Effects of Bepridil and Pimozide, Existing Medicines Capable of Blocking T-Type Ca2+ Channels, on Visceral Pain in Mice.

T-Type Ca2+ channels (T-channels), particularly Cav3.2, are now considered as therapeutic targets for treatment of intractable pain including visceral pain. Among existing medicines, bepridil, a multi-channel blocker, used for treatment of arrhythmia and angina, and pimozide, a dopamine D2 receptor antagonist, known as a typical antipsychotic, have potent T-channel blocking activity. We thus tested whether bepridil and pimozide could suppress visceral pain in mice. Colonic and bladder pain were induced by intracolonic administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) and systemic administration of cyclophosphamide (CPA), respectively. Referred hyperalgesia was assessed by von Frey test, and colonic hypersensitivity to distension by a volume load with intracolonic water injection and spontaneous bladder pain were evaluated by observing nociceptive behaviors in conscious mice. The mice exhibited referred hyperalgesia and colonic hypersensitivity to distension on day 6 after TNBS treatment. Systemic administration of bepridil at 10-20 mg/kg or pimozide at 0.1-0.5 mg/kg strongly reduced the referred hyperalgesia on the TNBS-induced referred hyperalgesia and colonic hypersensitivity to distension. CPA treatment caused bladder pain-like nociceptive behavior and referred hyperalgesia, which were reversed by bepridil at 10-20 mg/kg or pimozide at 0.5-1 mg/kg. Our data thus suggest that bepridil and pimozide, existing medicines capable of blocking T-channels, are useful for treatment of colonic and bladder pain, and serve as seeds for the development of new medicines for visceral pain treatment.

Bepridil Inhibits Premature Ventricular Complexes Induced by Cardio-Sympathetic Nerve Stimulation in a Canine Experimental Model.

Sympathetic nerve activity has arrhythmogenic potential for ventricular arrhythmias associated with structural heart diseases. However, a sufficient amount of beta-blockers occasionally cannot be prescribed in some patients.An experimental study was performed to clarify the therapeutic effects of bepridil, a multiple ionic current inhibitor that does not affect beta-adrenergic receptors, for premature beats occurring during enhanced sympathetic nerve activity. Cardio-sympathetic nerve activity was augmented via stellate-ganglion (SG) stimulation in a canine model (n = 8), and the arrhythmogenic potential and anti-arrhythmic effects of bepridil (2 and 4 mg/kg intravenously) were assessed. For safe use, vagal-stimulation-induced slow HR and programmed electrical stimulation were applied to evaluate possible pro-arrhythmic effects of the drug. Heart rate variability (HRV) indexes were used to estimate cardio-autonomic nerve activity.Either side of the SG-stimulation increased BP and HR. Premature beats were induced in 10/16 SG-stimulations and it was more frequent in left (8/8) rather than right stimulation (2/8). Following 2 mg/kg drug administration, premature beats were still inducible in 8/16 stimulations (7/8 in left and 1/8 in right), but burden of the premature beats decreased from 87.1 ± 46.8 to 62.1 ± 42.6 beats. After 4 mg/kg administration, premature beats were inducible in one SG-stimulation. Proarrhythmic effects were not observed in all experiments. Steady-state HRV indexes and percent increases in SG-stimulation-induced BP-elevation and HR-acceleration were similar among the 3 periods (before, 2 and 4 mg/kg of the drug).Bepridil may be an option for ventricular arrhythmias developed during enhanced cardio-sympathetic nerve activity with minimal effect on autonomic nerve responses.

Blockade of the forward Na+ /Ca2+ exchanger suppresses the growth of glioblastoma cells through Ca2+ -mediated cell death.

