties of GS-458967 (GS967), a potent and highly selective late INa blocker, in canine Purkinje fibers (PFs) and pulmonary vein (PV) and superior vena cava (SVC) sleeve preparations. METHODS Transmembrane action potentials were recorded from canine PFs and PV and SVC sleeve preparations by using standard microelectrode techniques. The rapidly activating delayed rectifier potassium channel current blocker E-4031 (2.5-5 µM) and the late INa agonist ATX-II (10 nM) were used to induce EADs in PFs. Isoproterenol (1 µM), high calcium ([Ca(2+)]o = 5.4 mM), or their combination was used to induce DADs and triggered activity. RESULTS In PFs, GS967 (10-300 nM) caused a significant concentration-dependent reduction in action potential duration without altering the maximum rate of rise of the action potential upstroke, action potential amplitude, or resting membrane potential at any rate studied (basic cycle lengths of 1000, 500, and 300 ms) or concentration evaluated (n = 5; P < .05). GS967 (30-100 nM) abolished EADs and EAD-induced triggered activity elicited in PFs by exposure to E-4031 (n = 4) or ATX-II (n = 4). In addition, GS967 reduced or abolished DADs and suppressed DAD-induced triggered activity elicited in PFs (n = 4) and PV (n = 4) and SVC (n = 3) sleeve preparations by exposure to isoproterenol, high calcium, or their combination. CONCLUSIONS Our data suggest that the selective inhibition of late INa with GS967 can exert antiarrhythmic effects by suppressing EAD- and DAD-mediated extrasystolic activity in PFs and PV and SVC sleeve preparations.
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Affiliation(s)
- Serge Sicouri
- Masonic Medical Research Laboratory, Utica, New York 13501-1787, USA.
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16
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Abstract
Ranolazine is currently approved for use in chronic angina. The basis for this use is likely related to inhibition of late sodium channels with resultant beneficial downstream effects. Randomized clinical trials have demonstrated an improvement in exercise capacity and reduction in angina episodes with ranolazine. This therapeutic benefit occurs without the hemodynamic effects seen with the conventional antianginal agents. The inhibition of late sodium channels as well as other ion currents has a central role in the potential use of ranolazine in ischemic heart disease, arrhythmias, and heart failure. Despite its QTc-prolonging action, albeit minimal, clinical data have not shown a predisposition to torsades de pointes, and the medication has shown a reasonable safety profile even in those with structural heart disease. In this article we present the experimental and clinical data that support its current therapeutic role, and provide insight into potential future clinical applications.
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Affiliation(s)
- Nael Hawwa
- Internal Medicine Institute, Cleveland Clinic, Cleveland, OH 44195, USA
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18
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Belardinelli L, Liu G, Smith-Maxwell C, Wang WQ, El-Bizri N, Hirakawa R, Karpinski S, Hong Li C, Hu L, Li XJ, Crumb W, Wu L, Koltun D, Zablocki J, Yao L, Dhalla AK, Rajamani S, Shryock JC. A Novel, Potent, and Selective Inhibitor of Cardiac Late Sodium Current Suppresses Experimental Arrhythmias. J Pharmacol Exp Ther 2012; 344:23-32. [DOI: 10.1124/jpet.112.198887] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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19
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Negative electro-mechanical windows are required for drug-induced Torsades de Pointes in the anesthetized guinea pig. J Pharmacol Toxicol Methods 2012; 66:125-34. [DOI: 10.1016/j.vascn.2012.03.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 03/13/2012] [Accepted: 03/29/2012] [Indexed: 11/17/2022]
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Parikh A, Mantravadi R, Kozhevnikov D, Roche MA, Ye Y, Owen LJ, Puglisi JL, Abramson JJ, Salama G. Ranolazine stabilizes cardiac ryanodine receptors: a novel mechanism for the suppression of early afterdepolarization and torsades de pointes in long QT type 2. Heart Rhythm 2012; 9:953-60. [PMID: 22245792 DOI: 10.1016/j.hrthm.2012.01.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Indexed: 12/19/2022]
