1
|
Hemmeryckx B, Feng Y, Frederix L, Lox M, Trenson S, Vreeken R, Lu HR, Gallacher D, Ni Y, Lijnen HR. Evaluation of cardiac arrhythmic risks using a rabbit model of left ventricular systolic dysfunction. Eur J Pharmacol 2018; 832:145-155. [PMID: 29782862 DOI: 10.1016/j.ejphar.2018.05.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 05/17/2018] [Accepted: 05/17/2018] [Indexed: 12/13/2022]
Abstract
Patients with heart disease have a higher risk to develop cardiac arrhythmias, either spontaneously or drug-induced. In this study, we have used a rabbit model of myocardial infarction (MI) with severe left ventricular systolic dysfunction (LVSD) to study potential drug-induced cardiac risks with N-(piperidin-2-ylmethyl)-2,5-bis(2,2,2-trifluoroethoxy)benzamide (flecainide). Upon ligation of the left circumflex arteries, male New Zealand White rabbits developed a large MI and moderate or severe LVSD 7 weeks after surgery, in comparison to SHAM-operated animals. Subsequently, animals were exposed to escalating doses of flecainide (0.25-4 mg/kg) or solvent. Electrocardiograms (ECG) were recorded before surgery, 1 and 7 weeks after surgery and continuously during the drug protocol. The ECG biomarker iCEB (index of Cardio-Electrophysiological Balance = QT/QRS ratio) was calculated. During the ECG recording at week 1 and week 7 post MI, rabbits had no spontaneous cardiac arrhythmias. When rabbits were exposed to escalating doses of flecainide, 2 out of 5 rabbits with MI and moderate LVSD versus 0 out of 5 solvent-treated rabbits developed arrhythmias, such as ventricular tachycardia/ventricular fibrillation. These were preceded by a marked decrease of iCEB just before the onset (from 4.09 to 2.42 and from 5.56 to 2.25, respectively). Furthermore, 1 out of 5 MI rabbits with moderate LVSD and 1 out of 7 MI rabbits with severe LVSD developed total atrioventricular block after flecainide infusion and died. This rabbit model of MI and severe LVSD may be useful for preclinical evaluation of drug (similar mechanism as flecainide)-induced arrhythmic risks, which might be predicted by iCEB.
Collapse
Affiliation(s)
- Bianca Hemmeryckx
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
| | - Yuanbo Feng
- Radiology, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium.
| | - Liesbeth Frederix
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
| | - Marleen Lox
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
| | - Sander Trenson
- Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
| | - Rob Vreeken
- Metabolomics, Pharmacokinetics, Dynamics and Metabolism Discovery Sciences, Janssen Pharmaceutical NV, Beerse, Belgium.
| | - Hua Rong Lu
- Translational Sciences, Safety Pharmacology Research, Janssen Research & Development, Janssen Pharmaceutical NV, Beerse, Belgium.
| | - David Gallacher
- Translational Sciences, Safety Pharmacology Research, Janssen Research & Development, Janssen Pharmaceutical NV, Beerse, Belgium.
| | - Yicheng Ni
- Radiology, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium.
| | - H Roger Lijnen
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
| |
Collapse
|
2
|
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.
Collapse
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.
| |
Collapse
|
3
|
KN-93, A CaMKII inhibitor, suppresses ventricular arrhythmia induced by LQT2 without decreasing TDR. ACTA ACUST UNITED AC 2013; 33:636-639. [PMID: 24142712 DOI: 10.1007/s11596-013-1172-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 08/13/2013] [Indexed: 10/26/2022]
Abstract
Abnormal enhanced transmural dispersion of repolarization (TDR) plays an important role in the maintaining of the severe ventricular arrhythmias such as torsades de pointes (TDP) which can be induced in long-QT (LQT) syndrome. Taking advantage of an in vitro rabbit model of LQT2, we detected the effects of KN-93, a CaM-dependent kinase (CaMK) II inhibitor on repolarization heterogeneity of ventricular myocardium. Using the monophasic action potential recording technique, the action potentials of epicardium and endocardium were recorded in rabbit cardiac wedge infused with hypokalemic, hypomagnesaemic Tyrode's solution. At a basic length (BCL) of 2000 ms, LQT2 model was successfully mimicked with the perfusion of 0.5 μmol/L E-4031, QT intervals and the interval from the peak of T wave to the end of T wave (Tp-e) were prolonged, and Tp-e/QT increased. Besides, TDR was increased and the occurrence rate of arrhythmias like EAD, R-on-T extrasystole, and TDP increased under the above condition. Pretreatment with KN-93 (0.5 μmol/L) could inhibit EAD, R-on-T extrasystole, and TDP induced by E-4031 without affecting QT interval, Tp-e, and Tp-e/QT. This study demonstrated KN-93, a CaMKII inhibitor, can inhibit EADs which are the triggers of TDP, resulting in the suppression of TDP induced by LQT2 without affecting TDR.