BACKGROUND AND PURPOSE: The Na+ /Ca2+ exchanger (NCX) working in either forward or reverse mode participates in maintaining intracellular Ca2+ ([Ca2+ ]i ) homeostasis, which is essential for determining cell fate. Previously, numerous blockers targeting reverse or forward NCX have been developed and studied in ischaemic tissue injury but barely examined in glioblastoma for the purpose of anti-tumour therapy. We assessed the effect of NCX blockers on glioblastoma growth and whether NCX can become a therapeutic target. EXPERIMENTAL APPROACH: Patch-clamp recording, Ca2+ imaging, flow cytometry, and Western blot were used to study the effects of specific and non-specific NCX blockers on cultured glioblastoma cells. In vivo bioluminescent imaging was used to measure effects on grafted glioblastoma. KEY RESULTS: Selectively blocking the reverse NCX with SEA0400, SN-6, and YM-244769 did not affect tumour cell viability. Blocking the forward NCX with bepridil, CB-DMB, or KB-R7943 elevated [Ca2+ ]i and killed glioblastoma cells. Bepridil and CB-DMB caused Ca2+ -dependent cell cycle arrest together with apoptosis, which were all attenuated by a Ca2+ chelator BAPTA-AM. Systemic administration of bepridil inhibited growth of brain-grafted glioblastoma. Bepridil did not appear to have a cytotoxic effect on human astrocytes, which have higher functional expression of NCX than glioblastoma cells. CONCLUSIONS AND IMPLICATIONS: Low expression of the NCX makes glioblastoma cells sensitive to disturbance of [Ca2+ ]i . Interventions designed to block the forward NCX can cause Ca2+ -mediated injury to glioblastoma thus having therapeutic potential. Bepridil could be a lead compound for developing new anti-tumour drugs.

Novel drug candidate for the treatment of several soft­tissue sarcoma histologic subtypes: A computational method using survival­associated gene signatures for drug repurposing.

Systemic treatment options for soft tissue sarcomas (STSs) have remained unchanged despite the need for novel drug candidates to improve STS outcomes. Drug repurposing involves the application of clinical drugs to different diseases, reducing development time, and cost. It has also become a fast and effective way to identify drug candidates. The present study used a computational method to screen three drug­gene interaction databases for novel drug candidates for the treatment of several common STS histologic subtypes through drug repurposing. STS survival­associated genes were generated by conducting a univariate cox regression analysis using The Cancer Genome Atlas survival data. These genes were then applied to three databases (the Connectivity Map, the Drug Gene Interaction Database and the L1000 Fireworks Display) to identify drug candidates for STS treatment. Additionally, pathway analysis and molecular docking were conducted to evaluate the molecular mechanisms of the candidate drug. Bepridil was identified as a potential candidate for several STS histologic subtype treatments by overlapping the screening results from three drug­gene interaction databases. The pathway analysis with the Kyoto Encyclopedia of Genes and Genomes predicted that Bepridil may target CRK, fibroblast growth factor receptor 4 (FGFR4), laminin subunit ß1 (LAMB1), phosphoinositide­3­kinase regulatory subunit 2 (PIK3R2), WNT5A, cluster of differentiation 47 (CD47), elastase, neutrophil expressed (ELANE), 15­hydroxyprostaglandin dehydrogenase (HPGD) and protein kinase cß (PRKCB) to suppress STS development. Further molecular docking simulation suggested a relatively stable binding selectivity between Bepridil and eight proteins (CRK, FGFR4, LAMB1, PIK3R2, CD47, ELANE, HPGD, and PRKCB). In conclusion, a computational method was used to identify Bepridil as a potential candidate for the treatment of several common STS histologic subtypes. Experimental validation of these in silico results is necessary before clinical translation can occur.

The Calcium Channel Blocker Bepridil Demonstrates Efficacy in the Murine Model of Marburg Virus Disease.

No therapeutics are approved for the treatment of filovirus infections. Bepridil, a calcium channel blocker developed for treating angina, was identified as a potent inhibitor of filoviruses in vitro, including Ebola and Marburg viruses, and Ebola virus in vivo. We evaluated the efficacy of bepridil in a lethal mouse model of Marburg virus disease. A dose of 12 mg/kg bepridil once or twice daily resulted in 80% or 90% survival, respectively. These data confirm bepridil's broad-spectrum anti-filovirus activity warranting further investigation of bepridil, or improved compounds with a similar mechanism, as a pan-filovirus therapeutic agent.

Effects of bepridil on stretch-activated BKca channels and stretch-induced extrasystoles in isolated chick hearts.

