Journal of pharmacological and toxicological methods最新文献

{"title":"Inferring ion channel block from rabbit Purkinje fiber action potential recordings","authors":"Luca Del Core ,&nbsp;Marcel Mohr ,&nbsp;Jean-Marie Chambard ,&nbsp;Véronique Ballet ,&nbsp;Ambroise Garry ,&nbsp;Friedemann Schmidt ,&nbsp;Gary R. Mirams","doi":"10.1016/j.vascn.2025.107816","DOIUrl":"10.1016/j.vascn.2025.107816","url":null,"abstract":"<div><div>Mathematical action potential (AP) models describe the changes in the membrane voltage due to a complex interplay between ionic currents, and their interactions with drug compounds. These models can guide preclinical risk assessments for drug-induced cardiac arrhythmia and extract more information from animal-based experiments. The rabbit Purkinje fiber has been used in preclinical studies, as it includes the major currents present in human ventricular myocytes. A recently proposed mathematical AP model of the rabbit Purkinje fiber, combined with ion channel screening data, predicted drug effects on AP changes, with an agreement of up to 80 % (Mohr et al., 2022). To explain the 20 % mismatch, we first improve the original AP model by re-calibrating its parameters to fit control AP traces. Subsequently we test our inference method in terms of uncertainty quantification of the control parameters. Finally, we compare the calibrated model and the original model in terms of prediction of AP %-changes induced by reference drug compounds with well-studied channel block properties and low measurement error (sd &lt; 10). Preliminary results indicate that after calibrating the ionic conductances, the correlation between observed and predicted %-change in APD50 (APD90) increased from −0.1 (0.04) to 0.43 (0.34). We are currently working on fitting model predictions to experimental AP changes in the presence of a new set of compounds, to infer the block of various ion channels, in terms of 50 % inhibitory concentration (IC50). The aim is to perform an experimental test for any computationally inferred IC50s which have not been measured, particularly for those drug compounds whose action potential changes are not explained by the existing ion channel screening data.</div></div>","PeriodicalId":16767,"journal":{"name":"Journal of pharmacological and toxicological methods","volume":"135 ","pages":"Article 107816"},"PeriodicalIF":1.8,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145094846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correlation electrical repolarization and membrane hERG abundance in iPSC cardiomyocytes induced by chronic drugs actions on channel trafficking","authors":"Niall MacQuaide ,&nbsp;Taylor Watters ,&nbsp;Shahrum G. Ghasemi ,&nbsp;Lewis Hamilton ,&nbsp;Mark Bryant ,&nbsp;Godfrey L. Smith","doi":"10.1016/j.vascn.2025.107818","DOIUrl":"10.1016/j.vascn.2025.107818","url":null,"abstract":"<div><div>The acute effects of drugs (~1 h) on the electrical activity, particularly those related to hERG block have been extensively studied in iPSC-derived cardiomyocytes (iPSC -CMs). However, long-term (&gt;12 h) drug exposure can also lead to slowly developing actions on hERG channels that result in QT prolongation, the most common are drugs that inhibit hERG trafficking to the surface membrane and cause an acquired long QT phenotype. The aim of the study is to assess the ability of iPSC-CM based assays to study the action of drugs known to inhibit hERG trafficking over a longer period using serum-free solutions. The following functional cellular parameters were measured over 72 h at 24 h intervals: (i) action potential duration (ii) contractile kinetics (iii) iPSC -CM monolayer integrity (iv) plasmalemma integrity (iv) membrane hERG expression. We used iCell2 (FujiFilm-CDI) iPSC -CMs, which we plated on a 96well plate and incubated in a serum free media. We performed automated image and signal analysis using a proprietary analysis platform (CellOPTIQ®- Clyde Biosciences). We tested 6 concentrations of Pentamidine and Arsenic Trioxide (ATO) which are both known to affect hERG trafficking and assessed chronic toxicity, electrophysiological, metabolic dysfunction. Pentamidine showed obvious prolongation of APD90 in the clinical range (1-3 μM) after 72 h and after 24 h at higher concentration (3-10 μM). ATO induced APD prolongation at 1-3 μM but shortening at 10 μM indicating mixed ion channel trafficking or metabolic effects. Western blot analysis of the membrane fraction showed significant downregulation of hERG expression of cells exposed to 48 h of 1 μM pentamidine. This work demonstrates the utility of chronic studies of IPSC-CMs to study the medium-long term actions of drugs on the hERG activity. The associated biochemical assays can confirm the extent to which reduction of hERG expression in the plasmalemmal membrane is responsible for the action.