Collapse
|
4
|
Lu HR, Yan GX, Gallacher DJ. A new biomarker--index of cardiac electrophysiological balance (iCEB)--plays an important role in drug-induced cardiac arrhythmias: beyond QT-prolongation and Torsades de Pointes (TdPs). J Pharmacol Toxicol Methods 2013; 68:250-259. [PMID: 23337247 DOI: 10.1016/j.vascn.2013.01.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 01/02/2013] [Accepted: 01/05/2013] [Indexed: 12/15/2022]
Abstract
INTRODUCTION In the present study, we investigated whether a new biomarker - index of cardiac electrophysiological balance (iCEB=QT/QRS) - could predict drug-induced cardiac arrhythmias (CAs), including ventricular tachycardia/ventricular fibrillation (VT/VF) and Torsades de Pointes (TdPs). METHODS The rabbit left ventricular arterially-perfused-wedge was used to investigate whether the simple iCEB measured from the ECG is reflective of the more difficult measurement of λ (effective refractory period×conduction velocity) for predicting CAs induced by a number of drugs. RESULTS Dofetilide concentration-dependently increased iCEB and λ, predicting potential risk of drug-induced incidence of early afterdepolarizations (EADs) starting at 0.01μM. Digoxin (1 and 5μM), encainide (5 and 20μM) and propoxyphene (10 and 100μM) markedly reduced both iCEB and λ, predicting their ability to induce non-TdP-like VT/VF. At 10μM, both NS1643 and levcromakalim significantly decreased λ and iCEB, which was preceded with presence of non-TdP-like VT/VF. Isoprenaline (0.05 to 0.5μM) significantly reduced both λ and iCEB, which was associated with a high incidence of non-TdP-like VT/VF in most preparations. Other biomarkers (i.e. transmural dispersion of T-wave and instability of the QT interval) predicted only dofetilide-induced long QT and EADs, but did not predict drug-induced risk of non-TdP-like VT/VF. DISCUSSION Our data from 7 reference drugs of known pro-arrhythmic effects suggests that 1) this non-invasive iCEB predicts potential risk of drug-induced CAs beyond long QT and TdP; 2) iCEB is more useful than the current biomarkers (i.e. transmural dispersion and instability) in predicting potential risks for drug-induced non-TdP-like VT/VF.
Collapse
Affiliation(s)
- Hua Rong Lu
- Janssen Research and Development, Janssen Pharmaceutica NV, Belgium.
| | - Gan-Xin Yan
- Main Line Health Heart Center and Lankenau Institute for Medical Research, Wynnewood, PA, USA
| | | |
Collapse
|
5
|
Antiarrhythmic effects of free polyunsaturated fatty acids in an experimental model of LQT2 and LQT3 due to suppression of early afterdepolarizations and reduction of spatial and temporal dispersion of repolarization. Heart Rhythm 2011; 8:1492-500. [PMID: 21459164 DOI: 10.1016/j.hrthm.2011.03.058] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Accepted: 03/25/2011] [Indexed: 11/23/2022]
Abstract
BACKGROUND Torsades de pointes (TdP) are induced by early afterdepolarizations (EADs) in the presence of an increased dispersion of repolarization. Free polyunsaturated fatty acids (PUFAs) have been suggested to influence cardiac repolarization. OBJECTIVE The purpose of this experimental study was to investigate the electrophysiologic effects of PUFAs in a model of LQT2 and LQT3. METHODS We investigated the acute antiarrhythmic potential of α-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) in a whole-heart model of long QT2 (LQT2) and long QT3 (LQT3) syndrome. RESULTS In 123 Langendorff-perfused rabbit hearts, the I(Kr)-blocking drug erythromycin (E; 300 μM) or veratridine (V; 0.5 μM), an inhibitor of sodium channel inactivation, significantly increased monophasic ventricular action potentials (MAPs), thereby mimicking LQT2 and LQT3 syndrome. In atrioventricular-blocked hearts, 8 epicardial and endocardial MAPs demonstrated a significant increase in spatial and temporal dispersion. After lowering potassium concentration, E led to EADs and TdP in 44 and 41 of 53 hearts, respectively. Pretreatment with V led to EAD (TdP) in 39 (32) of 43 hearts. Additional treatment with ALA, DHA, or EPA (10 to 20 μM) in the LQT2 model, randomly assigned to 3 groups, suppressed EAD in 72% of ALA-treated hearts and in all hearts that were treated with EPA or DHA. This led to a reduction of TdP of 67% (ALA) and to complete abolishment of TdP in all hearts that were treated with EPA or DHA. A comparable finding was seen in V-pretreated hearts. In addition, DHA and EPA significantly shortened MAP duration and reduced spatial and temporal dispersion of repolarization (P <.01). CONCLUSION The present study showed for the first time that PUFAs are effective in preventing TdP in an experimental model of LQT2 and LQT3 syndrome due to a reversion of AP prolongation, a reduction of spatial and temporal dispersion of repolarization and a suppression of EAD. The PUFA effect is stronger in LQT2 than in LQT3 syndrome, and the antitorsadogenic effect is more remarkable with DHA and EPA as compared with ALA.