Various types of mechanosensitive ion channels, including cationic stretch-activated channels (SAC(NS)) and stretch-activated BKca (SAKca) channels, modulate heart rhythm. Bepridil has been used as an antiarrhythmic drug with multiple pharmacological effects; however, whether it is effective for mechanically induced arrhythmia has not been well investigated. To test the effects of Bepridil on SAKca channels activity, cultured chick embryonic ventricular myocytes were used for single-channel recordings. Bepridil significantly reduced the open probability of the SAKca channel (P(O)). Next, to test the effects of bepridil on stretch-induced extrasystoles (SIE), we used an isolated 2-week-old Langendorff-perfused chick heart. The left ventricle (LV) volume was rapidly changed, and the probability of SIE was calculated in the presence and absence of bepridil, and the effect of the drug was compared with that of Gadolinium (Gd(3+)). Bepridil decreased the probability of SIE despite its suppressive effects on SAKca channel activity. The effects of Gd(3+), which blocks both SAKca and SAC(NS), on the probability of SIE were the same as those of bepridil. Our results suggest that bepridil blocks not only SAKca channels but possible also blocks SAC(NS), and thus decreases the stretch-induced cation influx (stabilizing membrane potential) to compensate and override the effects of the decrease in outward SAKca current (destabilizing membrane potential).

Impact of postprocedural antiarrhythmic drug therapy with bepridil on maintaining sinus rhythm after catheter ablation for persistent atrial fibrillation.

BACKGROUND: Although several studies have assessed the predictors of recurrent atrial fibrillation (AF) after catheter ablation for persistent AF, the impact of antiarrhythmic drug (AAD) therapy on maintaining sinus rhythm after catheter ablation for persistent AF has not been fully evaluated. This case-control study aimed to evaluate the effect of bepridil on maintaining sinus rhythm after catheter ablation for persistent AF. METHODS AND RESULTS: We enrolled 122 consecutive patients (87 men; mean age: 62.3 years) who underwent catheter ablation for persistent AF and were administered AAD therapy after the initial procedure. Restoration of sinus rhythm was achieved in all of the patients by catheter ablation and cardioversion after the initial procedure. After a median 12-month follow up, 51 of 122 (41.8%) patients had recurrence of AF. In Cox proportional hazard regression analysis, postprocedural AAD therapy with bepridil was a significantly correlated factor with freedom from recurrent AF after the initial ablation procedure (hazard ratio 0.446, 95% confidence interval 0.236-0.842, p=0.012). In Kaplan-Meier analysis, AF-free survival was significantly better with bepridil compared with amiodarone (AMD) and sodium channel blocker (SCB) (log-rank test, bepridil vs AMD, p=0.012; bepridil vs SCB, p=0.018). CONCLUSIONS: Bepridil reduced the recurrence of AF compared with AMD and SCB in patients who underwent catheter ablation for persistent AF.

Non-selective calcium channel blocker bepridil decreases secondary pathology in mice after photothrombotic cortical lesion.

Experimental studies have identified a complex link between neurodegeneration, ß-amyloid (Aß) and calcium homeostasis. Here we asked whether early phase ß-amyloid pathology in transgenic hAPPSL mice exaggerates the ischemic lesion and remote secondary pathology in the thalamus, and whether a non-selective calcium channel blocker reduces these pathologies. Transgenic hAPPSL (n = 33) and non-transgenic (n = 30) male mice (4-5 months) were subjected to unilateral cortical photothrombosis and treated with the non-selective calcium channel blocker bepridil (50 mg/kg, p.o., once a day) or vehicle for 28 days, starting administration 2 days after the operation. Animals were then perfused for histological analysis of infarct size, Aß and calcium accumulation in the thalamus. Cortical photothrombosis resulted in a small infarct, which was associated with atypical Aß and calcium accumulation in the ipsilateral thalamus. Transgenic mice had significantly smaller infarct volumes than non-transgenic littermates (P<0.05) and ischemia-induced rodent Aß accumulation in the thalamus was lower in transgenic mice compared to non-transgenic mice (P<0.01). Bepridil decreased calcium load in the thalamus (P<0.01). The present data suggest less pronounced primary and secondary pathology in hAPPSL transgenic mice after ischemic cortical injury. Bepridil particularly decreased calcium pathology in the thalamus following ischemia.

Carvedilol is effective and safe in combination with bepridil for persistent atrial fibrillation and decreases the QT prolongation induced by bepridil therapy.