Abstract
BACKGROUND Ranolazine (Ran) is known to inhibit multiple targets, including the late Na(+)current, the rapid delayed rectifying K(+)current, the L-type Ca(2+)current, and fatty acid metabolism. Functionally, Ran suppresses early afterdepolarization (EADs) and torsades de pointes (TdP) in drug-induced long QT type 2 (LQT2) presumably by decreasing intracellular [Na(+)](i) and Ca(2+)overload. However, simulations of EADs in LQT2 failed to predict their suppression by Ran. OBJECTIVE To elucidate the mechanism(s) whereby Ran alters cardiac action potentials (APs) and cytosolic Ca(2+)transients and suppresses EADs and TdP in LQT2. METHODS The known effects of Ran were included in simulations (Shannon and Mahajan models) of rabbit ventricular APs and Ca(2+)transients in control and LQT2 models and compared with experimental optical mapping data from Langendorff rabbit hearts treated with E4031 (0.5 μM) to block the rapid delayed rectifying K(+)current. Direct effects of Ran on cardiac ryanodine receptors (RyR2) were investigated in single channels and changes in Ca(2+)-dependent high-affinity ryanodine binding. RESULTS Ran (10 μM) alone prolonged action potential durations (206 ± 4.6 to 240 ± 7.8 ms; P <0.05); E4031 prolonged action potential durations (204 ± 6 to 546 ± 35 ms; P <0.05) and elicited EADs and TdP that were suppressed by Ran (10 μM; n = 7 of 7 hearts). Simulations (Shannon but not Mahajan model) closely reproduced experimental data except for EAD suppression by Ran. Ran reduced open probability (P(o)) of RyR2 (half maximal inhibitory concentration = 10 ± 3 μM; n = 7) in bilayers and shifted half maximal effective concentration for Ca(2+)-dependent ryanodine binding from 0.42 ± 0.02 to 0.64 ± 0.02 μM with 30 μM Ran. CONCLUSIONS Ran reduces P(o) of RyR2, desensitizes Ca(2+)-dependent RyR2 activation, and inhibits Ca(i) oscillations, which represents a novel mechanism for its suppression of EADs and TdP.
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Affiliation(s)
- Ashish Parikh
- Department of Bioengineering, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA
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21
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Tamargo J, Caballero R, Delpón E. Ranolazine: an antianginal drug with antiarrhythmic properties. Expert Rev Cardiovasc Ther 2011; 9:815-27. [PMID: 21809962 DOI: 10.1586/erc.11.91] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Ranolazine is an agent approved for the symptomatic treatment of chronic stable angina that inhibits the late inward sodium current (I(NaL)). I(NaL) amplitude is increased under several pathological conditions, including increased oxidative stress, myocardial ischemia, cardiac hypertrophy, heart failure, long-QT syndrome variant 3 and atrial fibrillation. Experimental and preliminary clinical evidence suggests that ranolazine may represent a new therapeutic strategy in the treatment of a broad spectrum of cardiac arrhythmias. This article reviews the role of the I(NaL) and provides an update on experimental and clinical evidence supporting the efficacy and safety of ranolazine across a broad spectrum of arrhythmias.
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Affiliation(s)
- Juan Tamargo
- Department of Pharmacology, School of Medicine, Universidad Complutense, 28040 Madrid, Spain.
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Nieminen T, Tavares CA, Pegler JR, Belardinelli L, Verrier RL. Ranolazine Injection Into Coronary or Femoral Arteries Exerts Marked, Transient Regional Vasodilation Without Systemic Hypotension in an Intact Porcine Model. Circ Cardiovasc Interv 2011; 4:481-7. [DOI: 10.1161/circinterventions.111.962852] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Tuomo Nieminen
- From Beth Israel Deaconess Medical Center (T.N., C.A.M.T., J.R.M.P., R.L.V.) and Harvard Medical School (T.N., R.L.V.), Boston, MA; the Division of Cardiology, Helsinki University Central Hospital, Helsinki, Finland, and Department of Internal Medicine, Päijät-Häme Central Hospital, Lahti, Finland (T.N.); University of São Paulo School of Medicine, São Paulo, Brazil (C.A.M.T., J.R.M.P.); and Gilead Palo Alto, Inc, Foster City, CA (L.B.)