Collapse
|
6
|
Zhang XH, Jin MW, Sun HY, Zhang S, Li GR. The calmodulin inhibitor N-(6-aminohexyl)-5-chloro-1-naphthalene sulphonamide directly blocks human ether à-go-go-related gene potassium channels stably expressed in human embryonic kidney 293 cells. Br J Pharmacol 2010; 161:872-84. [PMID: 20860665 DOI: 10.1111/j.1476-5381.2010.00916.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE N-(6-aminohexyl)-5-chloro-1-naphthalene sulphonamide (W-7) is a well-known calmodulin inhibitor used to study calmodulin regulation of intracellular Ca(2+) signalling-related process. Here, we have determined whether W-7 would inhibit human ether gene (hERG or K(v) 11.1) potassium channels, hK(v) 1.5 channels or hK(IR) 2.1 channels expressed in human embryonic kidney (HEK) 293 cells. EXPERIMENTAL APPROACH The hERG channel current, hK(v) 1.5 channel current or hK(IR) 2.1 channel current was recorded with a whole-cell patch clamp technique. KEY RESULTS It was found that the calmodulin inhibitor W-7 blocked hERG, hK(v) 1.5 and hK(IR) 2.1 channels. W-7 decreased the hERG current (I(hERG) ) in a concentration-dependent manner (IC(50) : 3.5 µM), and the inhibition was more significant at depolarization potentials between +10 and +60 mV. The hERG mutations in the S6 region Y652A and F656V, and in the pore helix S631A, had the IC(50) s of 5.5, 9.8 and 25.4 µM respectively. In addition, the compound inhibited hK(v) 1.5 and hK(IR) 2.1 channels with IC(50) s of 6.5 and 13.4 µM respectively. CONCLUSION AND IMPLICATIONS These results indicate that the calmodulin inhibitor W-7 exerts a direct channel-blocking effect on hERG, hK(v) 1.5 and hK(IR) 2.1 channels stably expressed in HEK 293 cells. Caution should be taken in the interpretation of calmodulin regulation of ion channels with W-7.
Collapse
Affiliation(s)
- Xiao-Hua Zhang
- Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | | | | | | | | |
Collapse
|
7
|
Antoons G, Thomsen MB. Repolarization variability and early afterdepolarizations in long QT syndrome type 2: Is labile calcium the common denominator? Heart Rhythm 2010; 7:1695-6. [DOI: 10.1016/j.hrthm.2010.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Indexed: 10/19/2022]
|
8
|
Celotto AC, Capellini VK, Restini CBA, Baldo CF, Bendhack LM, Evora PRB. Extracellular alkalinization induces endothelium-derived nitric oxide dependent relaxation in rat thoracic aorta. Nitric Oxide 2010; 23:269-74. [PMID: 20682356 DOI: 10.1016/j.niox.2010.07.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 07/10/2010] [Accepted: 07/29/2010] [Indexed: 10/19/2022]
Abstract
AIM To investigate the mechanism through which the extracellular alkalinization promotes relaxation in rat thoracic aorta. METHODS The relaxation response to NaOH-induced extracellular alkalinization (7.4-8.5) was measured in aortic rings pre-contracted with phenylephrine (Phe, 10(-6) M). The vascular reactivity experiments were performed in endothelium-intact and -denuded rings, in the presence or and absence of indomethacin (10(-5) M), NG-nitro-l-arginine methyl ester (L-NAME, 10(-4) M), N-(6-Aminohexyl)-5-chloro-1-naphthalenesulfonamide/HCl (W-7, 10(-7) M), 2,5-dimethylbenzimidazole (DMB, 2×10(-5) M) and methyl-β-cyclodextrin (10(-2) M). In addition, the effects of NaOH-induced extracellular alkalinization (pH 8.0 and 8.5) on the intracellular nitric oxide (NO) concentration was evaluated in isolated endothelial cells loaded with diaminofluorescein-FM diacetate (DAF-FM DA, 5 μM), in the presence and absence of DMB (2×10(-5) M). RESULTS The extracellular alkalinization failed to induce any change in vascular tone in aortic rings pre-contracted with KCl. In rings pre-contracted with Phe, the extracellular alkalinization caused relaxation in the endothelium-intact rings only, and this relaxation was maintained after cyclooxygenase inhibition; completely abolished by the inhibition of nitric oxide synthase (NOS), Ca(2+)/calmodulin and Na(+)/Ca(2+) exchanger (NCX), and partially blunted by the caveolae disassembly. CONCLUSIONS These results suggest that, in rat thoracic aorta, that extracellular alkalinization with NaOH activates the NCX reverse mode of endothelial cells in rat thoracic aorta, thereby the intracellular Ca(2+) concentration and activating the Ca(2+)/calmodulin-dependent NOS. In turn, NO is released promoting relaxation.