INTRODUCTION: We investigated the efficacy of carvedilol for preventing the recurrence of atrial fibrillation and reducing QT prolongation induced by bepridil. METHODS: We assigned 144 subjects with persistent atrial fibrillation. The subjects were divided into 3 groups: carvedilol plus bepridil, candesartan plus bepridil, and bepridil alone. The primary endpoint was length of time to the recurrence of atrial fibrillation. All subjects were followed up for 3 years. Electrocardiographic parameters were measured for QT interval, QTc, heart rate, and QRS duration. RESULTS: The pharmacological conversion rate by carvedilol plus bepridil was 77%, candesartan plus bepridil was 63%, and bepridil alone was 57%. The significant difference was between carvedilol plus bepridil and bepridil alone (P = 0.03). The maintenance of SR at 3 years was 60% in carvedilol plus bepridil, 59% in candesartan plus bepridil, and 40% in bepridil alone. The difference between carvedilol plus bepridil and bepridil alone was statistically significant (P = 0.04). QTc and QT interval were significantly prolonged in candesartan plus bepridil and bepridil alone but not in carvedilol plus bepridil. CONCLUSIONS: The authors demonstrated that the combination therapy with carvedilol plus bepridil is more effective for maintaining SR than bepridil alone therapy and carvedilol reduced QT prolongation by bepridil therapy.

Bepridil is effective and improves QOL in multidrug-resistant paroxysmal atrial fibrillation.

OBJECTIVE: Efficacy and safety of long-term administration of bepridil as a rhythm and rate controller were comprehensively evaluated in patients with multidrug-resistant paroxysmal atrial fibrillation (PAF). METHODS: A retrospective survey from 1992 to 2006 was conducted on 62 multidrug-resistant PAF patients treated with bepridil from 480 consecutive PAF patients. In addition, a 5-year follow-up study was conducted on 28 of the 62 patients, being continued from 2006 to 2011. The efficacy of bepridil, improvement in symptoms including patients' quality of life (QOL), ECGs, hemodynamics, and its adverse effects were examined. RESULTS: In the retrospective survey, 127 ±â€Š44 mg of bepridil was given for 21 ±â€Š18 months and 40.3% maintained sinus rhythm. Reductions in the frequency and the duration of each episode of PAF and improvement in symptoms were seen in 48.4, 50.0 and 93.5% of the 62 patients, respectively. Reversible torsades de pointes (TdP) occurred in two aged women. Bradycardia and hepatic dysfunction developed in one patient each. In the follow-up study, 100 ±â€Š20 mg of bepridil was given. Sinus rhythm was maintained in 13 patients. Although the occurrences of PAF continued in 14 patients, their symptoms and QOL were improved. No adverse effects were noted in all 28 patients of the follow-up study. CONCLUSIONS: Bepridil was effective in rhythm control in 40% of PAF patients resistant to other antiarrhythmics. Even in those who had failed to maintain sinus rhythm, continued administration of low-dose bepridil improved their symptoms and QOL with few adverse effects. Bepridil is worth returning to use.

The relationship between the plasma concentration of bepridil and its efficacy in the treatment of atrial fibrillation in Japanese patients.

Bepridil hydrochloride is used for treatment of atrial fibrillation (AF) in Japan. We investigated the relationship between plasma concentrations of bepridil just before dosing (Cbep) and its clinical efficacy in Japanese patients (n=36) with AF. Patients were treated orally with 100, 150 or 200 mg/d bepridil. Cbep were measured with UV-HPLC. In the first 14 d, when 150, 200, 250 or 300 ng/mL was set as a boundary value, the efficacy of bepridil was significantly higher in all patients with Cbep above than below the boundary value (p<0.05). In the maintenance stage (3 months longer after starting therapy), the efficacy of bepridil was significantly higher in patients with Cbep above than below 300 ng/mL (p=0.04). The clinical efficacy of bepridil was closely related to Cbep. The target value of Cbep to obtain a clinical benefit was approximately 300 ng/mL. Monitoring Cbep should be useful in the treatment of patients with AF.

Clinical outcome in patients with paroxysmal or persistent atrial fibrillation receiving bepridil.