</div></div>","PeriodicalId":16767,"journal":{"name":"Journal of pharmacological and toxicological methods","volume":"135 ","pages":"Article 107818"},"PeriodicalIF":1.8,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145094848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intravenous self-administration – Valid experimental designs to evaluate the abuse potential of psychedelics, entactogens and drugs with novel mechanisms","authors":"David J. Heal ,&nbsp;Jane Gosden ,&nbsp;Sharon L. Smith","doi":"10.1016/j.vascn.2025.107793","DOIUrl":"10.1016/j.vascn.2025.107793","url":null,"abstract":"<div><div>Intravenous self-administration (IVSA) evaluates whether a CNS drug-candidate produces rewarding effects that could cause psychological dependence in patients and lead to its diversion for abuse. The model was originally developed to investigate powerful reinforcers like opiates and stimulants. For that reason, IVSA is not well adapted to detect the abuse potential of a new generation of drugs with moderate/low abuse potential. Using experience gained from conducting IVSA experiments with many types of drugs of abuse and novel drug-candidates, we offer insights on obtaining translationally predictive results from IVSA experiments, and technical refinements to increase the sensitivity and granularity of the findings. All experiments were conducted in mildly food-restricted, male, Sprague-Dawley rats with implanted with intravenous catheters. Standard IVSA tests were conducted on low fixed ratio (FR) schedules (FR3 or FR5), not FR10 as recommended in CDER/FDA guidance (CDER/FDA, 2017). As a technical refinement, the relative reinforcing effect was assessed by break-point determination on a progressive ratio (PR) schedule of reinforcement. All break-points were determined across a range of reinforcing drug doses to ensure the maximum reinforcing effect was identified. Moderate reinforcers, MDMA (entactogen), butorphanol (κ-agonist/μ-partial agonist), and (−)pentazocine (κ-agonist/μ-antagonist) produced break-points between 25 and 33 lever-presses/infusion. Weak reinforcers, WIN55,212 (CB1/CB2 agonist), diazepam, midazolam and methohexital (all GABA-A receptor positive allosteric modulators [PAMs]) produced mean break-points of 17–22 lever-presses/infusion. In contrast, powerful reinforcers like the opioids, eg heroin, remifentanil, oxycodone, and stimulants, eg cocaine, methylphenidate, supported mean break-points ranging between 41 and 98 lever‑presses/infusion. The break-point for saline (non-reinforcing control) was 10.4 ± 0.8 lever-presses/infusion. The results were used to design and conduct successful IVSA evaluations on cannabidiol (CBD), ulotaront and samidorphan on a FR3 schedule, difelikefalin, dasotraline, centanafadine, and soticlestat on a FR5 schedule, and PR/break-point determinations on samidorphan and naloxone. CNS drug development is in an era where new entactogens, psychedelics and drugs with novel mechanisms are undergoing clinical evaluation. Refinements to IVSA testing that we advocate have proven value based on experiments with known substances of abuse and novel drug-candidates.</div></div>","PeriodicalId":16767,"journal":{"name":"Journal of pharmacological and toxicological methods","volume":"135 ","pages":"Article 107793"},"PeriodicalIF":1.8,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparisons of hERG data for 30 drugs generated by automated and manual patch clamp systems by the same laboratory","authors":"Jun Zhao,&nbsp;Wendy W. Wu","doi":"10.1016/j.vascn.2025.107813","DOIUrl":"10.1016/j.vascn.2025.107813","url":null,"abstract":"<div><div>hERG block is the most common mechanism of drug-induced QT_C prolongation and the rare but potentially fatal arrhythmia Torsade de Pointes. Accordingly, hERG results are used to support first-in-human studies (ICH S7B), and new pathways have been developed to use hERG data generated following best practices (ICH S7B Q&amp;A 2.1) to complement clinical QT_C studies and to inform labeling (ICH E14 Q&amp;As 5.1 and 6.1). High-throughput, automated patch clamp systems (APC) can efficiently evaluate hERG block for new drug candidates. However, elements in APC experimental design and conduct, such as the use of non-physiological fluoride and recording temperature, have raised concerns regarding their impact on hERG pharmacology. This study compared hERG block potencies for 30 drugs collected using an APC to the same laboratory's manual patch clamp (MPC) data generated following best practices. MPC data are presented in a companion abstract by Alvarez-Baron et al. Recordings were conducted