Collapse
Affiliation(s)
- A C Celotto
- Laboratory of Endothelial Function, Department of Surgery and Anatomy, School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil
| | | | | | | | | | | |
Collapse
|
9
|
Raschi E, Ceccarini L, De Ponti F, Recanatini M. hERG-related drug toxicity and models for predicting hERG liability and QT prolongation. Expert Opin Drug Metab Toxicol 2009; 5:1005-21. [PMID: 19572824 DOI: 10.1517/17425250903055070] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
BACKGROUND hERG K(+) channels have been recognized as a primary antitarget in safety pharmacology. Their blockade, caused by several drugs with different therapeutic indications, may lead to QT prolongation and, eventually, to potentially fatal arrhythmia, namely torsade de pointes. Therefore, a number of preclinical models have been developed to predict hERG liability early in the drug development process. OBJECTIVE The aim of this review is to outline the present state of the art on drug-induced hERG blockade, providing insights on the predictive value of in vitro and in silico models for hERG liability. METHODS On the basis of latest reports, high-throughput preclinical models have been discussed outlining advantages and limitations. CONCLUSION Although no single model has an absolute value, an integrated risk assessment is recommended to predict the pro-arrhythmic risk of a given drug. This prediction requires expertise from different areas and should encompass emerging issues such as interference with hERG trafficking and QT shortening.
Collapse
Affiliation(s)
- Emanuel Raschi
- University of Bologna, Department of Pharmacology, Italy
| | | | | | | |
Collapse
|
10
|
Takahara A, Nakamura Y, Wagatsuma H, Aritomi S, Nakayama A, Satoh Y, Akie Y, Sugiyama A. Long-term blockade of L/N-type Ca(2+) channels by cilnidipine ameliorates repolarization abnormality of the canine hypertrophied heart. Br J Pharmacol 2009; 158:1366-74. [PMID: 19785655 PMCID: PMC2782346 DOI: 10.1111/j.1476-5381.2009.00407.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 05/27/2009] [Accepted: 06/09/2009] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE The heart of the canine model of chronic atrioventricular block is known to have a ventricular electrical remodelling, which mimics the pathophysiology of long QT syndrome. Using this model, we explored a new pharmacological therapeutic strategy for the prevention of cardiac sudden death. EXPERIMENTAL APPROACH The L-type Ca(2+) channel blocker amlodipine (2.5 mg.day(-1)), L/N-type Ca(2+) channel blocker cilnidipine (5 mg.day(-1)), or the angiotensin II receptor blocker candesartan (12 mg.day(-1)) was administered orally to the dogs with chronic atrioventricular block for 4 weeks. Electropharmacological assessments with the monophasic action potential (MAP) recordings and blood sample analyses were performed before and 4 weeks after the start of drug administration. KEY RESULTS Amlodipine and cilnidipine decreased the blood pressure, while candesartan hardly affected it. The QT interval, MAP duration and beat-to-beat variability of the ventricular repolarization period were shortened only in the cilnidipine group, but such effects were not observed in the amlodipine or candesartan group. Plasma concentrations of adrenaline, angiotensin II and aldosterone decreased in the cilnidipine group. In contrast, plasma concentrations of angiotensin II and aldosterone were elevated in the amlodipine group, whereas in the candesartan group an increase in plasma levels of angiotensin II and a decrease in noradrenaline and adrenaline concentrations were observed. CONCLUSIONS AND IMPLICATIONS Long-term blockade of L/N-type Ca(2+) channels ameliorated the ventricular electrical remodelling in the hypertrophied heart which causes the prolongation of the QT interval. This could provide a novel therapeutic strategy for the treatment of cardiovascular diseases.