| | - Caio A.M. Tavares
- From Beth Israel Deaconess Medical Center (T.N., C.A.M.T., J.R.M.P., R.L.V.) and Harvard Medical School (T.N., R.L.V.), Boston, MA; the Division of Cardiology, Helsinki University Central Hospital, Helsinki, Finland, and Department of Internal Medicine, Päijät-Häme Central Hospital, Lahti, Finland (T.N.); University of São Paulo School of Medicine, São Paulo, Brazil (C.A.M.T., J.R.M.P.); and Gilead Palo Alto, Inc, Foster City, CA (L.B.)
| | - José R.M. Pegler
- From Beth Israel Deaconess Medical Center (T.N., C.A.M.T., J.R.M.P., R.L.V.) and Harvard Medical School (T.N., R.L.V.), Boston, MA; the Division of Cardiology, Helsinki University Central Hospital, Helsinki, Finland, and Department of Internal Medicine, Päijät-Häme Central Hospital, Lahti, Finland (T.N.); University of São Paulo School of Medicine, São Paulo, Brazil (C.A.M.T., J.R.M.P.); and Gilead Palo Alto, Inc, Foster City, CA (L.B.)
| | - Luiz Belardinelli
- From Beth Israel Deaconess Medical Center (T.N., C.A.M.T., J.R.M.P., R.L.V.) and Harvard Medical School (T.N., R.L.V.), Boston, MA; the Division of Cardiology, Helsinki University Central Hospital, Helsinki, Finland, and Department of Internal Medicine, Päijät-Häme Central Hospital, Lahti, Finland (T.N.); University of São Paulo School of Medicine, São Paulo, Brazil (C.A.M.T., J.R.M.P.); and Gilead Palo Alto, Inc, Foster City, CA (L.B.)
| | - Richard L. Verrier
- From Beth Israel Deaconess Medical Center (T.N., C.A.M.T., J.R.M.P., R.L.V.) and Harvard Medical School (T.N., R.L.V.), Boston, MA; the Division of Cardiology, Helsinki University Central Hospital, Helsinki, Finland, and Department of Internal Medicine, Päijät-Häme Central Hospital, Lahti, Finland (T.N.); University of São Paulo School of Medicine, São Paulo, Brazil (C.A.M.T., J.R.M.P.); and Gilead Palo Alto, Inc, Foster City, CA (L.B.)
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Antzelevitch C, Burashnikov A, Sicouri S, Belardinelli L. Electrophysiologic basis for the antiarrhythmic actions of ranolazine. Heart Rhythm 2011; 8:1281-90. [PMID: 21421082 DOI: 10.1016/j.hrthm.2011.03.045] [Citation(s) in RCA: 178] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 03/11/2011] [Indexed: 12/19/2022]
Abstract
Ranolazine is a Food and Drug Administration-approved antianginal agent. Experimental and clinical studies have shown that ranolazine has antiarrhythmic effects in both ventricles and atria. In the ventricles, ranolazine can suppress arrhythmias associated with acute coronary syndrome, long QT syndrome, heart failure, ischemia, and reperfusion. In atria, ranolazine effectively suppresses atrial tachyarrhythmias and atrial fibrillation (AF). Recent studies have shown that the drug may be effective and safe in suppressing AF when used as a pill-in-the pocket approach, even in patients with structurally compromised hearts, warranting further study. The principal mechanism underlying ranolazine's antiarrhythmic actions is thought to be primarily via inhibition of late I(Na) in the ventricles and via use-dependent inhibition of peak I(Na) and I(Kr) in the atria. Short- and long-term safety of ranolazine has been demonstrated in the clinic, even in patients with structural heart disease. This review summarizes the available data regarding the electrophysiologic actions and antiarrhythmic properties of ranolazine in preclinical and clinical studies.