BACKGROUND: It is unknown whether bepridil improves cardiovascular events in atrial fibrillation (AF) patients, so this study evaluated the clinical outcome in paroxysmal or persistent AF patients receiving bepridil. METHODS AND RESULTS: We conducted a cohort study of 284 consecutive patients who received bepridil for AF (25% female, 5913 years) with a median follow-up period of 17 months (4-157 months). A total of 135 (48%) patients had structural heart disease, and 231 patients (81%) had previously received class I or class III antiarrhythmic drugs. The cumulative rates for cardiovascular events were 2.4%, 8.1%, and 10.1% at 1, 3, and 5 years, respectively. The cumulative rates for a composite of mortality, cerebral infarction, systemic embolism, major bleeding and heart failure were 9.7%, 18.2%, and 29.6% at 1, 3, and 5 years, respectively. The probability of progression to permanent AF was 23.5% at 5 years. Sudden death occurred in a patient with a prior myocardial infarction who was taking 200mg daily, and torsade de pointes (Tdp) occurred in two patients without structural heart disease taking 200mg daily. Excessive corrected QT interval prolongation (>0.50s) was observed when plasma concentrations were higher than 800 ng/ml. CONCLUSIONS: Bepridil might not improve the clinical outcome in refractory AF patients. Bepridil-related adverse events, including QT prolongation and Tdp, occurred in a dose- and concentration-dependent manner.

In vitro and experimental therapeutic studies of the calcium channel blocker bepridil: detection of viable Leishmania (L.) chagasi by real-time PCR.

The need for novel and efficacious drugs against neglected parasitic diseases, such as Leishmaniasis and American Trypanosomiasis, is certainly apparent. In this work, we evaluated the in vitro potential of the calcium channel blocker bepridil against Leishmania spp. and Trypanosoma cruzi parasites and exploited an experimental assay using a hamster model with Leishmania (L.) chagasi, with a real-time PCR method for therapeutic evaluation. Bepridil was in vitro effective against promastigotes and intracellular amastigotes of L. (L.) chagasi, with 50% inhibitory concentration (IC(50)) values of 3.81 and 21.55 µM, respectively. Leishmania (L.) amazonensis, L. (L.) major and L. (V.) braziliensis promastigotes and T. cruzi trypomastigotes were also susceptible to bepridil, with in vitro selectivity toward parasites and IC(50) values in the range of 3 to 7 µM. The mammalian cytotoxicity using LLC-MK2 cells resulted in an IC(50) value of 62.67 µM. However, bepridil showed lack of activity at 12 mg/kg in the experimental hamster model infected with L. (L.) chagasi parasites. However, the real-time PCR was a promising tool for the accurate and fast quantification of RNA of living parasites in the liver and spleen of infected hamsters after treatment, eliminating time-consuming light microscopy evaluations.

Bepridil facilitates early termination of spiral-wave reentry in two-dimensional cardiac muscle through an increase of intercellular electrical coupling.

Bepridil is effective for conversion of atrial fibrillation to sinus rhythm and in the treatment of drug-refractory ventricular tachyarrhythmias. We investigated the effects of bepridil on electrophysiological properties and spiral-wave (SW) reentry in a 2-dimensional ventricular muscle layer of isolated rabbit hearts by optical mapping. Ventricular tachycardia (VT) induced in the presence of bepridil (1 µM) terminated earlier than in the control. Bepridil increased action potential duration (APD) by 5% - 8% under constant pacing and significantly increased the space constant. There was a linear relationship between the wavefront curvature (κ) and local conduction velocity: LCV = LCV0 - D·κ (D, diffusion coefficient; LCV0, LCV at κ = 0). Bepridil significantly increased D and LCV0. The regression lines with and without bepridil crossed at κ = 20 - 40 cm⁻¹, resulting in a paradoxical decrease of LCV at κ > 40 cm⁻¹. Dye transfer assay in cultured rat cardiomyocytes confirmed that bepridil increased intercellular coupling. SW reentry in the presence of bepridil was characterized by decremental conduction near the rotation center, prominent drift, and self-termination by collision with boundaries. These results indicate that bepridil causes an increase of intercellular coupling and a moderate APD prolongation, and this combination compromises wavefront propagation near the rotation center of SW reentry, leading to its drift and early termination.

Efficacy of low-dose bepridil for prevention of ventricular fibrillation in patients with Brugada syndrome with and without SCN5A mutation.