using SyncroPatch384 at 36 °C and 21 °C using fluoride-based internal solution and the same voltage protocol as the MPC. There was no systematic difference in IC₅₀s between the 36 °C APC and 37 ± 2 °C MPC data. Twenty-seven drugs (90 %) had APC IC₅₀ values within a range closely matching the MPC data. Reducing nonspecific binding by adding BSA or saturating binding sites with repeated drug applications lowered these drugs' IC₅₀s, suggesting that the largest differences are attributed to more drug loss in the APC experiments. Comparisons of the 36 °C and 21 °C APC data showed no systematic effect of temperature. Data from APC and MPC at near physiological temperature align well. Ongoing experiments are testing whether hERG data variability, determined by repeatedly obtaining IC₅₀ for the same drug, is drug-specific. The IC₅₀s variability needs to be accounted for when using the hERG safety margin to identify the likelihood of clinical QT_C prolongation. Empirically determining this using MPC is not practical. The ability to determine hERG data variability for different drugs rapidly is an advantage of APC that could lead to clearer comparisons of hERG safety margins of the investigational product and reference products.</div></div>","PeriodicalId":16767,"journal":{"name":"Journal of pharmacological and toxicological methods","volume":"135 ","pages":"Article 107813"},"PeriodicalIF":1.8,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145094843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Home cage analysis in double deck rat cages for safety pharmacology: A validation study","authors":"David Waiz ,&nbsp;Rowland R. Sillito ,&nbsp;Douglas Armstrong ,&nbsp;Andrea Greiter-Wilke","doi":"10.1016/j.vascn.2025.107794","DOIUrl":"10.1016/j.vascn.2025.107794","url":null,"abstract":"<div><div>Home cage analysis (HCA) technologies offer significant 3Rs benefits by measuring individual rodent behavior and physiological parameters within group housed animals. In recent years HCA approaches have been adopted in Safety Pharmacology in single deck cages. Increasingly animal facilities (and rack/cage suppliers) are providing ‘enriched’ double deck cage options for rats. We explored the feasibility of adapting HCA technology to the more complex environment in double deck cage systems and performed a single dose validation study. We adapted a previously published RFID and IR camera-based HCA system to fit a rat double deck cage. Additional RFID detectors covered the mezzanine area. Amphetamine at 0, 1, 3 and 10 mg/kg (<em>n</em> = 6–8 / dose) was tested as an initial reference compound in male Wistar Han rats, dosed AM (3 h into the inactive/light phase) or PM (30 min prior to entering active/dark phase) and effects measured for 24 h after both dosing events. We were able to track each individual animal on the cage base as well as along the mezzanine level including the vertical transitions between the two spatial zones. We could also measure a range of other parameters including activity, body temperature, drinking, rearing, and social proximity. Amphetamine induced dose-dependent increases in general activity, rearing, and body temperature in line with previously reported effects. Specific to the double deck cage, we observed significant increases in transitions between floor levels: a &gt; 6-fold increase (10 mg/kg) after AM dose (next 6 h inactive/light phase), and &gt; 4-fold (10 mg/kg) and &gt; 2-fold (3 mg/kg) increases after PM dose (first 6 h active/dark phase). Results aligned well with data from a parallel IRWIN examination. We show that HCA methods can be adapted to handle more complex environments such as double deck cages for rats. The core parameters obtained reproduce previous published findings for amphetamine. The more complex environment allows us to capture richer behaviors including increased numbers of transitions between the upper and lower decks which all showed dose dependent responses most striking during the PM dosed animals.</div></div>","PeriodicalId":16767,"journal":{"name":"Journal of pharmacological and toxicological methods","volume":"135 ","pages":"Article 107794"},"PeriodicalIF":1.8,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physiologic corrections for ECG intervals beyond QT","authors":"Sarah N. Freeman,&nbsp;Michael J. Murray-Busher,&nbsp;Alexa M. Spencer,&nbsp;Kenneth R. Kearney","doi":"10.1016/j.vascn.2025.107785","DOIUrl":"10.1016/j.vascn.2025.107785","url":null,"abstract":"<div><div>Quantitative assessment of ECG intervals informs investigators of drug activation within the heart. A limitation to understanding a test article's influence on specific ion channels can be due to extreme alterations in physiologic parameters, namely