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Thireau J, Pasquié JL, Martel E, Le Guennec JY, Richard S. New drugs vs. old concepts: a fresh look at antiarrhythmics. Pharmacol Ther 2011; 132:125-45. [PMID: 21420430 DOI: 10.1016/j.pharmthera.2011.03.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 03/01/2011] [Indexed: 01/10/2023]
Abstract
Common arrhythmias, particularly atrial fibrillation (AF) and ventricular tachycardia/fibrillation (VT/VF) are a major public health concern. Classic antiarrhythmic (AA) drugs for AF are of limited effectiveness, and pose the risk of life-threatening VT/VF. For VT/VF, implantable cardiac defibrillators appear to be the unique, yet unsatisfactory, solution. Very few AA drugs have been successful in the last few decades, due to safety concerns or limited benefits in comparison to existing therapy. The Vaughan-Williams classification (one drug for one molecular target) appears too restrictive in light of current knowledge of molecular and cellular mechanisms. New AA drugs such as atrial-specific and/or multichannel blockers, upstream therapy and anti-remodeling drugs, are emerging. We focus on the cellular mechanisms related to abnormal Na⁺ and Ca²⁺ handling in AF, heart failure, and inherited arrhythmias, and on novel strategies aimed at normalizing ionic homeostasis. Drugs that prevent excessive Na⁺ entry (ranolazine) and aberrant diastolic Ca²⁺ release via the ryanodine receptor RyR2 (rycals, dantrolene, and flecainide) exhibit very interesting antiarrhythmic properties. These drugs act by normalizing, rather than blocking, channel activity. Ranolazine preferentially blocks abnormal persistent (vs. normal peak) Na⁺ currents, with minimal effects on normal channel function (cell excitability, and conduction). A similar "normalization" concept also applies to RyR2 stabilizers, which only prevent aberrant opening and diastolic Ca²⁺ leakage in diseased tissues, with no effect on normal function during systole. The different mechanisms of action of AA drugs may increase the therapeutic options available for the safe treatment of arrhythmias in a wide variety of pathophysiological situations.
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Affiliation(s)
- Jérôme Thireau
- Inserm U1046 Physiologie & Médecine Expérimentale du Cœur et des Muscles, Université Montpellier-1, Université Montpellier-2, 34295 Montpellier Cedex 5, France
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Abstract
Chronic stable angina is an exceedingly prevalent condition with tremendous clinical, social, and financial implications. Traditional medical therapy for angina consists of beta-blockers, calcium channel blockers, and nitrates. These agents decrease myocardial oxygen demand and ischemia by reducing heart rate, lowering blood pressure, and/or optimizing ventricular loading characteristics. Unique in its mechanism of action, ranolazine is the first new antianginal agent approved for use in the US for chronic angina in over 25 years. By inhibiting the late inward sodium current (I(Na)), ranolazine prevents pathologic intracellular calcium accumulation that leads to ischemia, myocardial dysfunction, and electrical instability. Ranolazine has been proven in multiple clinical trials to reduce the symptoms of angina safely and effectively and to improve exercise tolerance in patients with symptomatic coronary heart disease. These benefits occur without reduction in heart rate and blood pressure or increased mortality. Although ranolazine prolongs the QT(c), experimental data indicate that ranolazine may actually be antiarrhythmic. In a large acute coronary syndrome clinical trial, ranolazine reduced the incidence of supraventricular tachycardia, ventricular tachycardia, new-onset atrial fibrillation, and bradycardic events. Additional benefits of ranolazine under investigation include reductions in glycosylated hemoglobin levels and improved left ventricular function. Ranolazine is a proven antianginal medication in patients with symptomatic coronary heart disease, and should be considered as an initial antianginal agent for those with hypotension or bradycardia.