Collapse
Affiliation(s)
- A Takahara
- Department of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Cubeddu LX. Iatrogenic QT Abnormalities and Fatal Arrhythmias: Mechanisms and Clinical Significance. Curr Cardiol Rev 2009; 5:166-76. [PMID: 20676275 PMCID: PMC2822139 DOI: 10.2174/157340309788970397] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Revised: 01/30/2009] [Accepted: 01/31/2009] [Indexed: 11/22/2022] Open
Abstract
Severe and occasionally fatal arrhythmias, commonly presenting as Torsade de Pointes [TdP] have been reported with Class III-antiarrhythmics, but also with non-antiarrhythmic drugs. Most cases result from an action on K(+) channels encoded by the HERG gene responsible for the IKr repolarizing current, leading to a long QT and repolarization abnormalities. The hydrophobic central cavity of the HERG-K+ channels, allows a large number of structurally unrelated drugs to bind and cause direct channel inhibition. Some examples are dofetilide, quinidine, sotalol, erythromycin, grepafloxacin, cisapride, dolasetron, thioridazine, haloperidol, droperidol and pimozide. Other drugs achieve channel inhibition indirectly by impairing channel traffic from the endoplasmic reticulum to the cell membrane, decreasing channel membrane density (pentamidine, geldalamicin, arsenic trioxide, digoxin, and probucol). Whereas, ketoconazole, fluoxetine and norfluoxetine induce both direct channel inhibition and impaired channel trafficking. Congenital long QT syndrome, subclinical ion-channel mutations, subjects and relatives of subjects with previous history of drug-induced long QT or TdP, dual drug effects on cardiac repolarization [long QT plus increased QT dispersion], increased transmural dispersion of repolarization and T wave abnormalities, use of high doses, metabolism inhibitors and/or combinations of QT prolonging drugs, hypokalemia, structural cardiac disease, sympathomimetics, bradycardia, women and older age, have been shown to increase the risk for developing drug-induced TdP. Because most of these reactions are preventable, careful evaluation of risk factors and increased knowledge of drugs use associated with repolarization abnormalities is strongly recommended. Future genetic testing and development of practical and simple provocation tests are in route to prevent iatrogenic TdP.
Collapse
Affiliation(s)
- Luigi X Cubeddu
- Nova Southeastern University, HPD, Cardiovascular and Metabolic Research Division, Fort Lauderdale, FL, USA
| |
Collapse
|
12
|
Bass AS, Darpo B, Breidenbach A, Bruse K, Feldman HS, Garnes D, Hammond T, Haverkamp W, January C, Koerner J, Lawrence C, Leishman D, Roden D, Valentin JP, Vos MA, Zhou YY, Karluss T, Sager P. International Life Sciences Institute (Health and Environmental Sciences Institute, HESI) initiative on moving towards better predictors of drug-induced torsades de pointes. Br J Pharmacol 2008; 154:1491-501. [PMID: 18663380 PMCID: PMC2492102 DOI: 10.1038/bjp.2008.279] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Accepted: 06/12/2008] [Indexed: 12/19/2022] Open
Abstract
Knowledge of the cardiac safety of emerging new drugs is an important aspect of assuring the expeditious advancement of the best candidates targeted at unmet medical needs while also assuring the safety of clinical trial subjects or patients. Present methodologies for assessing drug-induced torsades de pointes (TdP) are woefully inadequate in terms of their specificity to select pharmaceutical agents, which are human arrhythmia toxicants. Thus, the critical challenge in the pharmaceutical industry today is to identify experimental models, composite strategies, or biomarkers of cardiac risk that can distinguish a drug, which prolongs cardiac ventricular repolarization, but is not proarrhythmic, from one that prolongs the QT interval and leads to TdP. To that end, the HESI Proarrhythmia Models Project Committee recognized that there was little practical understanding of the relationship between drug effects on cardiac ventricular repolarization and the rare clinical event of TdP. It was on that basis that a workshop was convened in Virginia, USA at which four topics were introduced by invited subject matter experts in the following fields: Molecular and Cellular Biology Underlying TdP, Dynamics of Periodicity, Models of TdP Proarrhythmia, and Key Considerations for Demonstrating Utility of Pre-Clinical Models. Contained in this special issue of the British Journal of Pharmacology are reports from each of the presenters that set out the background and key areas of discussion in each of these topic areas. Based on this information, the scientific community is encouraged to consider the ideas advanced in this workshop and to contribute to these important areas of investigations over the next several years.