heart rate (HR) and body temperature (BT). While it's well understood that ECG intervals exhibit an expected inverse relationship to HR, it may be difficult to determine if changes in ECG intervals are disproportionately shortened or prolonged at extreme HRs. As QT prolongation is a known biomarker for increased Torsadogenic potential, in alignment with ICHS7B, HR correction formulae are employed to correct for QT interval duration. However, no direct guidance directs the correction of alternate intervals. Due to this, investigators are left to correlative comparisons between magnitude of change in HR and magnitude of change in the PR interval. While greater risks are known to be associated with ventricular arrhythmias, disproportionate shortening or prolongation of the PR interval may represent AV node dissociation, which could lead to AV Nodal reentry and subsequent potential of more significant ventricular arrhythmias. Recent studies have also suggested increased risk of atrial arrhythmias, heart failure, and mortality in patients with PR prolongation. In addition to direct HR influence, associations between BT and QT duration have been characterized in the dog (Van der Linde, 2008), but have not been completely profiled in the non-human primate (NHP). To address these gaps in physiologic corrections, an investigation of historical data was performed to determine if corrections were possible. Internal review (~60 animals/species – Beagle Dogs, NHPs) was utilized to establish the relationships between PR vs RR and QT vs BT intervals. Through this investigation, a species-specific correction for BT was established for NHP and exhibited equitable concordance to an individual animal correction. Therefore, this correction was believed to be an adequate precursory correction formula to adopt during acquisition to monitor for QT/BT. Contrarily, population-based corrections for PR vs RR exhibited variance, and individual study-based corrections were found to be most applicable. It is believed that employment of these additional physiological corrections may better profile the associated risks of new chemical entities.</div></div>","PeriodicalId":16767,"journal":{"name":"Journal of pharmacological and toxicological methods","volume":"135 ","pages":"Article 107785"},"PeriodicalIF":1.8,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Off-target of a novel TYK2 inhibitor is associated with myocardial necrosis mediated by hemodynamic changes in rats","authors":"Rebecca Kohnken,&nbsp;Stacey Fossey,&nbsp;Wayne R. Buck,&nbsp;Jason Segreti,&nbsp;Jessica Treadway,&nbsp;Jonathon Green,&nbsp;Yevgeniya E. Koshman,&nbsp;Mark Zafiratos,&nbsp;Scott Mittelstadt,&nbsp;Eric Blomme,&nbsp;Charles Michael Foley","doi":"10.1016/j.vascn.2025.107834","DOIUrl":"10.1016/j.vascn.2025.107834","url":null,"abstract":"<div><div>After an observation of myocardial necrosis and inflammation in rats administered an experimental TYK2 inhibitor (ABBV-712), investigative studies were performed to identify the potential mechanism. Telemetry instrumented rats were administered ABBV-712 with or without atenolol to assess hemodynamic changes and cardiac pathology. In vitro studies included cytotoxicity evaluation in human induced pluripotent stem cell-derived cardiomyocytes and assessment of relaxation of an isolated rat aorta model. Off-target pharmacology was evaluated by binding and inhibition screening assays. Finally, TYK2 knockout (KO) mice were instrumented with telemetry to determine hemodynamic changes as compared to wildtype animals following administration of ABBV-712. In these studies in rats, ABBV-712 resulted in decreased mean arterial pressure and increased heart rate that was prevented by pre-dosing atenolol. ABBV-712-induced myocardial pathology was also prevented by atenolol, consistent with a mechanistic link between hemodynamic changes and cardiac injury. The myocardial necrosis observed was determined to be unrelated to direct cytotoxicity on cardiomyocytes as demonstrated in vitro. Further, a compound-related effect on vascular relaxation mediated by endothelial cells was found in the aortic ring model. Overall the toxicity was considered an off-target effect, as suggested by similar hemodynamic responses between TYK2 KO and wildtype mice administered ABBV-712, as well as by the lack of hemodynamic changes in the KO mouse at baseline. Inhibition of the off-targets that were identified in the screening effort were considered unlikely to be the cause of the hemodynamic changes based on canonical pharmacology. In this study, a novel TYK2 small molecule inhibitor resulted in decreased mean arterial pressure, increased heart rate, and secondary myocardial necrosis in rats. These cardiovascular effects were unrelated to TYK2 inhibition. This report is an example of a cross-functional mechanistic investigation into the pharmacologic cause of an observation of cardiovascular toxicity.