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Egorov YV. Atypical Antiadrenergic Effect of Refralon as a Mechanism of High Antiarrhythmic Effectiveness. Bull Exp Biol Med 2024:10.1007/s10517-024-06131-x. [PMID: 38954299 DOI: 10.1007/s10517-024-06131-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Indexed: 07/04/2024]
Abstract
We studied the effect of Refralon on the electrophysiological properties of the supraventricular myocardium against the background of adrenergic (epinephrine) influence in the zone of the pulmonary veins, the area where 50-90% of atrial arrhythmias is triggered. The experiments were carried out on isolated tissue preparations of Wistar rats. The multichannel microelectrode array technique was used to record action potentials simultaneously in the atrium and in the ostium and distal parts of the pulmonary veins. Epinephrine application (12-50 nM) led to depolarization of the resting potential and the conduction block in the distal part of the pulmonary veins. Refralon (30 μg/kg) restored the resting potential in the distal part of the pulmonary veins. Against the background of epinephrine, Refralon did not significantly change the duration of the action potential at 90% repolarization in comparison with control. At the same time, the comparison drug E-4031 against the background of epinephrine significantly increased the duration of action potential in the atrium and in the ostium of the pulmonary veins, and sotalol increased it only in the ostium. Neither E-4031, nor sotalol restored conduction in their distal part. Refralon has a biphasic effect under conditions of adrenergic stimulation: the fast component is responsible for stabilizing the resting potential in the pulmonary vein and reduces the dispersion of action potential duration in the atrium and pulmonary vein and is also quickly washed away, and the slow component is responsible for the increase of the action potential duration and is slowly washed away.
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Affiliation(s)
- Y V Egorov
- National Medical Research Centre of Cardiology named after academician E. I. Chazov, Moscow, Russia.
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Abramochkin DV, Pustovit OB, Mironov NY, Filatova TS, Nesterova T. Characterization of hERG K + channel inhibition by the new class III antiarrhythmic drug cavutilide. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024; 397:5093-5104. [PMID: 38224347 DOI: 10.1007/s00210-023-02940-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 12/30/2023] [Indexed: 01/16/2024]
Abstract
Cavutilide (niferidil, refralon) is a new class III antiarrhythmic drug which effectively terminates persistent atrial fibrillation (AF; 84.6% of patients, mean AF duration 3 months) and demonstrates low risk of torsade de pointes (1.7%). ERG channels of rapid delayed rectifier current(IKr) are the primary target of cavutilide, but the particular reasons of higher effectiveness and lower proarrhythmic risk in comparison with other class III IKr blockers are unclear. The inhibition of hERG channels expressed in CHO-K1 cells by cavutilide was studied using whole-cell patch-clamp. The present study demonstrates high sensitivity of IhERG expressed in CHO-K1 cells to cavutilide (IC50 = 12.8 nM). Similarly to methanesulfonanilide class III agents, but unlike amiodarone and related drugs, cavutilide does not bind to hERG channels in their resting state. However, in contrast to dofetilide, cavutilide binds not only to opened, but also to inactivated channels. Moreover, at positive constantly set membrane potential (+ 60 mV) inhibition of IhERG by 100 nM cavutilide develops faster than at 0 mV and, especially, - 30 mV (τ of inhibition was 78.8, 103, and 153 ms, respectively). Thereby, cavutilide produces IhERG inhibition only when the cell is depolarized. During the same period of time, cavutilide produces greater block of IhERG when the cell is depolarized with 2 Hz frequency, if compared to 0.2 Hz. We suggest that, during the limited time after injection, cavutilide produces stronger inhibition of IKr in fibrillating atrium than in non-fibrillating ventricle. This leads to beneficial combination of antiarrhythmic effectiveness and low proarrhythmicity of cavutilide.