Collapse
Affiliation(s)
- A S Bass
- Drug Safety and Metabolism, Schering-Plough Research Institute, Kenilworth, NJ 07033-0539, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Muster W, Breidenbach A, Fischer H, Kirchner S, Müller L, Pähler A. Computational toxicology in drug development. Drug Discov Today 2008; 13:303-10. [DOI: 10.1016/j.drudis.2007.12.007] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Revised: 12/17/2007] [Accepted: 12/18/2007] [Indexed: 10/22/2022]
|
14
|
Raschi E, Vasina V, Poluzzi E, De Ponti F. The hERG K+ channel: target and antitarget strategies in drug development. Pharmacol Res 2008; 57:181-95. [PMID: 18329284 DOI: 10.1016/j.phrs.2008.01.009] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 01/21/2008] [Accepted: 01/22/2008] [Indexed: 12/16/2022]
Abstract
The human ether-à-go-go related gene (hERG) K+ channel is of great interest for both basic researchers and clinicians because its blockade by drugs can lead to QT prolongation, which is a risk factor for torsades de pointes, a potentially life-threatening arrhythmia. A growing list of agents with "QT liability" have been withdrawn from the market or restricted in their use, whereas others did not even receive regulatory approval for this reason. Thus, hERG K+ channels have become a primary antitarget (i.e. an unwanted target) in drug development because their blockade causes potentially serious side effects. On the other hand, the recent identification and functional characterization of hERG K+ channels not only in the heart, but also in several other tissues (e.g. neurons, smooth muscle and cancer cells) may have far reaching implications for drug development for a possible exploitation of hERG as a target, especially in oncology and cardiology.
Collapse
Affiliation(s)
- Emanuel Raschi
- Department of Pharmacology, University of Bologna, Via Irnerio, 48, I-40126 Bologna BO, Bologna, Italy
| | | | | | | |
Collapse
|
15
|
Choice of cardiac tissue in vitro plays an important role in assessing the risk of drug-induced cardiac arrhythmias in human: Beyond QT prolongation. J Pharmacol Toxicol Methods 2008; 57:1-8. [DOI: 10.1016/j.vascn.2007.06.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Accepted: 06/07/2007] [Indexed: 11/20/2022]
|
16
|
Antoons G, Oros A, Bito V, Sipido KR, Vos MA. Cellular basis for triggered ventricular arrhythmias that occur in the setting of compensated hypertrophy and heart failure: considerations for diagnosis and treatment. J Electrocardiol 2007; 40:S8-14. [DOI: 10.1016/j.jelectrocard.2007.05.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Accepted: 05/30/2007] [Indexed: 10/22/2022]
|
17
|
Michael G, Dempster J, Kane KA, Coker SJ. Potentiation of E-4031-induced torsade de pointes by HMR1556 or ATX-II is not predicted by action potential short-term variability or triangulation. Br J Pharmacol 2007; 152:1215-27. [PMID: 17965747 DOI: 10.1038/sj.bjp.0707513] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Torsade de pointes (TdP) can be induced by a reduction in cardiac repolarizing capacity. The aim of this study was to assess whether IKs blockade or enhancement of INa could potentiate TdP induced by IKr blockade and to investigate whether short-term variability (STV) or triangulation of action potentials preceded TdP. EXPERIMENTAL APPROACH Experiments were performed in open-chest, pentobarbital-anaesthetized, alpha 1-adrenoceptor-stimulated, male New Zealand White rabbits, which received three consecutive i.v. infusions of either the IKr blocker E-4031 (1, 3 and 10 nmol kg(-1) min(-1)), the IKs blocker HMR1556 (25, 75 and 250 nmol kg(-1) min(-1)) or E-4031 and HMR1556 combined. In a second study rabbits received either the same doses of E-4031, the INa enhancer, ATX-II (0.4, 1.2 and 4.0 nmol kg(-1)) or both of these drugs. ECGs and epicardial monophasic action potentials were recorded. KEY RESULTS HMR1556 alone did not cause TdP but increased E-4031-induced TdP from 25 to 80%. ATX-II alone caused TdP in 38% of rabbits, as did E-4031; 75% of rabbits receiving both drugs had TdP. QT intervals were prolonged by all drugs but the extent of QT prolongation was not related to the occurrence of TdP. No changes in STV were detected and triangulation was only increased after TdP occurred. CONCLUSIONS AND IMPLICATIONS Giving modulators of ion channels in combination substantially increased TdP but, in this model, neither STV nor triangulation of action potentials could predict TdP.
Collapse
Affiliation(s)
- G Michael
- Strathclyde Institute of Pharmacy and Biomedical Sciences, Division of Physiology and Pharmacology, University of Strathclyde, Glasgow, UK
| | | | | | | |
Collapse
|
18
|
Abstract
PURPOSE OF REVIEW A wide array of drugs can cause marked QT prolongation with the associated risk of torsade de pointes. The large number of drugs with this potential, the correspondingly large number of patients exposed to such drugs, and the potentially fatal outcome make drug-induced long QT syndrome an important public health problem. This review focuses on mechanisms underlying QT prolongation and proarrhythmia, risk factors, including the role of genetic variants, and the unifying framework of reduced repolarization reserve. RECENT FINDINGS While most drugs that prolong the QT block a specific potassium channel, novel mechanisms altering protein trafficking have been discovered. The progression to torsade de pointes may be less related to degree of QT prolongation than to drug effects on transmural dispersion or variability of repolarization. Our understanding of certain predisposing risk factors has been further refined. SUMMARY Ongoing research continues to elucidate the mechanisms underlying drug-induced long QT syndrome. Importantly, studies are establishing improved predictors of risk for progression to torsade de pointes, in addition to the degree of QT prolongation, which is an imperfect predictor. Nonetheless, drug-induced long QT syndrome and torsade de pointes pose unique challenges for clinicians, researchers, drug-development programs, and regulatory agencies.