</div></div>","PeriodicalId":16767,"journal":{"name":"Journal of pharmacological and toxicological methods","volume":"135 ","pages":"Article 107834"},"PeriodicalIF":1.8,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145094588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Automated patch-clamp for high throughput characterization of subtype-specific induced pluripotent stem cell derived cardiomyocytes","authors":"Sonja Stoelzle-Feix ,&nbsp;Fitzwilliam Seibertz ,&nbsp;Marcus Lluis Gerloff ,&nbsp;Markus Rapedius ,&nbsp;Aiste Liutkute ,&nbsp;Lukas Cyganek ,&nbsp;Claudia Haarmann ,&nbsp;Michael George ,&nbsp;Niels Voigt ,&nbsp;Niels Fertig","doi":"10.1016/j.vascn.2025.107824","DOIUrl":"10.1016/j.vascn.2025.107824","url":null,"abstract":"<div><div>Atrial fibrillation (AF) represents the most prevalent cardiac arrhythmia observed in clinical practice. The efficacy of therapeutic interventions for AF remains suboptimal, and the exploration of ion channel remodeling mechanisms in AF is restricted by both the lack of atrial specificity in standard cell lines and the low throughput of ‘gold standard’ methodologies. Significant progress in the development of high throughput automated patch-clamp (APC) systems could be extremely beneficial for accelerating electrical investigations into the mechanisms of atrial-specific disorders such as AF. Human induced pluripotent stem cells (iPSC) were derived from dermal fibroblasts of a healthy male donor. Factor-free cardiac differentiation into iPSC derived cardiomyocytes (iPSC-CM) was achieved via small molecule temporal modulation of wnt signaling. Atrial specificity was induced through Retinoic acid (1 μM) application between day 3 and 6 of cardiac cell differentiation as has been previously shown (Seibertz et al., 2023). We describe the application of a high throughput APC device (SyncroPatch 384) to characterize key ionic currents and action potentials (AP) in human atrial- and ventricular-specific iPSC-CM. Thin borosilicate glass 384-well planar chips (1xS-type NPC-384 T) were used for all experiments. Recordings were excluded if they showed a seal resistance of &lt;250 MΩ or a peak current of &lt;50 pA. All measurements were carried out at room temperature. Robust current-clamp measurements of cardiac action potential revealed subtype-specific characteristics with shorter action potentials recorded in atrial iPSC-CM. High throughput voltage-clamp measurements of sodium current (INa), L-type calcium current (ICa,L), the rapid component of the delayed rectifier (IKr), and basal inward rectifier potassium current (IK1) were able to be measured in both cell types. In addition, activation of the atrial-specific acetylcholine-activated inward rectifier potassium current (IK,ACh) was exclusively observed in atrial but not in ventricular iPSC-CM following application of the M-receptor agonist carbachol. The successful application of a high throughput APC-system for the recording and characterization of atrial and ventricular APs and ionic currents in highly scalable iPSC-CM models implies that APC represents a powerful tool for future studies of atrial-specific pathologies such as AF.</div></div>","PeriodicalId":16767,"journal":{"name":"Journal of pharmacological and toxicological methods","volume":"135 ","pages":"Article 107824"},"PeriodicalIF":1.8,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145094727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of the J-Tpeak and Tpeak-to-tend intervals of the ECG as proarrhythmia biomarkers in telemetered dogs","authors":"Bétat Anne-Marie ,&nbsp;Delaunois Annie ,&nbsp;Loiseau Mathilde ,&nbsp;Poizat Gwendoline ,&nbsp;Maurin Anne ,&nbsp;Drieu la Rochelle Christophe ,&nbsp;Martel Eric ,&nbsp;Valentin Jean-Pierre ,&nbsp;Delpy Eric","doi":"10.1016/j.vascn.2025.107772","DOIUrl":"10.1016/j.vascn.2025.107772","url":null,"abstract":"<div><div>Since their implementation, the ICH S7B and E14 guidelines have been successful in that no new approved drugs have been withdrawn from the market due to unanticipated risk of Torsade de Pointe (TdP). While hERG block and QTc prolongation biomarkers are indeed sensitive, they are not specific as multiple drugs block hERG and/or prolong QTc but do not cause TdP. The J-Tpeak interval (JTp) of the ECG has recently been proposed as a novel clinical biomarker to differentiate selective hERG blockers from multi cardiac ion channels inhibitors. Therefore, the present study aimed at evaluating the effects of dofetilide (pure hERG blocker) and dolasetron (balanced