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Affiliation(s)
- Denis V Abramochkin
- Department of Human and Animal Physiology, Biological Faculty, Lomonosov Moscow State University, Leninskiye Gory, 1, 12, Moscow, Russia.
| | - Oksana B Pustovit
- Department of Human and Animal Physiology, Biological Faculty, Lomonosov Moscow State University, Leninskiye Gory, 1, 12, Moscow, Russia
| | | | - Tatiana S Filatova
- Department of Human and Animal Physiology, Biological Faculty, Lomonosov Moscow State University, Leninskiye Gory, 1, 12, Moscow, Russia
- Chazov National Medical Research Center for Cardiology, Moscow, Russia
- Department of Physiology, Pirogov Russian National Research Medical University, Ostrovityanova str., 1, Moscow, Russia
| | - Tatiana Nesterova
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 620049, Ekaterinburg, Russia
- Institute of Natural Sciences and Mathematics, Ural Federal University, 620075, Ekaterinburg, Russia
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Beliaeva MM, Dzaurova KM, Yuricheva YA, Novikov PS, Mironov NY, Tarasovskiy GS, Zelberg MA, Sokolov SF, Golitsyn SP. Intravenous Cavutilide for Pharmacological Conversion of Paroxysmal and Persistent Atrial Fibrillation in Patients with Heart Failure. J Cardiovasc Dev Dis 2023; 10:487. [PMID: 38132655 PMCID: PMC10744291 DOI: 10.3390/jcdd10120487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 11/15/2023] [Accepted: 11/26/2023] [Indexed: 12/23/2023] Open
Abstract
This work aimed to study the efficacy and safety of the class III antiarrhythmic agent cavutilide (Niferidil, Refralon) for pharmacological cardioversion in patients with paroxysmal and persistent atrial fibrillation (AF) and heart failure (HF). METHODS AND RESULTS In this retrospective cohort study, 58 patients with stable HF (aged 69 [61;73] years, 30 males, 78% with persistent AF) and 274 patients without HF (aged 63 [57;70] years, 196 males, 56% with persistent AF) were included. The median AF duration in the group with HF was 35.5 [10.6;124] days, and that in the group without HF was 14.5 [3.6;90] days. All patients received 5-30 µg/kg cavutilide intravenously in one to four (if needed) boluses of 5-5-10-10 µg/kg at 15 min intervals. Subsequent boluses were not administered if the patient's sinus rhythm (SR) was restored or if bradycardia, QT prolongation > 500 ms or evidence of proarrhythmia was observed. Holter electrocardiogram monitoring was started before infusion and was continued for 24 h. The main criterion for an antiarrhythmic effect was sinus rhythm restoration within 24 h of the initial bolus. RESULTS Cavutilide converted AF to SR in 37.9% of patients with HF after bolus 1 (5 µg/kg), in 58.6% after bolus 2 (cumulative dose = 10 µg/kg), in 74% of cases after bolus 3 (cumulative dose = 20 µg/kg) and in 92.8% of cases after bolus 4 (cumulative dose = 30 µg/kg). Cavutilide was effective in 89% of cases with persistent AF with a median duration of 70.5 [30;159] days and in 92% of cases with paroxysmal AF with a median duration of 36 [24;102] h. In the group of patients without HF, the effectiveness of bolus 1 was 36.9%, that of the bolus 2 was 58%, that of the bolus 3 was 77% and that of the bolus 4 was 90.1%. Cavutilide restored SR in 90% of patients with persistent AF with a median duration of 82.5 [28;180] days and in 90% of cases with paroxysmal AF with a median duration of 50 [24;120] h. No statistically significant difference in the probability of SR restoration or the effectiveness of each bolus of cavutilide was found between patients with and without HF. The median time to restoration of SR in patients with HF was 23 [11;55] min, and that in patients without HF was 22 [10;45] min (p = 0.424). No cases of symptomatic/severe bradycardia were observed in either group. QT prolongation over 500 ms after cavutilide injection was registered in 19% of patients without HF and in 15.5% of those with HF (p = 0.58). Short runs of Torsade de pointes tachycardia occurred in one patient (0.4%) without HF after 10 µg cavutilide administration and were successfully treated with MgSO4. CONCLUSIONS Cavutilide demonstrated a high likelihood of AF conversion to SR in paroxysmal (92%) and persistent (89%) arrhythmia and HF. Concomitant HF and its severity do not affect the efficacy and safety of cavutilide.