Collapse
Affiliation(s)
- Prince J Kannankeril
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
| | | |
Collapse
|
19
|
Qu YJ, Bondarenko VE, Xie C, Wang S, Awayda MS, Strauss HC, Morales MJ. W-7 modulates Kv4.3: pore block and Ca2+-calmodulin inhibition. Am J Physiol Heart Circ Physiol 2007; 292:H2364-77. [PMID: 17220193 DOI: 10.1152/ajpheart.00409.2005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ca(+)-calmodulin (Ca(2+)-CaM)-dependent protein kinase II (Ca(2+)/CaMKII) is an important regulator of cardiac ion channels, and its inhibition may be an approach for treatment of ventricular arrhythmias. Using the two-electrode voltage-clamp technique, we investigated the role of W-7, an inhibitor of Ca(2+)-occupied CaM, and KN-93, an inhibitor of Ca(2+)/CaMKII, on the K(v)4.3 channel in Xenopus laevis oocytes. W-7 caused a voltage- and concentration-dependent decrease in peak current, with IC(50) of 92.4 muM. The block was voltage dependent, with an effective electrical distance of 0.18 +/- 0.05, and use dependence was observed, suggesting that a component of W-7 inhibition of K(v)4.3 current was due to open-channel block. W-7 made recovery from open-state inactivation a biexponential process, also suggesting open-channel block. We compared the effects of W-7 with those of KN-93 after washout of 500 muM BAPTA-AM. KN-93 reduced peak current without evidence of voltage or use dependence. Both W-7 and KN-93 accelerated all components of inactivation. We used wild-type and mutated K(v)4.3 channels with mutant CaMKII consensus phosphorylation sites to examine the effects of W-7 and KN-93. In contrast to W-7, KN-93 at 35 muM selectively accelerated open-state inactivation in the wild-type vs. the mutant channel. W-7 had a significantly greater effect on recovery from inactivation in wild-type than in mutant channels. We conclude that, at certain concentrations, KN-93 selectively inhibits Ca(2+)/CaMKII activity in Xenopus oocytes and that the effects of W-7 are mediated by direct interaction with the channel pore and inhibition of Ca(2+)-CaM, as well as a change in activity of Ca(2+)-CaM-dependent enzymes, including Ca(2+)/CaMKII.
Collapse
Affiliation(s)
- Yu-Jie Qu
- Department of Physiology and Biophysics, School of Medicine and Biomedical Sciences, University at Buffalo-State University of New York, 3435 Main Street, Buffalo, NY 14214, USA
| | | | | | | | | | | | | |
Collapse
|
20
|
Current World Literature. Curr Opin Cardiol 2007; 22:49-53. [PMID: 17143045 DOI: 10.1097/hco.0b013e3280126b20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
21
|
Thomsen MB, Beekman JDM, Attevelt NJM, Takahara A, Sugiyama A, Chiba K, Vos MA. No proarrhythmic properties of the antibiotics Moxifloxacin or Azithromycin in anaesthetized dogs with chronic-AV block. Br J Pharmacol 2006; 149:1039-48. [PMID: 17088870 PMCID: PMC2014631 DOI: 10.1038/sj.bjp.0706900] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND & PURPOSE The therapeutically available quinolone antibiotic moxifloxacin has been used as a positive control for prolonging the QT interval in both clinical and non-clinical studies designed to assess the potential of new drugs to delay cardiac repolarization. Despite moxifloxacin prolonging QT, it has not been shown to cause torsades de pointes arrhythmias (TdP). Azithromycin is a macrolide antibiotic that has rarely been associated, clinically, with cases of proarrhythmia. As there is a lack of clinical data available, the cardiac safety of these drugs was assessed in a TdP-susceptible animal model by evaluating their repolarization and proarrhythmia effects. EXPERIMENTAL APPROACH & KEY RESULTS In transfected HEK cells, the IC(50)s for I (hERG) were 45+/-6 and 856+/-259 microg ml(-1) for moxifloxacin and azithromycin, respectively. Intravenous administration of 2 and 8 mg kg(-1) moxifloxacin (total peak-plasma concentrations 4.6+/-1.5 and 22.9+/-6.8 microg ml(-1)) prolonged the QT(c) in 6 anaesthetized dogs with chronic AV block by 7+/-3 and 21+/-19%, respectively. Similar intravenous doses of azithromycin (total peak-plasma concentrations 5.4+/-1.3 and 20.8+/-4.9 microg ml(-1)) had no electrophysiological effects in the same dogs. The reference compound, dofetilide (25 microg kg(-1) i.v.) caused QT(c) prolongation (29+/-15%) and TdP in all dogs. Beat-to-beat variability of repolarization (BVR), quantified as short-term variability of the left ventricular monophasic action potential duration, was only increased after dofetilide (1.8+/-0.7 to 3.8+/-1.5 ms; P<0.05). CONCLUSION & IMPLICATIONS As neither moxifloxacin nor azithromycin caused TdP or an increase in the BVR, we conclude that both drugs can be used safely in clinical situations.