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Affiliation(s)
- David S Vadnais
- Division of Cardiology, Emory University School of Medicine, Atlanta, Georgia, USA
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Jacobson I, Carlsson L, Duker G. Beat-by-beat QT interval variability, but not QT prolongation per se, predicts drug-induced torsades de pointes in the anaesthetised methoxamine-sensitized rabbit. J Pharmacol Toxicol Methods 2010; 63:40-6. [PMID: 20451633 DOI: 10.1016/j.vascn.2010.04.010] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 04/19/2010] [Accepted: 04/23/2010] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Accumulating evidence suggest that drug-induced QT prolongation per se poorly predicts repolarisation-related proarrhythmia liability. We examined whether beat-by-beat variability of the QT interval may be a complementary proarrhythmia marker to QT prolongation. METHODS Anaesthetised rabbits sensitized towards developing torsades de pointes (TdP) were infused for 30 min maximum with explorative antiarrhythmic compounds characterised as mixed ion channel blockers. Based on the outcome in this model the compounds were classified as having a low (TdPlow; n=5), intermediate (TdPintermediate; n=7) or high (TdPhigh; n=10) proarrhythmic potential. Dofetilide (n=4) was included as a representative of a selective IKr-blocking antiarrhythmic with known high proarrhythmic potential. QT interval prolongation and beat-by-beat QT variability (quantified as the short-term variability, STV) were continuously assessed during the infusion or up to the point where ventricular proarrhythmias were induced. RESULTS All compounds significantly prolonged the QT interval. For TdPlow and TdPhigh compounds the QT interval maximally increased from 169 ± 14 to 225 ± 28 ms (p<0.05) and from 186 ± 21 to 268 ± 42 ms (p<0.01), respectively. Likewise, in the dofetilide-infused rabbits the QT interval maximally increased from 177 ± 11 to 243 ± 25 ms (p<0.01). In contrast, whereas the STV in rabbits administered the TdPhigh compounds or dofetilide significantly increased prior to proarrhythmia induction (from 1.6 ± 0.4 to 10.5 ± 5.6 ms and from 1.6 ± 0.5 to 5.9 ± 1.8 ms, p<0.01) it remained unaltered in the TdPlow group (1.3 ± 0.6 to 2.2 ± 0.9 ms). In the TdPintermediate group, rabbits experiencing TdP had a similar maximal QT prolongation as the non-susceptible rabbits whereas the change in the STV was significantly different (from 0.9 ± 0.5 to 8.7 ± 7.3 ms vs 0.8 ± 0.3 to 2.5 ± 1.1 ms). DISCUSSION It is concluded from the present series of experiments in a sensitive rabbit model of TdP that increased beat-by-beat QT interval variability precedes drug-induced TdP. In addition, assessment of this potential proarrhythmia marker may be useful in discriminating highly proarrhythmic compounds from compounds with a low proarrhythmic potential.
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Antoons G, Oros A, Beekman JDM, Engelen MA, Houtman MJC, Belardinelli L, Stengl M, Vos MA. Late na(+) current inhibition by ranolazine reduces torsades de pointes in the chronic atrioventricular block dog model. J Am Coll Cardiol 2010; 55:801-9. [PMID: 20170820 DOI: 10.1016/j.jacc.2009.10.033] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 09/23/2009] [Accepted: 10/05/2009] [Indexed: 11/28/2022]
Abstract
OBJECTIVES This study investigated whether ranolazine reduces dofetilide-induced torsades de pointes (TdP) in a model of long QT syndrome with down-regulated K(+) currents due to hypertrophic remodeling in the dog with chronic atrioventricular block (cAVB). BACKGROUND Ranolazine inhibits the late Na(+) current (I(NaL)) and is effective against arrhythmias in long QT3 syndromes despite its blocking properties of the rapid component of delayed rectifying potassium current. METHODS Ranolazine was administered to cAVB dogs before or after TdP induction with dofetilide and electrophysiological parameters were determined including beat-to-beat variability of repolarization (BVR). In single ventricular myocytes, effects of ranolazine were studied on I(NaL), action potential duration, and dofetilide-induced BVR and early afterdepolarizations. RESULTS After dofetilide, ranolazine reduced the number of TdP episodes from 10 +/- 3 to 3 +/- 1 (p < 0.05) and partially reversed the increase of BVR with no abbreviation of the dofetilide-induced QT prolongation. Likewise, pre-treatment with ranolazine, or using lidocaine as a specific Na(+) channel blocker, attenuated TdP, but failed to prevent dofetilide-induced increases in QT, BVR, and ectopic activity. In cAVB myocytes, ranolazine suppressed dofetilide-induced early afterdepolarizations in 25% of cells at 5 micromol/l, in 75% at 10 micromol/l, and in 100% at 15 micromol/l. At 5 micromol/l, ranolazine blocked 26 +/- 3% of tetrodotoxin-sensitive I(NaL), and 49 +/- 3% at 15 micromol/l. Despite a 54% reduction of I(NaL) amplitude in cAVB compared with control cells, I(NaL) inhibition by 5 micromol/l tetrodotoxin equally shortened relative action potential duration and completely abolished dofetilide-induced early afterdepolarizations. CONCLUSIONS Despite down-regulation of I(NaL) in remodeled cAVB hearts, ranolazine is antiarrhythmic against drug-induced TdP. The antiarrhythmic effects are reflected in concomitant changes of BVR.