It has been reported that bepridil prevents ventricular fibrillation (VF) in patients with Brugada syndrome, but the comparative efficacy with and without mutation in the SCN5A gene has not been elucidated. The purpose of this study was to assess the efficacy of low-dose bepridil (100 mg/day) for VF prevention in patients with Brugada syndrome with and without SCN5A mutation. Among 130 patients with Brugada-type electrocardiogram (ECG), low-dose bepridil was administered to seven patients because of repetitive VF episodes, including three with and four without SCN5A mutation. Preventive effect for VF recurrence and changes of the ECG and the signal-averaged ECG were evaluated. Frequencies of VF episodes were reduced after treatment with low-dose bepridil in all three patients with the SCN5A mutation (before: 0.33 versus after: 0.02 episodes/month, P < 0.01), but not in all four patients without the SCN5A mutation (before: 0.43 versus after: 2.94 episodes/month, P = nonsignificant). Levels of ST-segment elevation at J points and duration of low-amplitude signals less than 40 µV in the terminal filtered QRS complex (LAS40) in signal-averaged ECG were improved exclusively in patients with the SCN5A mutation. Treatment with bepridil prevented recurrence of VF along with improvement of ST elevation and LAS40 in patients with Brugada syndrome with the SCN5A mutation.

Candesartan decreases type III procollagen-N-peptide levels and inflammatory marker levels and maintains sinus rhythm in patients with atrial fibrillation.

This study has evaluated whether candesartans prevent the recurrence of atrial fibrillation (AF) and decrease type III procollagen-N-peptide (PIIINP) levels. A total of 153 patients with AF were enrolled in this study. Three groups of patients were compared; candesartan group was treated with candesartan plus bepridil (n = 52); and carvedilol group with carvedilol plus bepridil (n = 51); and bepridil group with bepridil alone (n = 50). The primary end point was length of time to the recurrence of AF and all patients were ultimately followed-up for 730 days. Serum levels of the biomarkers were measured at baseline and after 24 months. Maintenance of sinus rhythm was achieved in 25 (50%) patients in bepridil group, 37 (73%) in candesartan group, and 34 (67%) in carvedilol group, giving a bepridil group/candesartan group hazard ratio of 0.36 (95% confidence interval 0.21-0.63; P = 0.03). Candesartan significantly decreased PIIINP levels at 24 months than at baseline in sinus rhythm group (0.57 +/- 0.02 vs. 0.64 +/- 0.05 U/mL, P = 0.04) and did not decrease PIIINP levels in the recurrence group. In conclusions, PIIINP might be related to the possibility of the atrial fibrosis for AF. However, further studies are needed to clarify the relationship between PIIINP and AF.

Opposing effects of bepridil on ventricular repolarization in humans. Inhomogeneous prolongation of the action potential duration vs flattening of its restitution kinetics.

BACKGROUND: Bepridil is highly effective in the treatment of atrial fibrillation, but its clinical usefulness is limited by a potential risk for the drug-induced Torsades de pointes (TdP) in association with its Class III action. METHODS AND RESULTS: Monophasic action potentials (MAPs) were recorded from the right ventricular outflow tract (RVOT) and apex (RVA) in 9 patients treated with bepridil (172 +/-26 mg/day) and 10 control patients. Bepridil significantly increased the steady-state MAP durations at 90% repolarization (MAPD(90S) in a rate-independent manner at pacing cycle lengths ranging from 330 to 750 ms. The bepridil-induced prolongation of the MAPD(90) was greater in RVOT (approximately 13%) than RVA (approximately 8%). Bepridil flattened the MAPD(90) restitution slope estimated by an S1-S2 protocol in both the RVOT (0.65 +/-0.22 vs 0.95 +/-0.38) and RVA (0.65 +/-0.14 vs 0.94 +/-0.29). The T(peak-end) interval in the ECG was increased by bepridil for S1 but not S2 at the shortest diastolic interval to produce a ventricular response. CONCLUSIONS: Bepridil produces an inhomogeneous prolongation of the MAPDs, but flattens their restitution kinetics in the human ventricle. The former effect would favor the functional reentry predisposing to TdP, whereas the latter one would counteract that by reducing the dynamic instability of the repolarization.