Collapse
Affiliation(s)
- M B Thomsen
- Department of Medical Physiology, Heart Lung Centre Utrecht, University Medical Center Utrecht Utrecht, The Netherlands
| | - J D M Beekman
- Department of Medical Physiology, Heart Lung Centre Utrecht, University Medical Center Utrecht Utrecht, The Netherlands
| | - N J M Attevelt
- Department of Medical Physiology, Heart Lung Centre Utrecht, University Medical Center Utrecht Utrecht, The Netherlands
| | - A Takahara
- Department of Pharmacology, University of Yamanashi Yamanashi, Japan
| | - A Sugiyama
- Department of Pharmacology, University of Yamanashi Yamanashi, Japan
| | - K Chiba
- New Product Research Laboratories II, Daiichi Pharmaceutical Co., Ltd Tokyo, Japan
| | - M A Vos
- Department of Medical Physiology, Heart Lung Centre Utrecht, University Medical Center Utrecht Utrecht, The Netherlands
- Author for correspondence:
| |
Collapse
|
22
|
Thomsen MB, Volders PGA, Beekman JDM, Matz J, Vos MA. Beat-to-Beat variability of repolarization determines proarrhythmic outcome in dogs susceptible to drug-induced torsades de pointes. J Am Coll Cardiol 2006; 48:1268-76. [PMID: 16979017 DOI: 10.1016/j.jacc.2006.05.048] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Revised: 05/04/2006] [Accepted: 05/09/2006] [Indexed: 01/08/2023]
Abstract
OBJECTIVES We investigated whether increasing or decreasing beat-to-beat variability of repolarization (BVR) would change drug-induced proarrhythmic outcome accordingly. BACKGROUND Increased variability of repolarization has been suggested as a prelude to proarrhythmic circumstances in experimental and clinical situations. METHODS The non-cardiovascular, I(Kr)-blocking drug sertindole was administered to anesthetized dogs with chronic atrioventricular block. Three interventions were used to prevent or suppress sertindole-induced torsades de pointes (TdP). RESULTS Supratherapeutic doses of sertindole (1.0 mg/kg intravenously) induced TdP in 10 of 13 dogs whereas 0.2 mg/kg induced no TdP, despite increases in QT intervals by both doses. The BVR, quantified as short-term variability (STV) from Poincaré plots, was the only parameter that predicted TdP outcome (1.0 mg/kg sertindole: 2.3 +/- 0.7 ms to 5.1 +/- 2.1 ms, p < 0.05; 0.2 mg/kg sertindole: 2.3 +/- 0.8 ms to 3.2 +/- 1.1 ms, p= NS). INTERVENTIONS 1) KCl, intravenous, reduced the incidence of sertindole-induced TdP from 6 of 7 to 1 of 7 dogs (p<0.05) and prevented sertindole-related increase of STV: 3.0 +/- 1.1 ms vs. 4.5 +/- 1.3 ms (p < 0.05); 2) levcromakalim (I(K,ATP) activator) reduced sertindole-induced TdP and decreased STV from 4.9 +/- 2.1 ms to 2.6 +/- 0.9 ms (p < 0.05); 3) steady-state ventricular pacing (60 beats/min) abolished sertindole-induced TdP and decreased STV from 4.9 +/- 1.5 to 3.2 +/- 1.0 (p < 0.05). Torsades de pointes reappeared upon return to non-paced idioventricular rhythm. None of the 3 interventions reduced the sertindole-induced prolonged QT interval. CONCLUSIONS Proarrhythmic intervention is related to an increase in BVR, whereas antiarrhythmic treatment is associated with a decrease in BVR. The BVR is superior to QT interval prolongation in the prediction and prevention of drug-induced TdP in this experimental model.
Collapse
Affiliation(s)
- Morten B Thomsen
- Department of Medical Physiology, Heart Lung Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | | | | | | |
Collapse
|