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Affiliation(s)
- Gudrun Antoons
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, University of Utrecht, Utrecht, the Netherlands
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A novel mechanism for the treatment of angina, arrhythmias, and diastolic dysfunction: inhibition of late I(Na) using ranolazine. J Cardiovasc Pharmacol 2010; 54:279-86. [PMID: 19333133 DOI: 10.1097/fjc.0b013e3181a1b9e7] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Inhibition of the persistent or late Na current (INa) using ranolazine (Ranexa) represents a novel mechanism of action that was approved in the United States in 2006 and only recently in the European Union for use in patients with stable angina pectoris. In general, myocardial ischemia is associated with reduced adenosine triphosphate fluxes and decreased energy supply, resulting in severe disturbances of intracellular ion homeostasis in cardiac myocytes. In the recent years, increased late INa was suggested to contribute to this phenomenon by elevating intracellular Na concentration with subsequent rise in diastolic Ca levels by means of the sarcolemmal Na-Ca exchange system. Ranolazine, a specific inhibitor of late INa, reduces Na influx and hence ameliorates disturbed Na and Ca homeostasis. This is associated with a symptomatic improvement of angina in patients unlike other antianginal drugs without affecting heart rate or systemic blood pressure as shown in placebo-controlled studies. Therefore, ranolazine is a useful new option for patients with chronic stable angina not only as an add-on therapy. New clinical and experimental studies even point to potential antiarrhythmic effects, beneficial effects in diastolic heart failure, and under hyperglycemic conditions. In the present article, the relevant pathophysiological concepts for the role of late INa inhibition are reviewed and the most recent data from basic studies and clinical trials are summarized.