ion-channel blocking drug) on QT, JTp and Tpeak-to-Tend (TpTe) Intervals in telemetered conscious dogs, in comparison with levocetirizine, used as a QT negative control drug. The experiments were carried out using 7 dogs previously instrumented with a telemetry implant. Using a cross-over design, each drug was administered at two doses (0.03/0.15, 6/20, 2/10 mg/kg p.o. for dofetilide, dolasetron and levocetirizine, respectively) and ECG monitored over 24 h post-dosing. Dedicated PK sessions were performed to measure corresponding plasma exposure. QT, JTp and TpTe intervals were individually corrected (c) for heart rate variations. Total plasma drug concentrations increased dose-proportionally. Compared to vehicle, dofetilide induced dose-dependent, marked, and long-lasting increases in both QTc and JTpc intervals, confirming predominant hERG blockage by dofetilide. However, no effect was observed on TpTec interval. In contrast, QTc prolongation associated with dolasetron was moderate and transient and no effect on JTpc was observed; interestingly, dolasetron slightly increased TpTec and QRS intervals, as well as PR interval, reflecting its inhibitory effect on calcium and sodium currents. As expected, levocetirizine had no effect, at any dose or timepoint post-dosing. To summarize, pure hERG-blocking drug (such as dofetilide) prolonged both QTc and JTpc, whereas drug with mixed ion channel blockage (such as dolasetron) prolonged QTc but not JTpc. In conclusion, evaluating the effects of a drug on the J-Tpeak interval may be relevant in cardiovascular safety pharmacology studies to complement the QT interval as a sensitive and more specific biomarker for proarrhythmic risk.</div></div>","PeriodicalId":16767,"journal":{"name":"Journal of pharmacological and toxicological methods","volume":"135 ","pages":"Article 107772"},"PeriodicalIF":1.8,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The translation of hERG block and APD90 in vitro to clinical QTc prolongation in man","authors":"Derek J. Leishman ,&nbsp;Najah Abi-Gerges","doi":"10.1016/j.vascn.2025.107804","DOIUrl":"10.1016/j.vascn.2025.107804","url":null,"abstract":"<div><div>The core ICH S7B in vitro assay is a hERG assessment which has associated best practice recommendations. Three reference agents are being used to compare margins based on concentrations associated with 10 ms QTc prolongation in man. The objective of the current analyses was to compare the margins for best practice hERG patch-clamp data with those for other in vitro assessments. The unbound critical concentrations shared as part of the Training Materials were used as the denominator throughout. The numerators were: the hERG IC₅₀ generated in a study conforming to current best practice guidance, the pKi from published dofetilide-binding data, the concentrations associated with either published rate corrected APD₉₀ prolongation in isolated IPD-derived human cardiomyocytes, or with a 25 ms change in APD₉₀ in human ventricular trabeculae tissue. The respective margins for dofetilide, moxifloxacin and ondansetron in the patch-clamp study were 45, 32 and 4.2. The dofetilide-binding displacement pKi, gave margins of 11, 15 and 10. In isolated cardiomyocytes the margins were 0.5, 5.2 and 1.3. In human trabeculae tissue the margins were 14, 4.5 and 9. There is an underlying assumption that for selective hERG blocking drugs the amount of hERG block (and associated hERG margin) would be similar for the same 10 ms change in QTc. The consistent margin determined using the dofetilide-binding displacement pKi and the concentration associated with a 25 ms APD90 prolongation in human trabeculae would tend to support that assessment. There was more variability in isolated cardiomyocytes where there was an 11-fold difference between dofetilide and moxifloxacin margins while the ondansetron margin lay in between these margins. The hERG patch-clamp study had skewed variability with a margin for ondansetron 11-fold and 8-fold different from the margins for dofetilide and moxifloxacin, respectively. The small margin for ondansetron caused wider confidence intervals for the pooled margin of 18-fold. Overall, these data suggest that any of these assays might realistically be used to predict a QTc prolongation in man. The hERG patch-clamp study is the required study. Where there are ‘ondansetron-like’ blocking characteristics an additional assay may be warranted to clarify the prediction.</div></div>","PeriodicalId":16767,"journal":{"name":"Journal of pharmacological and toxicological methods","volume":"135 ","pages":"Article 107804"},"PeriodicalIF":1.8,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145094931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}