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Affiliation(s)
- Maria M. Beliaeva
- Federal State Budgetary Institution, National Medical Research Centre of Cardiology Named after Academic E.I.Chazov of the Ministry of Health of the Russian Federation, Academician Chazov str., 15a, Moscow 121552, Russia
| | | | - Yulia A. Yuricheva
- Federal State Budgetary Institution, National Medical Research Centre of Cardiology Named after Academic E.I.Chazov of the Ministry of Health of the Russian Federation, Academician Chazov str., 15a, Moscow 121552, Russia
| | - Peter S. Novikov
- Federal State Budgetary Institution, National Medical Research Centre of Cardiology Named after Academic E.I.Chazov of the Ministry of Health of the Russian Federation, Academician Chazov str., 15a, Moscow 121552, Russia
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Abramochkin DV, Pustovit OB, Mironov NY, Filatova TS, Kuzmin VS. The Dependence of the Electrophysiological Effects of Class III Antiarrhythmic Drug Refralon on the Frequency of Myocardium Activation. Bull Exp Biol Med 2023; 174:610-615. [PMID: 37040036 DOI: 10.1007/s10517-023-05756-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Indexed: 04/12/2023]
Abstract
We studied the frequency dependence of the effects of the novel Russian class III antiarrhythmic drug refralon on the duration of action potentials (AP) in rabbit ventricular myocardium. The absence of an inverse frequency dependence of AP prolongation was demonstrated: the effects of refralon at stimulation frequency of 1 Hz were stronger than at 0.1 Hz. The patch-clamp experiments with recording of rapid delayed rectifier potassium current IKr in a heterologous expression system showed that the blocking effect of refralon developed significantly faster at 2 Hz depolarization frequency than at 0.2 Hz. This feature of refralon distinguishes it among the majority of other class III drugs (sotalol, dofetilide, E-4031) and explains the relatively high safety of this drug together with its high efficacy.
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Affiliation(s)
- D V Abramochkin
- Department of Human and Animal Physiology, M. V. Lomonosov Moscow State University, Moscow, Russia.
- E. I. Chazov National Medical Research Center of Cardiology, Ministry of Health of the Russian Federation, Moscow, Russia.
- Scientific Research Laboratory of Electrophysiology, Pirogov Russian National Research Medical University, Ministry of Health of the Russian Federation, Moscow, Russia.
| | - O B Pustovit
- Department of Human and Animal Physiology, M. V. Lomonosov Moscow State University, Moscow, Russia
| | - N Yu Mironov
- E. I. Chazov National Medical Research Center of Cardiology, Ministry of Health of the Russian Federation, Moscow, Russia
| | - T S Filatova
- Department of Human and Animal Physiology, M. V. Lomonosov Moscow State University, Moscow, Russia
| | - V S Kuzmin
- Department of Human and Animal Physiology, M. V. Lomonosov Moscow State University, Moscow, Russia
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Geng M, Lin A, Nguyen TP. Revisiting Antiarrhythmic Drug Therapy for Atrial Fibrillation: Reviewing Lessons Learned and Redefining Therapeutic Paradigms. Front Pharmacol 2020; 11:581837. [PMID: 33240090 PMCID: PMC7680856 DOI: 10.3389/fphar.2020.581837] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 09/17/2020] [Indexed: 12/12/2022] Open
Abstract
Since the clinical use of digitalis as the first pharmacological therapy for atrial fibrillation (AF) 235 years ago in 1785, antiarrhythmic drug therapy has advanced considerably and become a cornerstone of AF clinical management. Yet, a preventive or curative panacea for sustained AF does not exist despite the rise of AF global prevalence to epidemiological proportions. While multiple elevated risk factors for AF have been established, the natural history and etiology of AF remain incompletely understood. In the present article, the first section selectively highlights some disappointing shortcomings and current efforts in antiarrhythmic drug therapy to uncover reasons why AF is such a clinical challenge. The second section discusses some modern takes on the natural history of AF as a relentless, progressive fibro-inflammatory "atriomyopathy." The final section emphasizes the need to redefine therapeutic strategies on par with new insights of AF pathophysiology.