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Andersson B, Abi-Gerges N, Carlsson L. The combined ion channel blocker AZD1305 attenuates late Na current and IKr-induced action potential prolongation and repolarization instability. Europace 2010; 12:1003-10. [DOI: 10.1093/europace/euq070] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Farkas AS, Nattel S. Minimizing Repolarization-Related Proarrhythmic Risk in Drug Development and Clinical Practice. Drugs 2010; 70:573-603. [DOI: 10.2165/11535230-000000000-00000] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Wu L, Rajamani S, Li H, January CT, Shryock JC, Belardinelli L. Reduction of repolarization reserve unmasks the proarrhythmic role of endogenous late Na(+) current in the heart. Am J Physiol Heart Circ Physiol 2009; 297:H1048-57. [PMID: 19592609 DOI: 10.1152/ajpheart.00467.2009] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Reduction of repolarization reserve increases the risk of arrhythmia. We hypothesized that inhibition of K(+) current (I(K)) to decrease repolarization reserve would unmask the proarrhythmic role of endogenous, physiological late Na(+) current (late I(Na)). Monophasic action potentials (MAP) and 12-lead electrocardiogram were recorded from female rabbit isolated hearts. To block I(K) and reduce repolarization reserve, E-4031, 4-aminopyridine, and BaCl(2) were used; to block endogenous late I(Na), tetrodotoxin (TTX) and ranolazine were used. E-4031 (1-60 nM) concentration-dependently prolonged MAP duration (MAPD(90)) and increased duration of the T wave from T(peak) to T(end) (T(peak)-T(end)), transmural dispersion of repolarization (TDR), and beat-to-beat variability (BVR) of MAPD(90). E-4031 caused spontaneous and pause-triggered polymorphic ventricular tachycardia [torsade de pointes (TdP)]. In the presence of 60 nM E-4031, TTX (0.6-3 muM) and ranolazine (5-10 muM) shortened MAPD(90), decreased TDR, BVR, and T(peak)-T(end) (n = 9-20, P < 0.01), and abolished episodes of TdP. In hearts treated with BaCl(2) or 4-aminopyridine plus E-4031, TTX (0.6-3 muM) shortened MAPD(90) and decreased T(peak)-T(end). Ranolazine could not reverse the effect of E-4031 to inhibit human ether-a-go-go-related gene (HERG) K(+) current; thus, the reversal by ranolazine of effects of E-4031 was likely due to inhibition of late I(Na) and not to antagonism of the HERG-blocking action of E-4031. We conclude that endogenous, physiological late I(Na) contributes to arrhythmogenesis in hearts with reduced repolarization reserve. Inhibition of this current partially reverses MAPD prolongation and abolishes arrhythmic activity caused by I(K) inhibitors.
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Affiliation(s)
- Lin Wu
- Pharmacological Sciences, Gilead Sciences, Palo Alto, California 94304, USA
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Assessment of the Ion Channel-blocking Profile of the Novel Combined Ion Channel Blocker AZD1305 and Its Proarrhythmic Potential Versus Dofetilide in the Methoxamine-sensitized Rabbit In Vivo. J Cardiovasc Pharmacol 2009; 54:82-9. [DOI: 10.1097/fjc.0b013e3181ac62c9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Wu J, Cheng L, Lammers WJ, Wu L, Wang X, Shryock JC, Belardinelli L, Lei M. Sinus node dysfunction in ATX-II-induced in-vitro murine model of long QT3 syndrome and rescue effect of ranolazine. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2009; 98:198-207. [PMID: 19351514 DOI: 10.1016/j.pbiomolbio.2009.01.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The aim of this study was to characterize the role of the late Na+ current (I(Na,L)) as a mechanism for induction of both tachy and bradyarrhythmias in murine heart and sino-atrial node tissue. The sea anemone toxin ATX-II and ranolazine were used to increase and inhibit, respectively, I(Na,L). In sixteen hearts studied, exposure to 1-10nM ATX-II caused a slowing of intrinsic heart rate and prolongations of the P-R and QT intervals, the duration of the monophasic action potential, and the sinus node recovery time, accompanied by frequent occurrences of early after depolarisations, delayed after depolarisations and rapid, repetitive ventricular tachy and sino-atrial bradyarrhythmias. ATX-II also slowed sinus node pacemaking, and induced bradycardic arrhythmias in isolated sino-atrial preparations (n=5). The ATX-II-induced alteration of electrophysiological properties and occurrence of arrhythmic events were significantly attenuated by 10 microM ranolazine in intact hearts (n=11) and isolated sino-atrial preparations (n=5). In conclusion, the I(Na,L) enhancer ATX-II causes both tachy and bradyarrhythmias in the murine heart, and these arrhythmias are markedly attenuated by the I(Na,L) blocker, ranolazine (10 microM). The results suggest that I(Na,L) blockade may be the mechanism underlying the reductions of both brady and tachyarrhythmias by ranolazine that were observed during the MERLIN-TIMI clinical outcomes trial.
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Affiliation(s)
- Jingjing Wu
- Centre for Ion Channel Research and Department of Cardiovascular Diseases, Xiehe Hospital, Huazhong University of Sciences and Technology, Wuhan, China
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