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Affiliation(s)
| | | | - Thao P. Nguyen
- Division of Cardiology, Department of Medicine, The Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
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Abramochkin DV, Kuzmin VS, Rosenshtraukh LV. A New Class III Antiarrhythmic Drug Niferidil Prolongs Action Potentials in Guinea Pig Atrial Myocardium via Inhibition of Rapid Delayed Rectifier. Cardiovasc Drugs Ther 2017; 31:525-533. [PMID: 29181609 DOI: 10.1007/s10557-017-6762-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE A new class III antiarrhythmic drug niferidil (RG-2) has been introduced as a highly effective therapy for cases of persistent atrial fibrillation, but ionic mechanisms of its action are poorly understood. In the present study, the effects of niferidil on action potential (AP) waveform and potassium currents responsible for AP repolarization were investigated in guinea pig atrial myocardium. METHODS APs were recorded with sharp glass microelectrodes in multicellular atrial preparations. Whole-cell patch-clamp technique was used to measure K+ currents in isolated myocytes. RESULTS In multicellular atrial preparations, 10-8 M niferidil effectively prolonged APs by 15.2 ± 2.8% at 90% repolarization level. However, even the highest tested concentrations, 10-6 M and 10-5 M failed to prolong APs more than 32.5% of control duration. The estimated concentration of niferedil for half-maximal AP prolongation was 1.13 × 10-8 M. Among the potassium currents responsible for AP repolarization phase, I K1 was found to be almost insensitive to niferidil. However, another inward rectifier, I KACh, was effectively suppressed by micromolar concentrations of niferidil with IC50 = 9.2 × 10-6 M. I KATP was much less sensitive to the drug with IC50 = 2.26 × 10-4 M. The slow component of delayed rectifier, I Ks, also demonstrated low sensitivity to niferidil-the highest used concentration, 10-4 M, decreased peak I Ks density to 46.2 ± 5.5% of control. Unlike I Ks, the rapid component of delayed rectifier, I Kr, appeared to be extremely sensitive to niferidil. The IC50 was 1.26 × 10-9 M. I Kr measured in ventricular myocytes was found to be less sensitive to niferidil with IC50 = 3.82 × 10-8 M. CONCLUSIONS Niferidil prolongs APs in guinea pig atrial myocardium via inhibition of I Kr.
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Affiliation(s)
- Denis V Abramochkin
- Lomonosov Moscow State University, Moscow, Russia. .,Pirogov Russian National Research Medical University, Moscow, Russia. .,Department of Human and Animal Physiology, Moscow State University, Leninskije Gory, 1, 12, Moscow, Russia.
| | - Vladislav S Kuzmin
- Lomonosov Moscow State University, Moscow, Russia.,Pirogov Russian National Research Medical University, Moscow, Russia.,Institute of Experimental Cardiology, Moscow, Russia
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Effects of new class III antiarrhythmic drug niferidil on electrical activity in murine ventricular myocardium and their ionic mechanisms. Naunyn Schmiedebergs Arch Pharmacol 2015; 388:1105-12. [PMID: 26105002 DOI: 10.1007/s00210-015-1146-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 06/11/2015] [Indexed: 10/23/2022]
Abstract
A new class III antiarrhythmic drug niferidil has been recently introduced as a highly effective therapy cure for cases of persistent atrial fibrillation, but ionic mechanisms of its action are still unknown. Effects of niferidil on action potential (AP) waveform and major ionic currents were studied in mouse ventricular myocardium. APs were recorded with glass microelectrodes in multicellular preparations of right ventricular wall. Whole-cell patch-clamp technique was used to measure K(+), Ca(2+), and Na(+) currents in isolated mouse ventricular myocytes. While 10(-7) M niferidil failed to alter the AP configuration, 10(-6) M tended to prolong APs (by 12.05 ± 1.8% at 50% of repolarization) and 10(-5) M induced significant slowing of repolarization (32.1 ± 4.9% at 50% of repolarization). Among the potassium currents responsible for AP repolarization phase, IK1 was found to be almost insensitive to niferidil. Ito demonstrated low sensitivity to niferidil with IC50 = 2.03 × 10(-4) M. IKur, which was previously hypothesized to be the main target of the drug, was more sensitive with IC50 = 6 × 10(-5) M. However, sustained delayed rectifier potassium current Iss was inhibited with even lower IC50 = 2.8 × 10(-5) M. Therefore, suppression of Iss and, second, IKur by niferidil seems to underlie the AP prolongation in mouse ventricular tissue. Niferidil also produced a modest decrease in ICaL peak amplitude (IC50≈10(-4) M), but failed to alter INa significantly. Niferidil prolongs APs in mouse ventricular myocardium mainly by inhibiting Iss and IKur K(+) currents, but not exclusively IKur, as was proposed earlier. Further investigations are required to reveal the mechanisms of niferidil action in human myocardium, where IKr is strongly expressed instead of Iss.
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